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Recruiting Volunteers for Weight Loss Study


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As a clinician, my primary goal is to help my patients. While I am fascinated by scientific theories, I am far more interested in whether those theories can be applied to practical solutions for the patients that I work with.

I feel grateful for this perspective, because I believe it helps me to keep an open mind and not get too attached to one theory or another. My patients are constantly teaching me that no matter how good a theory or hypothetical treatment is, real live people sometimes do not respond in the ways that textbooks or studies tell us they should.

When I first read Stephan Guyenet’s series on the role of food reward and palatability in fat gain, I was intrigued. As far as I know, it’s the only theory of weight regulation that can embrace and explain all of the other prevailing theories. For example, food reward can explain why both low-fat and low-carb diets can be effective for weight loss on a short-term basis, and provide insight into why they often fail over the long-term.

Another reason it appealed to me is that I have a number of patients that have tried numerous diets (low-carb, low-fat, Paleo, ketogenic, etc.), but still haven’t lost the weight they’d like to lose. I can’t help feeling curious about whether reducing reward might be of benefit to them. (Note: we will not be testing that particular hypothesis in this study. See below for details.)

Stephan has outlined a substantial body of evidence supporting the role of food reward/palatability in fat gain, and some suggesting that reducing it can be helpful for fat loss as well. But what we’re missing is a study evaluating the possibility that reducing food reward (without resorting to liquid diets) can be a practical fat loss strategy in free-living people.

To remedy this, Stephan and I designed a randomized, controlled food reward fat loss trial. But we’re still missing one thing: volunteers! Please read the study design and volunteer criteria below. If you’d like to apply, click the “Volunteer Application Form” link at the end of the post.

Study design

We’re looking for twelve overweight/obese volunteers (men or women of any age) who would like to eat a low-reward diet for one month, in the name of science. The diet will focus on simple, gently cooked food, and minimize flavorings including salt, herbs and spices, added fats and added sugars. It will also minimize flour products, which have a high energy density and tend to be highly rewarding/palatable. It will strive to leave macronutrient ratios (carbohydrate, fat and protein) unchanged. The control group will be asked not to change diet or lifestyle over the course of the month. Volunteers will be asked to report body weight and waist circumference measurements, and fill out two short questionnaires (adherence, hunger, well-being, etc.). Data will be analyzed and reported publicly, but they will be reported in a 100% anonymous manner.

Since this is a randomized trial with an experimental group (n=7) and a control group (n=5), each volunteer will have a 58 percent chance of being selected for the experimental group, and a 42 percent chance of being in the control group. Unfortunately, the nature of a randomized trial means you don’t get to choose which group you end up in, but that’s a critical element of the study design for statistical reasons.

One limitation of this study is that if we do see fat loss in the intervention group, we will not be able to conclude that food reward/palatability is the critical factor, since other variables may change at the same time (e.g., sugar). We don’t have the resources to conduct a study that alters nothing but reward/palatability, which would require an experimental kitchen, a professional staff and local volunteers. However, our study will be able to answer the question “is advice to reduce the reward/palatability of the diet useful for fat loss”? It’s more of a practical question than a mechanistic one.

Volunteer criteria

Here are the criteria you must meet to qualify:

  • must be sufficiently motivated to complete a one-month diet trial
  • must carry substantial excess body fat (25+ lbs / 11+ kg excess fat). This correlates approximately with a body mass index of 25 or more in a person of average muscularity (BMI calculator: http://www.nhlbisupport.com/bmi/)
  • must have an accurate scale and a tape measure
  • must eat mostly food cooked at home
  • must not rely heavily on processed convenience food and restaurants
  • no diagnosed endocrine disorder (diabetes, hypothyroidism, etc.)
  • must not currently be weight reduced relative to a prior weight
  • must not currently be on a weight reducing diet (low-carbohydrate, low-fat, Paleolithic, Zone, Ornish, etc.)

If you meet all of these criteria, please click the link below to volunteer for the study. If you don’t meet the criteria yourself, but have a friend or family member that might, please forward them this post.

Volunteer Application Form

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Join the conversation

  1. This seems relevant to the food reward discussion. From an interview with Dr. William Davis:

    Q: You write that wheat is “addictive,” but does it really meet the criteria for addiction we’d use when talking about, say, drugs?

    A: National Institutes of Health researchers showed that gluten-derived polypeptides can cross into the brain and bind to the brain’s opiate receptors. So you get this mild euphoria after eating a product made with whole wheat. You can block that effect [in lab animals] by administering the drug naloxone. This is the same drug that you’re given if you’re a heroin addict; it’s an opiate blocker. About three months ago, a drug company applied to the FDA to commercialize naltrexone, which is an oral equivalent to naloxone. And it works, apparently, it blocks the pleasurable feelings you get from eating wheat so people stop eating so much. In clinical trials, people lost about 22.4 lb. in the first six months. Why, if you’re not a drug addict, do you need something like that? And of course there’s another option, which is to cut wheat out of your diet. However, and this is another argument for classifying wheat as addictive, people can experience some pretty unpleasant withdrawal symptoms.

    The full interview is here:

  2. Assuming you got 7 volunteers since e form is no longer avail? If no I meet all criteria and would be interested.

  3. Have you performed a power calculation?
    How are you randomizing your cohort?
    What are your endpoints?
    How are you going to match your controls?

  4. Paul,

    I never took thyroid meds and never will. It is a delicate system and I would let your thyroid figure it out.
    Some tips :
    – be sure to take adequate basics : selenium, iodine, zinc.
    – sleep ! (rise with the sun and go to sleep max 2 hours after the sun has set)
    – blue light for waking up and only amber light after dark
    – connect to the ground (‘earthing’ )
    – generally do LC, occasional carb binges and occasional zero carb days
    – do not eat your biggest meal in the evening

  5. Paul,

    maybe its the other way around ?
    Maybe we are all eating to many carbs and generally eating to much (and over-drinking coffee) because we are all trying to self-medicate our hypothyroidism ?

    Going low-carb fixes the weight gain but exacerbates the hypothyroidism so it is unsustainable.

    Maybe we are all to stressed out AND too low on selenium/zinc/iodine/… to keep our thyroids humming optimally on the modern lifestyle and diet ?

    • I’ve thought the same thing. My body somehow “knows” that protein (and fat?) makes my hypo worse, so I am driven to carbs (and, of course) coffee instead. I have been VLC, but recently allowed in fruit and potatoes and my weight has gone up 6 pounds which is very frustrating. I don’t think HFLC is unsustainable with hypothyroidism – instead the T4 / T3 dose may need to be increased. Also, I would blame protein instead of fat in the first instance – this is what Dr Broda Barnes says in his book. Finally, I think low cortisol is important for some of us – how can we do gluconeogenesis if it is low.

  6. I had lost some 20Kgs 2 years back, by dropping wheat, refined oils. Eating a higher protein lower carb diet. I did not and still don’t eat a low carb or a low fat diet. I am around BMI of 26, with a body fat percentage of around 22. I would have a bit more than 10Kgs of fat. I have not done serious dieting for fat reduction, but have been following a mostly non-toxic diet, for the last 3 years. We do cook everything at home, and eat rarely outside. I don’t have any thyroid or diabetes problems, but I do suspect my adrenals. Haven’t got it tested yet, because I procrastinate a lot (could these two be related :-). I guess I am a borderline case :-).

    Why are you only having only 12 people? I would think that you should take as many as possible. Are you going to do consultations, which might be a problem for a large number of people? But that makes me very very much interested :-).

  7. this IS exciting — it’s too bad i’m ruled out as a candidate for the trial, because i’d love to be a part of it! looking forward to hearing the results!

  8. This is very interesting!
    I am absolutely sure food reward has a lot to do with excess weight – though, leaving out flavour could easily lead to binges.

    • Another thing is: if people are capable of staying on a bland (or any other) diet, I don’t see how they would NOT re-gain the lost weight. People capable of staying on a diet for one month, though still obese, are most likely yo-yo’ing. I don’t see how the bland diet would be any different from other diets in that aspect. I don’t think many people would like to make bland meals a lifestyle. They will be very, very prone to binges.

  9. It is hard to keep up with everything on the various blogs, so I have formed some views and picked my Gurus. I have a thyroid / adrenal bias as I started there and I tend to assume that Dr Broda Barnes was right. In particular, that blood tests for thyroid problems are not-conclusive (signs, reflexes and basal temperature are more important), a combination of T4 and T3 is better than T4 alone and that sometimes supplementary cortisol is helpful as well. So, Dr Broda Barnes book “Hypothyroidism – The Unsuspected Illness” is important to me. This is relevant to diet because that book includes a chapter on thyroid and obesity wherein Dr Broda Barnes talks of success with a high fat low carb. He had no apparent problem with thyroid problems (say, low T3), but he did note that high protein diets did increase the need for thyroid hormone – perhaps it is the inadvertently increased protein in my initial low carb diet that caused the low T3 I experienced. The point is that I back the HFMPLC approach and suggest that both thyroid and cortisol status need to be assesses during studies – it is hard to stick to a diet when these hormones are crashing and you are getting poorly.

  10. I don’t know anyone who could meet the criteria for participation. Most “regular” people I know do eat at restaurants and eat prepackaged junk. No one cooks at home anymore. It’s very sad.

    I think it will be difficult to get enough participants who will actually adhere to the diet for 28 days. I’d do it, but, I just lost a bunch of weight via paleo/lc. Probably most people who read Chris and Stephan’s stuff are already trying to eat well. Good luck finding some participants. I hope I’m wrong and that you get a good response.

  11. Hi Chris,

    Sarah makes a valid point and this appears as more of a pilot study. But considering the fact that you are recruiting online and participants will be taking part in the trial at minimal work to yourself, except for data analyses presumably and being able to answer questions that may arise, I don’t see why you should not make this a larger scale trial from the outset and incorporate comparison interventions. In a similar vein to the Atkins/Ornish/Zone/Learn study by Chris Gardener it would only be examining the ffect of that particular diet approach and obviously not a single variable, but comparative studies offer far more insight than a simple 2 group RCT.

    Also, even if this is only a pilot trial, why only 12 participants? Have you cofirmed whether the sample size is sufficient to detect a difference based upon the effect size of the intervention? I’d like to know as one thing that annoys me most in RCT’s is that even in this day and age the majority do not provide power analysis calculations and justification for their sample size. If you haven’t because the data to calculate effect size isn’t already available then this can act as a nice pilot to determine it before moving onto a larger trial. If the data exists though it would be better to make use of it and go straight for a smaple size justified by it.

    Just my two cents. Looking forward to the results anyway.



  12. Hi Chris,

    I get the feeling this is a pilot study so I’m sure you’ve already thought of this, but I think it would be far more interesting to compare this to a VLC diet. We know they work short term, but this is a short term study. But here’s the kicker, make the VLC diet as rewarding as possible. Salt, spices, cheese, lots of added fat, hell add in free glutamate in the form of msg too. I think that would yield some very interesting results that a lot of the nutrition community would be very interested in right now.

    • Yes, i totally agree with Sarah and would love to see the differences between the two groups . . . and i would LOVE to be part of that second group 🙂 unfortunately i dont meet all of your criteria, but it would be fun to see what the diet is so we could follow along at home if we wanted to and see how our own results compare to what you found in your study groups. Either way, im looking forward to hearing what you find!

    • I totally agree! We need to compare this to a paleo style low carb diet that is very rewarding with spices, herbs, high quality fats etc.

      Looking at the diet that is laid out it seems have a low amount of food allergens, added sugar, a relatively low amount carbohydrate (compared to SAD), and increased blandness. Lets take out the blandness, if we want to truly test this food reward hypothesis this study needs to be redone to compare both a lower carb paleo vs food reward palatability vs control.

      My personal bias is that Stephan’s diet is impractical, I have a hard enough time getting my clients to eat paleo (which does provide phenomenal results). Now I have to have them doing something very similar with the challenge of having them make it extra bland…. good luck…but I am all for a study!