18 May Always Hungry? Here’s Why – Op-ed from NYTimes
“What if we’ve confused cause and effect? What if it’s not overeating that causes us to get fat, but the process of getting fatter that causes us to overeat?” asks David S. Ludwig in Opinion.
These ideas aren’t entirely new. The notion that we overeat because we’re getting fat has been around for at least a century, as described by Gary Taubes in his book “Good Calories, Bad Calories.” In 1908, for example, a German internist named Gustav von Bergmann dismissed the energy-balance view of obesity, and hypothesized that it was instead caused by a metabolic disorder that he called “lipophilia,” or “love of fat.”
But such theories have been generally ignored, perhaps because they challenge entrenched cultural attitudes. The popular emphasis on calorie balance reinforces the belief that we have conscious control over our weight, and that obesity represents a personal failure because of ignorance or inadequate willpower.
In addition, the food industry — which makes enormous profits from highly processed products derived from corn, wheat and rice — invokes calorie balance as its first line of defense. If all calories are the same, then there are no bad foods, and sugary beverages, junk foods and the like are fine in moderation. It’s simply a question of portion control. The fact that this rarely works is taken as evidence that obese people lack willpower, not that the idea itself might be wrong.
UNFORTUNATELY, existing research cannot provide a definitive test of our hypothesis. Several prominent clinical trials reported no difference in weight loss when comparing diets purportedly differing in protein, carbohydrate and fat. However, these trials had major limitations; at the end, subjects reported that they had not met the targets for complying with the prescribed diets. We wouldn’t discard a potentially lifesaving cancer treatment based on negative findings, if the research subjects didn’t take the drug as intended.
There are better ways to do this research. Studies should provide participants with at least some of their food, to make it easier for them to stick to the diets. Two studies that did this — one by the Direct Group in 2008 and the other by the Diogenes Project in 2010 — reported substantial benefits associated with the reduction of rapidly digestible carbohydrate compared with conventional diets. We need to invest much more in this research. With the annual economic burden of diabetes — just one obesity-related complication — predicted to approach half a trillion dollars by 2020, a few billion dollars for state-of-the-art nutrition research would make a good investment.
If this hypothesis turns out to be correct, it will have immediate implications for public health. It would mean that the decades-long focus on calorie restriction was destined to fail for most people. Information about calorie content would remain relevant, not as a strategy for weight loss, but rather to help people avoid eating too much highly processed food loaded with rapidly digesting carbohydrates. But obesity treatment would more appropriately focus on diet quality rather than calorie quantity.
People in the modern food environment seem to have greater control over what they eat than how much. With reduced consumption of refined grains, concentrated sugar and potato products and a few other sensible lifestyle choices, our internal body weight control system should be able to do the rest. Eventually, we could bring the body weight set point back to pre-epidemic levels. Addressing the underlying biological drive to overeat may make for a far more practical and effective solution to obesity than counting calories.
David S. Ludwig directs the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital and is a professor of pediatrics at Harvard Medical School. Mark I. Friedman is vice president of research at the Nutrition Science Initiative.