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.
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 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.
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.