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Dr Oz Loses More Respect! Part 1 – Green Coffee Bean Extract

Posted on May 6th, 2012 by Jeff Thiboutot M.S.

I happened to watch a recent episode of Dr Oz, something I don’t typically do. But, when I was flipping through the channels I saw that Dr Oz was going to be talking about some new breakthrough weight loss supplement which obviously got my attention. He was also going to discuss natural ways to relieve bloating. Both topics sounded interesting and I had a bit of free time, so I decided to watch it.

First, HERE is the segment about the supplement,which is green coffee bean extract (GCE). Did you watch it? This will all make more sense if you do. It is clear that Dr Oz agrees that this supplement is amazing. He states that he was skeptical. So what did he do to help confirm the benefits of the supplement? Did he actually read the available research on the subject? From what he agreed to and what he said on the show we can assume he did NOT. Instead he gives the supplement to 2 viewers so they could take it for 5 days to see if they would lose weight. Really!? WTF! Is he serious about this type of testing? Apparently he is. The two viewers did lose weight, 2 and 6 lbs. That’s great, but come on. That really does not tell us if the “supplement” actually did something on a physiological level or if it just made them modify their eating behavior so that they would lose weight. Basically, having the 2 viewers take the supplement for 5 days is a big waste of time! Dr. Oz should know better.

The guest on the show, Dr.Lindsey Duncan,  says a bunch of, how should I say this, ah… BULLSHIT! That sums it up well. Here are some statements by Dr.Duncan; (some paraphrased)

  • “each participant lost 17lbs in 12 weeks”
  • “lost 10% of body weight with no change in eating or activity”
  • “sugar turns into fat”
  • “makes the body burn fat in the liver”
  • “take 800 mg 2 times a day”
  • “roasting coffee beans removes the chlorogenic acid, so coffee does not contain this compound”

These are apparently the important aspects about what the supplement does, how it works and how much to take. Really! Well, I guess it is time to look at this study as it seems to be the impetus for all the hubbub.

The paper is freely available, click HERE if you would like to read it, attention Dr Oz, I am referring to you as well.

Vinson, J et al (2012). Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects. Diabetes Metab Syndr Obes; 5: 21–27.

Overall, I think this was a decent study. However, there are two very important limitations to it. First, there where only 16 total participants. Second, the dietary intake was NOT tightly regulated. Dietary intake was assessed through dietary recall, however the specifics of this aspect are not clearly stated in the paper. This is very important because dietary recall is well know to be a rather poor method of assessing true food/calorie intake. A nice 8 to 12 week, metabolic ward study with a few dozen, overweight and obese, male and female participants would go a long way in determining the true physiological benefit of this supplement. Until then we have to go with what we have.

There where 3 groups (treatment arms)

  • HD (high dose): 350 mg of GCA (green coffee extract) taken 3 x day, total of 1,050 mg/day
  • LD (low dose): 350 mg of GCA taken 2 x day, total of 700 mg/day
  • PL (placebo): 350 mg of a placebo taken 3 x day

Each arm was followed for 6 weeks.

Results (p.24) at the end of each arm (6 weeks each)

  • HD: average decrease of 4.48lbs, lose of x .75 lbs per week
  • LD: average decrease of 3.39lbs, lose of x .57 lbs per week
  • PL: no real change

Combining the HD and the LD arms resulted in a grand total of 7.87lbs lost during 12 weeks, which is a bit less than 5% of bodyweight. This averages to a decrease of .66 lbs per week. Not bad. In fact, I would say the results were pretty damn good for just taking a relatively safe supplement.

Table 2 [pg 24]
Characteristics at start and end of each treatment arm for 16 preobese subjects
Characteristic HD arm P LD arm P PL arm P

M ± SD (95% CI)
M ± SD (95% CI)
M ± SD (95% CI)
M ± SD (95% CI)
M ± SD (95% CI)
M ± SD (95% CI)
Weight (kg) 72.86 ± 8.91 (68.11–77.61) 70.82 ± 8.40 (66.34–75.30) 0.002 71.25 ± 7.30 (67.36–75.14) 69.71 ± 7.30 (65.82–73.60) 0.003 72.15 ± 8.64 (67.55–76.75) 72.47 ± 8.47 (67.96–76.98) 0.353
BMI (kg/m2) 26.78 ± 1.55 (25.95–27.61) 26.03 ± 1.36 (25.31–26.75) 0.002 26.25 ± 1.37 (25.52–26.98) 25.66 ± 1.20 (25.02–26.30) 0.003 26.55 ± 1.96 (25.51–27.59) 26.67 ± 1.72 (25.75–27.59) 0.384
Percent body fat 25.94 ± 5.35 (23.09–28.79) 24.75 ± 5.20 (21.98–27.52) 0.001 25.94 ± 4.99 (23.28–28.60) 24.88 ± 4.99 (22.22–27.54) 0.002 25.88 ± 5.40 (23.00–28.76) 25.00 ± 5.52 (22.20–27.82) 0.014
HR (bpm) 76.94 ± 2.64 (75.53–78.35) 75.12 ± 3.63 (73.19–77.05) 0.031 74.62 ± 4.56 (72.19–77.05) 74.87 ± 4.50 (72.47–77.27) 0.752 76.19 ± 5.13 (73.46–78.92) 75.81 ± 4.10 (73.63–77.99) 0.549
SBP (mmHg) 129.12 ± 8.10 (124.80–133.44) 129.62 ± 6.74 (126.03–133.21) 0.843 131.00 ± 6.93 (127.31–134.69) 128.25 ± 6.40 (124.84–131.66) 0.221 125.62 ± 6.90 (121.94–129.30) 131.62 ± 9.33 (126.65–136.59) 0.031
DBP (mmHg) 81.75 ± 3.00 (80.15–83.35) 81.62 ± 3.28 (79.87–83.37) 0.926 81.62 ± 9.24 (76.70–86.54) 83.00 ± 3.58 (81.09–84.91) 0.239 82.62 ± 2.39 (82.35–84.89) 83.50 ± 4.23 (81.25–85.75) 0.379
Abbreviations: CI, confidence interval; HD, high dose green coffee extract; LD, low dose green coffee extract; PL, placebo; BMI, body mass index; HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; M, mean; SD, standard deviation.

Based on the numbers above, how did the authors of the paper conclude “Significant reductions were observed in body weight (-8.04 +/- 2.31kg)” (p.21), which equates to 17.69 lbs? I am confused on how they got to this calculation. The numbers that are in the table and in the paper do not add up to their conclusion number.

Obviously this “17lb” number from the conclusion is the number Mr Duncan used. This number also equated with the “loss of 10% of bodyweight” statement which is actually shown in the Chart 1 on page 22 (the average weight  of the study participants was 169lbs). So Mr. Duncan did not make these numbers up per se, but based the data in the  paper they are not correct and way overstate the  results. Did Mr Duncan actually read the whole paper? It is actually relatively short, just a couple of pages contain the pertinent information, so 10 minutes of effort would have likely lead to a better understanding of the results (see my above calculations).

Why does he recommend 800 mg 2 x day, so 1,600 mg/day? Where did this amount come from. It certainly did NOT come from the above study as the HD arm used 1,050mg/day, which is the largest dose every used with humans, see below (Onakpoya et al).

Mr Duncan’s emphatic “Sugar turns into fat” statement really has nothing to do with this supplements ability to make you lose weight. Also, this statement is really NOT true. As much as I think a lower carb diet can be useful for weight loss for many people it is NOT because “sugar turns into fat” or that carbs, which causes an increase in insulin secretion, actually inhibits fat loss (Guyenet).

Finally, the supplement “increases fat use in the liver” may be true (Onakpoya et al), but is really meaningless unless there is some level of calorie deficit created through a decrease in intake and/or an increase in expenditure.

Before moving on to my conclusion, I want to highlight a few things from a recent review paper on green coffee extract as a weight loss supplement. Click HERE to read it. This paper was published in 2011, so it was likely available BEFORE the show. The authors only found 3 human studies that fit the quality criteria. These 3 studies were published in 2007, 2009,and 2006,which means they were all definitely available BEFORE the taping of the show. Therefore, they could have been reviewed by Dr Oz or his staff and Dr.Duncan.

From the abstract of the paper;

“The purpose of this paper is to assess the efficacy of green coffee extract (GCE) as a weight loss supplement, using data from human clinical trials…Five eligible trials were identified, and three of these were included. All studies were associated with a high risk of bias. The meta-analytic result reveals a significant difference in body weight in GCE compared with placebo (mean difference: − 2 . 4 7kg; 95%CI: − 4 . 2 3, − 0 . 7 2). The magnitude of the effect is moderate, and there is significant heterogeneity amongst the studies. It is concluded that the results from these trials are promising, but the studies are all of poor methodological quality. More rigorous trials are needed to assess the usefulness of GCE as a weight loss tool.”

From the 3 studies included, there was an average of .6lbs of weight loss per week from the use of the GCE supplement. Not bad. This amount is about the same as the results from the most recent study (Vinson et al) which was the one being referred to in the Dr Oz show. Interestingly, the dosages in these trials where only 180mg/day, 200mg/day,and 200mg/day,much less than the amounts used in the most current study.

Mr Duncan states that roasting coffee beans eliminated the chlorogenic acid (CGA), possibly one of the main chemicals found in coffee beans that can elicit the weight loss effects. However, the review paper by Onakpoya et al states “The daily intake of CGA in persons drinking coffee varies from .5 to 1 g” (p.1). From the current evidence, that range of intake would likely be enough to elicit the potential benefits from CGA. Therefore, from what I can tell Mr Duncan is wrong about the content of CGA in roasted coffee.

This supplement does seem promising for weight management. I am not shocked as Matt and I stated in our book that we thought caffeine and coffee were likely to be useful for weight management. So my problem is not with the use of this supplement, but with the unnecessary hype and lack of a critical view of it taken by Dr. Oz and his guest. Here is the conclusion, which I agree with, from the review paper on GCE;

 ”The evidence from RCTs seems to indicate that the intake of GCE can promote weight loss. However, several caveats exist. The size of the effect is small, and the clinical relevance of this effect is uncertain. More rigorous trials with longer duration are needed to assess the efficacy and safety of GCE as a weight loss supplement.” (Onakpoya et al)

Why was this type of realistic view not presented on the show? Dr Oz has repeatedly misrepresented the facts on supplements, see Matts posts HERE,  HERE and HERE. What’s the deal Dr.Oz? I thought you were all about giving your audience and viewers the most up-to-date evidence-based information. Read these post for more on that topic, HERE and HERE.  To me, it looks like Dr Oz is selling out and that’s why I have lost a lot of respect for him.



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61 Responses to “Dr Oz Loses More Respect! Part 1 – Green Coffee Bean Extract”

  1. lily says:

    I totally disagree with you. I am from Australia, a fan of Dr.Oz. After Dr.Oz show with the help of green coffee beans, i lost 7kg in 3mths. Maybe i could have lost more if i had kept taking it but i dont want to look like coat hanger or anorexic model. Those excess fat, though being in healthy weight range, was due to unhealty life style for about 6mths; coke, muffins, red meat, kfc, mc.donald, pasta, pizza, processed packed supermarked food.I trust Dr.Oz’s recc and advise yeti make my own mind at the end.

    • Matt Schoeneberger says:

      So, you kept eating the same unhealthy foods and added GCBE? Or did you also start eating a better diet when you started GCBE?


    • brenton says:

      Why did you bother listing red meat with all that other crap? Didn’t you know that to metabolise fats the body must also utilise carbohydrates, therefore if one ate red meat and limited carbohydrate intake they would be substantially better off.
      Red meat is just as bad as white meat.

      Here is the reality, I was not trying to lose weight. I went onto my own food plan that cut out any processed food (I later discovered a group of people came up with a diet like mine called the paleolithic diet).
      I ended up losing 3 kgs in around 3 months, having 2500-3000 calories in my diet, exercising 5 days a week. I was trying to gain weight because my bodyfat was already down, yet by eating well I came out on top. Now my weight is increasing, thank goodness.
      The entire green coffee bean idea is stupidity when if someone has the determination they can achieve results. Dieting alone is a turnoff because exercise gives you a greater sense of achievement. My mum and uncle are proof of this, they both went off processed foods, wheat products and limited their carb intake. They are fitter than ever with no supplements other than good eating habits and exercise.
      Odds are this green coffee extract either:
      - Speeds up your metabolism and makes it less energy efficient leading to increased energy consumption or the generation of a caloric deficit. This means when you get off it your metabolism will revert back to its original form thus you will regain the weight if you don’t adopt healthy eating habits.
      - It may act as a laxative causing food to pass straight through you, leading to a starvation effect. This is dangerous as it can lead to multiple problems such as malnutrition.
      - It may simply act as a stimulant to promote weight loss, this is fairly obvious.

  2. Great post! For the longest time I have been letting my clients know how full of $#!+ Dr. Oz is. He does not have the ability to look at things from a non-objective viewpoint. Everything now is all about his opinion or that of a tiny select few. The best episode I watched was when a PhD in Exercise Physiology from Arizona was on there (I forget his name), and land basted Dr. Oz for not promoting fitness to overweight/obese people until they lose the weight. And in regards to GCBE, not that I am an expert in this specific area…shocking news! Coffee and caffeine promote weight loss….wow! But, unfortunately most of North America follows his material like a sage and never really get the real deal. Great stuff guys. I will definitely be promoting your site.

    • Darlene says:

      You are full of crap sir !! I take dr oz advice and it works for me why dont you get a life..

      • Aman says:

        Aww poor Darlene! Somebody happened to criticize your Pope/Deity/Religion/Pop-star, Dr. OZTurk, and like any insecure immature (religious) fanatic you go hysterical. Really pathetic you dumb groupie; the gentlemen who wrote this article based his arguments on FACTs taken straight of the study Dr. Ozturk was quoting. Whereas you are basing your insults on feelings and your insecurities that if Dr. Oz is wrong about some of his over-enthusiastic (insider-trading?) claims, that somehow that will undermine your hopes of leaving current struggle with blimphood behind and getting healthy. Coincidentally, I was puzzling over the exact same point about the discrepancy in the studies data that seems to show only a 7.84 lb (POUND not Kilogram) loss over 12 weeks and yet the report an 8.02 Kg loss in this conclusion. Something doesn’t make sense in this study. You’d think that a show with budget and manpower such the OZ Show would contact the study authors to get that cleared up before going on air and making erroneous claims? Did the study authors make a units error? mixing up Kgs for lbs? These are questions that need to be answered before jumping to conclusions.

  3. Sean Williams says:

    Well, I’m not a Dr Oz watcher, but, like you, one day I happened to tune in and it was the day he was hyping the GCBE. I’ve been on a strict diet for quite a while, losing an average of 3/4 pounds per week for the past 3 months. I know EVERYTHING I eat and the full breakdown (fat, protein, carbs, everything). So I figured I would be able to give this product a try for two weeks and have a GOOD idea if it works. Everything else being equal, and it WOULD be equal, if the GCBE works at all, I’ll see an increase in my weight loss. I figured if my weight loss doubled that would be GREAT, but even if it only increased from 3/4 pound to 1 pound, that’s evidence enough. And if there was no change, then I could tell my clients, friends, etc., that this stuff definitely does not work.

    Right now I’m on day 4. I am only weighing myself one time per week, Monday Mornings at the same exact time, same location. I can report back if anyone is interested in the results this coming Monday and the next.

    Oh, and Joe Chabassol, it’s not “land basted” (Is basted a word? How does one bast land? And what does basting land have to do with criticizing someone?) it is LAMBASTED, all one word. The “lam” is from the same root word as “lame” and “bast” an English word for whip or flog. Our word “baste”, as in baste a roast, originates from the same source. So lambast is the combination of lame+beat, or to make lame by beating. Hopefully from now on you’ll never write about basting land when you mean criticizing… And yes, I know, nobody appointed me the spelling police! And yes, I know, I’m a jerk.

    • Matt Schoeneberger says:

      I’d love to hear what you find out. Report back if you think of it.


      • Sean says:

        Well, I went through 3 bottles of
        GCBE and believe I was very consistent, followed the guidelines, and gave my trial adequate time (6 weeks) to show results. My results? Either no
        effect from the GCBE at all, or a slightly NEGATIVE effect! I’ve
        been dieting and losing about 2-3 pounds per week for several months. Very consistently losing an average of a little over 2 pounds each week. When I added in the GCBE, my losses became erratic. One week I might show no loss at all, the next 3 pounds. Overall, during the GCBE trial my weight loss slowed down by about 50%. Since cessation of
        the GCBE I have resumed my standard loss of about 2.5 lbs per week.

        I started my diet about 4-5 months ago. At that time I
        weighed in the 230-235 range. Now I’m down to about 205. I estimate my bodyfat percentage at 10%.

        Maybe GCBE works less well for leaner, well conditioned athletes? If it’s effects are metabolic – speeding up the metabolism – there probably just isn’t much impact that can have on someone who’s metabolism is already running on all 8. But for someone out of
        condition and carrying a much higher bodyfat percentage, maybe it does
        work. I’m not ready to say it’s a bust just yet for this reason (speculation).

        Interestingly, it seemed that, at least for me, the GCBE had SOME kind of impact on my metabolism, not necessarily positive. It may have even helped my body save fat. Something was going on, I just can’t say what exactly without having done more precise body composition testing.

        If asked whether I recommend GCBE, I would
        have to say no. I have concerns about ANY supplement that temporarily artificially alters the metabolism. There may be longer term consequences we might regret. I would recommend good
        old fashioned exercise and strict adherence to something like the Paleolithic diet instead of Dr. Oz’s magic pill.


        • crissyab says:

          well I’m giving it a try, I should have been losing weight for weeks according to my calculations and I’m not. Maybe it’s at least my magic pill and will work. I found some problems with the original broadcast, and this post, but I will see for myself. If anything budges my weight I will know it works,

    • Jeff Thiboutot M.S. says:

      How did your first week go?

    • Kurt says:

      how did it go?

  4. Helen says:

    I too was taken in by Dr. Oz and I beleived everything he says, but now I know better. Don’t get me wrong I like Dr.Oz but I think he pushes too many supplements that don’t really work. I have been taking the gbce now for one month and I have yet to lose a pound. I did cut back on eating sweets which is my problem and I do eat healthy foods but nothing changed. I’m not a big person I’m 5’7″ and weight 155lbs. I’m just trying to lose about 15 lbs. can’t do it with this that’s for sure. So for those of you that says it works good for you it didn’t work for me.

    • what Dr. oz said did not go for me either, have a my bottle halv empty and not 1 pound down, I’m a Veagn and eat healthy, no junk food and like to lese only 10 pounds, who is getting down ???
      One more lie!

  5. angie says:

    I too tried this supplement and actually had no loss.I took the supplement for 2 months,60 days and lost 6 pounds total. I have been on weightwatchers for 6 months and was losing 6-7 pounds a month. I am seriously overweight and want to be healthy. I now exercise for one hour 3-4 times a week and am starting to enjoy life. I was looking for something to help my thyroid problem as I don’t want to take pills for the rest of my life. Losing weight and getting healthy is the hardest thing I am attempting to do in my life,which is funny as I am a mother of 4 and life is crazy lol. I really thought by taking these pills it would jumpstart my weight loss but I now know I am the only one who can do this. So to all of you out their that want that magic pill,it doesn’t exist! I am happy it worked for some people,I think I will stick with the my exercise and eating healthy. Goodluck to all and have a great day!

  6. mrs jones says:

    I have been taking green coffee bean extract for awhile now and it works wonders. The first week i started i lost 6 pounds, may i add with no exercise nor any change to my eating habits. The thing we must also consider is regardless of what documentations may state…no one person body is alike, so what may work for you may not work for me and vice versa. So with that said, i also say this, dont assume or state that a product does or doesnt work just because it did not suit your own needs. Thank you and GOD BLESS

  7. Bronwyn says:

    This article is AWESOME! It is the only unbiased commentary on this supplement that I was able to find on the entire Internet. Thanks for your honest and intelligent evaluation! I’m definitely going to look around your site more as I am sure there is more interesting and helpful information!

    • Matt Schoeneberger says:

      I know Jeff is a little preoccupied and might not see this comment soon, so I’ll just chime in and say thank you for that. It’s nice to know our work is appreciated – it’s what makes doing this worth it :)

      Thanks again!


  8. owayhappy says:

    This maybe a stupid question but is everyone sure they have the right kind of GBCE supliment? So many people have said they see a difference. I’m curious of the kind of brands Everyone is using. There has been a lot of GBCE on the market that claim to be Pure and have 50% Chlorogenic Acid, but when the label is looked at real close it wasn’t the right stuff. I am very skeptical about taking any kind of pills. I am very concerned of the long term damage something maybe causing my body, however if it is a beneficial thing I would love to take something that is going to help my body be more healthy.

    • Matt Schoeneberger says:

      Read labels carefully and try to find supplement companies you trust, instead of just buying whatever is on the shelf at the local supplement store. There is always a chance with supplements that a product is not formulated correctly which is why it’s very important to educate yourself on the active ingredients and then identify them on the label.

  9. Brent says:

    Hi Everyone! This is Brent from Pure Health. We are one of the Pure Green Coffee Bean Extract brands recommended by Dr. Lindsey Duncan. Many of you may have spoken directly with me over the past few months on our facebook page, other social media or on the phone.
    I have been reading the comments posted here. There seems to be a group of people who are not having the same amazing results that so many people are experiencing. I am sad to say that there are businesses that are selling products that do not contain the crucial 50% or more chlorogenic acids. These products are not helping people to manage their weight whatsoever. They are mostly filler and binding agents designed to cash in on this wonderful substance.
    Are you sure that you are taking a product containing 50% or more chlorogenic acids? Please read this: Not all Green Coffee Bean supplements are created equal, give yourself a fair chance and start with a quality product.
    If you would like to speak with me directly or one of our amazing nutritional consultants about the Green Coffee Bean Extract, or if indeed you are taking a product that contains at least 50% chlorogenic acids just give us a call at 1-888-323-9355. We would be happy to answer any questions you may have.

  10. B willie says:

    I believe we could greatly improve health and the economy if supplements were regulated. If I have a tablet that is said to contain a certain active ingrediant where can I go to quantify the chemical. That is what consumers need quality control that is easily assesible. Legislation or the law today protects companies from consumers

    • Matt Schoeneberger says:

      I think it’s important to find reputable supplement companies that don’t give in to trends and fads, but instead make supplements only after a large amount of quality research establishes a benefit. When a company makes its reputation a priority, I have no problem trusting that the ingredients are legit.

      Also, a consumer advocacy group could test popular supplements and report on them. I’d favor this over regulation, as I tend not to trust those who regulate (not inherently, only because they have routinely screwed the pooch). Actually, Jeff and I have been talking about a little project regarding this lately :)

  11. Roma says:

    I’m a molecular biologist and medical writer. I took a look at the Vinson, J et al article, although admittedly, I skimmed it, preferring to look primarily at the methods, graphs, and tables. Here’s what I think you missed in your analysis of the study. First of all, the groups were divided into 3 treatment arms. Each arm received high dose (HD), low dose (LD), and placebo dose (PL), but in different sequence with a 2 week wash out period in between (HD/LD/PL, LD/PL/HD, PL/HD/LD). In other words, every participant in the trial received GCBE at some point in the trial. In between each 6-week trial dose segment, participants took a placebo for 2 weeks if the compound was administered at either dosage in the preceding segment. It appears that a washout period was skipped if going from PL to either HD or LD.

    As would be expected in this type of trial, overall change in body weight and BMI that might occur because of the compound use could end up being negated during the PL and washout periods, so what’s really important is to look at the weight lost during either the HD or LD segments of each arm, and determine if that loss is statistically significant. Statistical significance is NOT the same as what the average person thinks of as significant. It means that the effect that was noticed could not be attributed by chance. Statistical significance is shown in the P column of the table you reproduced. A P value <0.05 is considered to be statistically significant, and the P values clearly show that the weight loss observed during the treatment phases were statistically significant, whereas during the PL phase was not.

    Now, if you look at the graph presented in Figure 1 of the paper, it is very clear that there was substantial weight loss during each period of treatment, but not during either the washout or PL phases. Bearing in mind that these are average changes (meaning that some people lost more weight during each phase while others lost less), it appears that during the HD phase, mean weight loss was ~7 Kg (~15.4 lbs) for the HD/LD/PL arm, ~4.5 Kg (~9.9 lbs) for the LD/PL/HD arm, and ~5 Kg (~11 lbs) for the PL/HD/LD arm. That still doesn’t quite account for the mean 17 lb loss until you factor in loss during the LD period of each arm: ~1.5 Kg (~3.3 lbs) for HD/LD/PL, ~4 Kg (~8.8 lbs) for LD/PL/HD, and ~1.5 Kg (~3.3 lb) for the PL/HD/LD arm. In other words, total weight loss while taking the supplement averaged ~18.7lb for the HD/LD/PL arm, ~18.7 for the LD/PL/HD arm, and ~14.3 lbs for the LD/PL/HD arm, which creates a mean weight loss of 17.5 lbs during the overall drug phases of the trial.

    In my opinion, the protocol for this study was well thought out and correct for the type of analysis they were trying to achieve, although the sample size was low, as would be expected of a pilot study, although without conducting an actual power analysis (that is, determination of the number of participants needed and the extent of change to reach statistical significance/dose), I would say that the study is adequately powered for a pilot. Certainly, this study should be repeated with a much larger population.

    As an interesting note, Dr. Oz ran a “follow up” study of his own for the show which aired yesterday. The protocol was satisfactory for a simple pilot study, and used a reasonable evidenced-based approach. His study evaluated ~100 women between the ages of 24 and 48 and diverse ethnicity who were nondiabetic, free of heart disease, not pregnant or lactating, and only moderately overweight (preobese, as in the Vinson study). One thing he did NOT control for was euthyroid, which would have been a wiser choice. His study ran for only 2 weeks, and employed a simple 2 cohort model (drug vs. placebo). The drug group averaged a 2 lb loss over 2 weeks, with some subjects losing as much as 4 lbs, while the placebo group averaged only 1 lb in the 2 weeks. No real statistical analysis was conducted (hey, it’s TV!), but the results at least appear to be promising.

    Gentlemen, I appreciate your analysis, but going forward if you are going to analyze papers of this nature, I highly recommend that you read “Studying the Study and Testing the Test” by R.K. Riegelman. It will give you far better insight into how to analyze different types of studies and pull the most benefit out of medical journal articles.

    • Matt Schoeneberger says:

      First, I don’t know if you mean to be condescending, but we’ve both read tons of journal articles and our understanding of statistical significance is just fine. Thanks for the book recommendation, though, as it can never hurt to bone-up a little.

      Your interpretation of Figure 1 is odd to me:

      “Now, if you look at the graph presented in Figure 1 of the paper, it is very clear that there was substantial weight loss during each period of treatment, but not during either the washout or PL phases.”

      Actually, for the HD/LD/PL group Figure 1 shows a straight, down-ward sloping line from point 1 to point 3 (Initial, week 6, week 8), which would indicate weight loss during both the HD and following washout period. In fact, since the wash-out period is only two weeks but the graph is evenly spaced for all periods, this would indicate the same amount of weight was lost during the 2-week wash-out period as the 6 week HD arm. And, this would also indicate that you are including the wash-out period when you say “Bearing in mind that these are average changes (meaning that some people lost more weight during each phase while others lost less), it appears that during the HD phase, mean weight loss was ~7 Kg (~15.4 lbs) for the HD/LD/PL arm”

      Maybe you shouldn’t have skimmed the study. Maybe you should have read it carefully and then read the others. Your interpretation of the study design is incorrect. The wash-out period is just that, a wash-out period. No placebo is given during the wash-out period:

      ” Subjects stayed on a treatment for a period of 6 weeks, followed by a 2-week washout period, before the next treatment period began.” They don’t have a wash-out period after the final 6-week treatment period because that would be pointless.

      Tell me, does medical writer mean clinical marketing specialist?

      • Roma says:

        Hi Matt,

        Sorry — I did not intend to be condescending — my apologies. I noted your and Jeff’s degrees and expertise, but felt that you had misunderstood some points. Afterall, you did pose the question of how the authors came to their conclusions, which is what I was trying to elucidate.

        I agree, it would be far better to have read the study in depth, but I have so much on my plate I just don’t have time. When I get a moment to breathe, I’ll look at it again and reconsider. I do think my interpretation of the wash-out period and interpretaion of Figure 1 is correct, however, whether or not a placebo was given during the wash-out period. In controlled drug trials, often a placebo is given throughout the wash-out period so that the subject doesn’t know which phase of the trial they are currently in. In this case, all three arms end simultaneously because each enters it’s respective wash-out period at a different time, depending on the phase of the trial. I think the x axis legend is a little misleading, as it seems to suggest all patients were in wash-out at the same time. I don’t think they were — I think (still just looking at the graph and not the text), that each entered wash-out ONLY after a drug trial period. This is the only way that the data make sense to justify the authors’ conclusions.

        BTW, I am not trying to justify Dr. Oz. I used to enjoy his show, but it has degraded considerably since he took over Oprah’s spot, which is a shame. He used to be so good at explaining complex medicine to the average person, but now seems to just spout alternative medicine, much of which is based on dubious studies or improper extrapolation. For instance, last year he claimed that raspberry ketones had be proven effective for weight loss. Right. There were two studies, both conducted in mice. Mice are not humans, and you can’t extroplate results from animal studies to humans, especially mice! I don’t know if you recall, but several years ago studies on the function of LBP in sepsis were conducted in mice, after which it was deemed safe to repeat the study in humans. Several of the subjects ended up in ICU, and I think at least one person died. Dr. Oz should know better, but I imagine he answers to his producers first, and the Columbia Presbyterian Medical Ethics Board second. Too bad.

        As for your other question, Clinical Marketing Specialist is simply a title used by my company to assign a pay scale. As a medical writer, I spend my days interpretting data from clinical trials to write articles for medical journals. I am NOT a ghost writer, before you should suggest that, as I appear as either an author or in the acknowledgements of every article I write, depending on my level of intellectual contribution to the article, per the ICMJE and WAME guidelines. I also create deep-dive educational materials for live presentation and video production.

        You’ll like the book. Even after spending years doing primary research, I find it to be very helpful for review and explanation, especially when looking at the specialized statistics used in the medical and diagnostics literature. (…oh yeah, PPV isn’t as simple as it looks and *does* require me to factor in prevalence… (-: )

        • Matt Schoeneberger says:


          Thanks for responding. I understand better where you’re coming from now and I apologize for being a bit snippy in my first response.

          As for Figure 1, I’ve tried to see it through your interpretation and it just doesn’t fit for me. I don’t see, for instance, how the HD/LD/PL group lost about 7 kg during the HD phase. It looks to me like that group goes from about 78 to about 74 kgs from point 1 to point 2 (initial to week 6). I can guess the main difference is you’re trying to justify the authors’ conclusions and I’m not. To me, either the authors have included weight loss during the wash-out period for their big number conclusion or they’ve innocently made one of the most misleading line graphs known to man, LOL.

          We’ve got another post floating around here somewhere on RK.

          Dr. Oz should know better, but I imagine he answers to his producers first, and the Columbia Presbyterian Medical Ethics Board second. Too bad.

          It’s a shame. He’s got a huge audience and a real chance to encourage people to make meaningful, long-lasting changes. I don’t blame him, really, but the audience since they’re not really looking for anything other than the magic bullet. If it wasn’t Dr. Oz promising it to them it would just be someone else.


  12. rudy says:

    from the report YOU linked to:
    “Significant reductions were observed in body weight (−8.04 ± 2.31 kg), body mass index (−2.92 ± 0.85 kg/m2), and percent body fat (−4.44% ± 2.00%), as well as a small decrease in heart rate (−2.56 ± 2.85 beats per minute), but with no significant changes to diet over the course of the study. Importantly, the decreases occurred when subjects were taking GCA. Body mass index for six subjects shifted from preobesity to the normal weight range (<25.00 kg/m2)."

    This contradicts your diatribe (normally well-deserved) against Oz.

    • Matt Schoeneberger says:

      Did you miss the part where this was quoted in Jeff’s article and then examined?

      “Based on the numbers above, how did the authors of the paper conclude “Significant reductions were observed in body weight (-8.04 +/- 2.31kg)” (p.21), which equates to 17.69 lbs? I am confused on how they got to this calculation. The numbers that are in the table and in the paper do not add up to their conclusion number…”

  13. Josie says:

    It seems there is a strange discrepancy between Table 1 and Table 2 in the results section that I would love any research expert to explain if you can. Table 1 shows mean starting weight at baseline and at end of 22 weeks, the starting average weight is 76.69K and at the end 68.65K so there’s the 8K loss, but in table 2, the average starting weight in each arm is about 72K. Where did the 76.69 come from? Why was the average weight 76.69K at baseline, but then 72K at the beginning of each arm? Confused?????

    • Matt Schoeneberger says:

      Hi Josie,

      I hope I can explain this well…

      In Table 1, you see the mean for everyone in all groups at baseline and week 22. In other words, the mean of everyone at their most likely heaviest and lightest. In Table 2, you see the mean of everyone when they started a particular dose (HD/LD/P). Some people started HD at week 1, some at week 8, and some at week 16. So, those who started at week 16 had already received both the LD and P treatments and were probably at a lower starting weight once they got to the HD treatment. This is what makes the means in Table 2 lower.

      The discrepancy is compounded by the fact that they included the wash-out periods in some totals. Looking at this data still makes my head spin, haha. Figure 1 is the most intriguing to me. No matter how you slice it, some people were losing weight during wash-out periods and it looks like this weight loss was included in the totals for the preceding treatment. Weird.

      All-in-all, the WOW factor just isn’t there for me. Why not just use some good old wicked-cheap caffeine for some thermogenic boost?


  14. Josie says:

    Okay thanks Matt. Appreciate the explanation. I’m trying it and on day 3. I have what I believe to be some hormonal weight gain (about 8 pounds) and no matter what I do, the scale isn’t budging so I was interested to see if it can make a difference. I’m gonna try it for a month and see what happens. Truthfully, I’d be happy with 3-4 pounds. I’m not looking for any miracles. I will keep you posted.

  15. Lynn says:

    Sounds like the latest “hoodia” to me. Too bad the crooked, souled-out Monsanto/Big Pharma shills at the FDA took away the only thing that worked (Ma Huang Ephedra) while leaving us stuck with all this useless quackery promoted by their front-man shill, Dr. Oz. All because 1 or 2 athletes supposedly died from ephedra (who drank copious amounts of highly TOXIC aspartame, which turns to embalming fluid in the human body and which is completely recommended by the FDA scoundrels). They treat the other 20 MILLION people who took ephedra successfully like helpless little children who don’t know how to take anything responsibly without Big Brother FDA there to tell us what we can have and can’t have. And of course they won’t mention that over 200,000 people annually die from side effect of their approved Big Pharma quackery/sorcery. The one’s selling this junk are probably the same 1% who have stolen over half the weatlh and resources of the entire world and who bought out the FDA puppets. They took away what worked because they want a fat and sick cash cow, while still preying on people’s sheer desperation. They corrupted our food supply with high fructose corn syrup, msg, aspartame, nutrionally depleted “pasteurized” (aka DEAD) food and genetically modifed fruits and vegatables that contain insect dna. People are STARVING and OVEREATING because they are nutritionally bankrupt. What a crock.

  16. Mario says:

    I would guess this product would work best on people who have metabolic syndrome. People who have high levels of insulin in their blood to help keep blood sugar down into the normal range tend to be pre-diabetic. This product probably does not work nearly as well for people who do not have this problem. a little common sense I think goes a long way.

  17. Vanessa says:

    I have been taking The real pure one that I got on amazon and have been losing 2 to 2.5 pounds every week. I kept the same diet and exercise routine !

    • Matt Schoeneberger says:

      Good for you, Vanessa! Would you mind sharing some other stats if it doesn’t bother you? Current weight/height? 2-2.5 lbs is a lot so some perspective might help others decide what they might see.

  18. Tina says:

    I purchased a brand at GNC Camada which contains 350mg. I took 3 times a day.
    i used it for 2 weeks and added a brisk 45 minute walk 7 days a week. I eat “low carb”most of the time. I gained 4 pounds and bloated out to the tune of looking 5 months pregnant. So bloated i couldnt even breath most times after eating a small meal. I was getting quite concerned with my odd appearance. After that two weeks, i stopped taking it, continued my walk and my tummy is flatter then when i started, and i lost 3 pounds in two weeks after i stopped taking it.

    The bloating was so severe that i cannot recommend any green bean coffee product – i wouldnt want anyone else to experience that.
    question – is that common – why did that happen? Yes i drank 5 glasses of water a day (at least)

  19. Mac says:

    “So bloated i couldnt even breath most times after eating a small meal. I was getting quite concerned with my odd appearance.”
    Well it’s nice to hear someone with my issue!…But sorry for your experience,Tina.
    I have another issue that may be contributing to my bloating problem.Iam coming off a long term drug programme,a proces during which some folks do complain about bloating,but am well-along in the process,and it really shouldn’t be a problem.That said,the previous posts of scientific testing and analysis will not apply here!
    I got taken into the Oz fold about 3 weeks ago.I’m not one to jump on diet bandwagons,but thought I would give it a shot…20 bucks worth.
    All went well till about 5 days ago.Not that I lost weight,but there were no apparent side effects,I was eating less,and I did feel better…more energy,sleeping better,that sort of thing.Maybe lost 5 pounds….but that is a flucuation that many folks see in any given week…even 2-3 pounds from morning to night is pretty normal for me.
    So….I really didn’t think the stuff was doing anything,but carried on with it,hoping it might kick in at some point…might as well use it up,y’know?
    Then came last tuesday.Bloating like crazy!….I felt like I was having triplets…and the distension was very obvious.Odd for a man to be in this position;)
    A quick google turned up just a few results for GCB and bloating…..that’s how I found this place…..but it seems to be not common,but evident.
    SO…as of last evening,I have taken the last of the GCB.Will see in a day or 3 what effect this might have.
    Will get back here to post results for those interested.

  20. Mac says:

    Bloating issue pretty much gone within 36-34 hours of stopping GCB.
    Seeing as there were no other changes in either diet or activity,I would suggest this,for me at least,is fairly conclusive.

  21. Lala says:

    How you gonna know what kind of green coffee to buy coz there’s so many website out there that are selling green coffee

  22. Mark Ketchum says:

    hmmm… listen to what you are saying about nutrition and alternative medicine… or listen to Dr. Lindsey Duncan with over 3 decades of study and formulation with huge positive results? If you weigh it… if you truly weigh it… hmm… maybe to step back a little and look at it from that angle… hmm…. yep… I think I will listen to Dr. Lindsey Duncan. Oh, and since I have seen hundreds of stories of weighloss from people I personally know who have prescribed to his methods… and I have actually met Dr. Lindsey Duncan and attended one of his conferences and heard his Ph.D type 3 day thesis on nutrition and the environment… I think this man is the real deal and has nutritional science in the bag. You make the choice.

    • Mark Ketchum says:

      Oh… and in the 3 months I have been using Green Coffee Bean with CA and Black Pepper Extract… I have gone from 298 lbs down to 272… and I continue to lose. And this has been a struggle of mine since my mid 30′s and I am 46 now. I have more energy and yes… I have altered my diet and exercise regimen… but I did that before and did not lose as fast, nor did I maintain it because I didn’t stay motivated r/t my slow results. I say give it a try.

  23. LD says:

    I must say, Dr. Oz does seem like he’s shilling for Big Pharma, etc, at times, by virtue of his omissions and the like, in a sort of controlled opposition capacity. I do not care for this type of spokesperson personally, and it is sometimes irritating when people try some “new, amazing” herbs, remedies and/or techniques at his recommendation when he is actually, simply, sharing valid things, like in the natural arena, that have been known and worked for a long time– but only because he said it will people (who formerly pooh-poohed others saying the same thing) jump to it. *sigh* I guess in the end all that matters is people become aware of the power of natural healing, etc, when he does hit on the proper usage/info, but still . . . his guru-like hold over some is a bit off-putting. I am familiar with the work of Stephen Guyenet as well, great stuff.

    That said, I researched a little for any harmful effects and decided to try the GCB after getting one of those emails that promise amazing results. I actually got the one I saw @ Sam’s Club– the Pure Health brand. I did not know at the time it was the Dr. Duncan one. It was reasonably priced and I did not want to spend a ton of $ for a trial.

    In the 1st week I lost 7lb, as advertised, and did not change a thing. Plus, I had become lax on my daily walking (30min) due to unforeseen events. I generally eat healthily, no sugar if I can help it, no white flour, and take vitamins and supplements. I just try to avoid processed food if possible but I’m not a fanatical about it. In the 5 or 6 weeks of taking it I’ve lost about 10-12lb. I don’t know, I don’t check anymore. I just know it’s helped me lose excess jiggle that had been taking a while to burn.

    Just my two cents, hope it helps some still searching to come to their own informed decisions.

  24. Sam says:

    Dr Lindsey Duncan has 29 years and 40,000 hours of research under his belt. He won a Vity Award back in the 90s for a lesser product.

  25. George says:

    Special diet? Bullshit

  26. JC Moreau says:

    You did not compare apples to apples and still you argument practically supports Dr. Duncan. There are so many variables that can be taken into consideration for these studies, but they cannot all be. I have dealt with this industry at the highest level of athletics for 15 years and there is very little I recommend. GCBE is one I do, it works.

    Why are you guys so bitter? Most “science” is tweaked to prove or disprove what you want to prove or disprove and if it does not try again. I don’t think Dr. Duncan did that, but your studies are random, use too little GCBE and the quality of it and whether they were the same is not mentioned. Hell you all may have had even better results than him, slapped your names on a bottle and bought a place on an island.

    There is SOOOOO much garbage out there. I appreciate your efforts, just the wrong product to expose.

    Good Luck,

    JC Moreau

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  33. homepage says:

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  34. Adelina says:

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