Calorie Labels Are Dieting by Another Name

Obesity has surprisingly little to do with diet.

Posted Dec 05, 2014

If we measure calories of fast food, can we reduce the prevalence of obesity? No because the underlying cause of obesity has surprisingly little to do with diet. Helping people to eat less through food labeling is well intentioned but ignores the science of weight gain.

Labeling assumes that if people were to consume fewer calories, they would lose weight. That is true only if they embark on extreme dietary restriction that is dangerous to their health. A starvation regimen is very hard to stick to for the simple reason that humans are designed by natural selection to take in enough food to maintain their weight.

Diets do not work in the long run and people who try to restrict their food intake at unrealistic levels generally end up putting on more weight than they began with. This phenomenon of weight fluctuation followed by weight gain was illustrated by celebrity Oprah Winfrey.

When people and other mammals are food restricted, their bodies become remarkably efficient so that they retain more of the calories they consume. Moreover, the more cycles of dieting and relapse that they experience, the fatter they become.

We need to recognize that the pitfalls of dieting apply every bit as much to restaurants and fast food as to home-consumed meals. Calorie labeling will have minimal impact on menu choices and even less on obesity.

Starvation is not a good idea

Most of what goes for received wisdom about dieting is scientifically flawed, or plain wrong. The basic premise that obese modern populations got that way because they eat more than slimmer peoples do is wrong, and misleading. In fact, one can find indigenous people who eat about twice as much as we do (pound for pound) and have no obesity at all.

Examples range from the Ache hunter-gatherers of Paraguay to the Pima subsistence farmers of Mexico. Both eat a lot more than we do but have no obesity. Of course, the urban Pima of Arizona have one of the highest obesity rates in the world but follow a much more sedentary lifestyle.

Active people do not need to count calories

Active peoples, such as subsistence farmers, or hunter gatherers are lean and fit and do not suffer from obesity even though they eat far more than we do.

In the jargon of physiology, they defend a constant body weight. If they consume more energy than needed, their body generates more heat and blows it off. If they get too little food, their body conserves energy.

Because physically active populations maintain a constant body weight despite considerable variation in food intake, their precise calorie intake does not matter. Counting calories is therefore pointless for them.

It is important to be clear about what qualifies as “physically active.” Standard medical guidelines recommend about 2 ½ hours of vigorous physical activity per week. If we wanted to maintain a constant body weight after the manner of subsistence farmers or hunter gatherers, we would need to do this much exercise every day.

Do sedentary people need to count calories?

If a person is prepared to do the equivalent of walking briskly for two hours per day they will never suffer from overweight. What about the sedentary majority of Americans who are far less active than this? Would they benefit from counting calories if their inactivity leaves them more vulnerable to obesity?

The intention behind restaurant labeling of calories is that diners select menu items that contain fewer calories and thereby consume less. It also encourages restaurant chains to compete with lower-calorie entrees. But will this help Americans to lose weight? We all know that dieting doesn't work. Calling it by a different name “calorie labeling” is not going to make it work any better.

Nutrition does matter, of course, and energy-dense foods (e. g., ice cream, salami, potato chips, cheese, cookies) promote obesity, especially with snacking, whereas high-fiber foods (e. g., fruit, vegetables, whole grains) help prevent it. Yet, it is doubtful that a calorie count will induce anyone to substitute an apple for an ice cream, or lettuce for potato chips.

Sedentary populations are obese primarily because they get too little exercise not because they eat too much. So the new labeling laws resurrect old fallacies about dieting and obscure the severity of the inactivity epidemic.