This Is Why Eating Less Will Make You Gain Weight

Eat less and exercise more.

We’ve all heard it—from our doctors, on TV, on the Internet, in magazines, from friends and family—calories in/calories out is key to weight loss. At one time or another, most of us have even tried it. But let me ask you: How has this recipe for weight loss worked for you? It seems like such a simple formula—it matches our understanding of the physical principles of the universe. Energy in, energy out. What we don’t spend, we store. It’s common sense. It must be right. There’s just one small problem. It doesn’t tell the whole story of why people gain weight. And it doesn’t tell us how to lose it. The calories in/calories out theory of weight loss is outdated. Modern science has proven beyond any shadow of doubt that your weight and your health are dependent on much more than how many calories you consume.

However, common sense and personal experience tell us that if weight and health were all about the amount of calories you consume each day, you could eat 1,800 calories of Oreos and Diet Coke and stay fit and healthy. But, of course, we all know that doesn’t work. The food you eat has a far greater influence on your body than solely the amount of energy it provides. It has wide-ranging effects on numerous biochemical and physiological processes. While it’s true that most of us could afford to eat a little less, and reducing total caloric intake is necessary to a certain point to incur weight loss, the quality of the calories you consume is far more important in the long run.

That’s especially true if you want to burn fat and keep it off for good. Anyone can go on a starvation diet, burn out the treadmill, and drop a few pounds. You might even lose a couple of pants sizes or notice that you look a little better in your bathing suit. But the sad reality is that most of the pounds you drop will be water weight, and some fat-burning muscle to boot. Without altering your lifestyle and eating habits, revisiting your relationship to food, and systematically enhancing the overall quality of the calories you consume, your diet is doomed to fail in the long run. In fact, research has shown that the vast majority of calorie-restricted diets fail long term. A study conducted at the University of California in Los Angeles showed that people who go on calorie-restricted diets typically lose 5 to 10 percent of their body weight within 6 months—but regain everything they’ve lost within 4 to 5 years. And this yo-yo effect causes downstream biological complications that make it even more difficult to lose weight in the long run.

Your body is a complex ecosystem, and all complex biological systems have mechanisms in place to maintain homeostasis. The dictionary defines homeostasis as “the maintenance of relatively stable internal physiological conditions (as body temperature or the pH of blood) in higher animals under fluctuating environmental conditions.” It’s easy to see why this is important. If you didn’t have a built-in biological mechanism for maintaining basic physiological processes such as body heat, survival would be far more complicated.

What does this have to do with weight? Well, the rate of your metabolism and the amount of fat you carry are tightly regulated by a complex array of homeostatic internal processes. Some doctors call this internal thermostat your “body weight set point,” and it’s influenced by a number of factors such as hormones, neurotransmitters, intestinal peptides, your gut microbiome, and more.

Several studies have shown that your body weight set point remains fairly constant, maintaining your body weight in a stable range despite minor changes in energy intake (calories in) and expenditure (calories out). It’s also been shown that your body is very efficient at holding on to weight during periods of caloric deprivation. That’s because your body set point has shifted downward and is telling your body that your metabolism needs to be slowed to minimize weight loss during periods of caloric deprivation. This provides a clear survival advantage but demonstrates how low-calorie diets that are based solely upon energy deprivation have short-term efficacy as the new set point limits ones weight loss. Your body weight set point will also try to keep you from gaining weight when you eat too much by burning more calories, but this effect is short lived.

Overall, it’s harder to lose weight than it is to gain weight—an experience many of us are all too familiar with. Yo-yo dieting is a very common result of weight-loss programs and causes one to ultimately weigh more. Yo-yo dieting has been shown to raise the body’s set point, which is your brain telling your body “Hey, we ought to now weigh more to reach this new equilibrium” and sending control signals throughout your body to slow metabolism so you gain body weight and fat mass—the new normal. Thus, you weigh more than before with each failed energy-deficit diet program and it becomes harder and harder to lose weight as the set point is raised each time a weight-loss regimen fails.

To effectively lose weight and keep it off, you need to strategically alter your body weight set point. Emerging evidence suggests that bariatric surgery, particularly gastric bypass, may work in part by helping the body establish a new set point by altering the physiology governing body weight.5 And that’s the real problem with yo-yo dieting— every time your weight rebounds, your set point gets pushed higher, so your body acclimates to the new body weight set point as “the new normal.” Hormonal and metabolic adaptations now make it more and more difficult to lose weight. Calories in/calories out doesn’t work for the masses, because it can’t work. It can’t work, because simply reducing the amount of food you consume and spending more energy exercising doesn’t necessarily influence your body weight set point. There are some people out there who can lose weight by eating less and jogging 100 miles a week, but they’re the exception. We may admire (or even be a little jealous of) them, but they don’t point the way for the majority of us to lose weight and stay healthy. So if eating less and exercising more isn’t a realistic, sustainable way to lose weight, what is?

Gerard E. Mullin MD is a board-certified internist, gastroenterologist and nutritionist. He is an associate professor of medicine and serves as the director of Integrative GI Nutrition Services at The Johns Hopkins Hospital. Dr. Mullin has accrued over 20 years of clinical experience in the fields of integrative gastroenterology and nutrition and he earned a master’s degree in nutrition while in practice in 1994.Dr. Mullin is regarded as an authority in integrative gastroenterology and was commissioned by Andrew Weil MD to edit Integrative Gastroenterology for his integrative medicine library for Oxford University Press. Dr. Mullin teaches medical professionals at international conferences on the role of nutrition and lifestyle and the gut microbiome in digestive health and weight control.He is the author of several books including his newest, The Gut Balance Revolution: Boost Your Metabolism, Restore Your Inner Ecology, and Lose the Weight for Good!

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