Book Review: Secrets From the Eating Lab

The Science of Weight Loss, the Myth of Willpower

Author: Traci Mann, PhD
Publisher: Harper Collins
Book Publication: 2015

“Diets don’t work, may be bad for you, and obesity is not going to kill you.” So says Traci Mann, professor of social health and psychology at the University of Minnesota, and founder of the Health and Eating Lab. In her well documented and engaging Secrets From the Eating Lab: The Science of Weight Loss, the Myth of Willpower, and Why You Should Never Diet Again, Dr. Mann shares what she has discovered in over twenty years of research into eating.

The book begins with a discussion of the science that proves diets don’t work, and why. To find out how effective diets were in the long term, Mann and her graduate students tracked every study that followed dieters for at least two years (average study length was 3.6 years), and that had used randomized control trials (the gold standard in research). Their findings: “After that time, dieters had managed to keep off, on average, a measly two pounds. Nearly half of the participants, or about 40%, actually weighed more at the follow-up than before they went on the diet.”

To understand why this happens, Mann says we need to look at human biology and psychology. Blame it partly on our genes because, as Mann explains, our genetic code contains the blueprint for body type and, more or less, the weight range that we can healthily maintain. Our body, she says, tends to stay in what she calls a Set Weight Range most of our life. Moreover, if our weight strays outside of this set range, a number of body systems work to push us back toward it.

Psychology features in the failure of diets as well. When people are dieting and hungry, Mann has found that the most common response is an obsession with food. This was a useful response for our ancestors during times of scarcity but today, as Mann suggests, it just means that the less we try to eat, the more obsessed we become with food.

When dieting, your brain also responds differently to tasty-looking food than it does when you are not. “The areas of the brain that become unusually active make you more likely to notice food, prompt you to pay more attention to it when you find it, and make it look even more delicious and tempting than usual.”

Excess weight is often attributed to lack of self-control, however thinking willpower is the key to weight management is misguided, Mann says. Studies show that self-control ability influences eating only half as much as it does for most other behaviours.

The evidence seems to support Mann’s position that diets do not work, but are they really that bad for you? According to her research, diets trigger a stress response which, if it becomes chronic, has been proven to compromise many crucial physical functions: immune system, reproduction, and energy storage. Dieting also causes cognitive impairment.  When researchers asked dieters and non-dieters to complete the same series of mentally challenging tasks, dieters could not remember as many words or sentences as non-dieters, and they reacted more slowly to stimuli when speed mattered. In addition, and most importantly, dieters experienced impaired central executive function. When this happens, your ability to plan, make decisions, solve problems, all of which are necessary for effective self-control, is adversely affected.

If not by dieting, how do we get to what Mann says is optimal – our leanest livable weight? She believes her twelve research-based smart regulations will result in people eating more healthy foods, without lots of effort and willpower required. One example: put obstacles between yourself and unhealthy foods. A study conducted at Utrecht University demonstrated that people ate less candy when the dish was across the room from them than when it was right next to them, making a distance of less than a few feet an effective obstacle that can help limit consumption.

To eat healthier foods such as vegetables, Mann advises you arrange to be alone with them. Start every meal with a vegetable (salads are simplest) before you eat anything else, because you will “eat more of it when you are at your hungriest and there are no other temptations around.”

This book is clever, persuasive, and entertaining. Mann challenges both the weight loss industry and obesity researchers, proving the way to living a healthier life is not through dieting. Her final advice: “Eat in a sensible way most of the time, without extensive rules or restrictions.” That seems a perfectly reasonable and reachable goal.


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Susannah Kent is a Toronto area Fitness and Healthy Lifestyle Instructor.

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