Curbing carbohydrates, not calories

This month, a long-delayed regulation came into effect requiring all food chains with 20 or more locations to list calorie information on their menus. Nutritionists fought to include the rule in the Affordable Care Act as a means of fighting obesity. But it turns out the regulation is based on weak science.

Until now, only a handful of cities mandated calorie counts in restaurants. In New York City, which pioneered the policy in 2008, menu labeling has had no effect on how many calories diners consume, according to a large study by New York University. Before the Food and Drug Administration’s rule was enacted, the U.S. Department of Health and Human Services commissioned a rigorous controlled experiment from the Rand Corp. The results, published this year, found that if people were informed about the calories in menu items, they purchased food with 38 fewer calories on average. That’s the equivalent of about three walnuts.

The justification from the start, as articulated in a blog post by FDA Commissioner Scott Gottlieb, is that saving even a few dozen calories a day would add up over the course of a year. “Based on that sort of reduction,” he wrote, “you could end up consuming 10,000 to 20,000 fewer calories, making you three to five pounds slimmer.”

Although we’ve long held on to the idea that slimming down is a matter of beating the math—create a caloric deficit of 3,600 calories and lose a pound of fat—the evidence has been stacking up against it for more than a century.

Since the early 1900s, medical research has shown that people do lose weight on calorie-restricted diets in the short term. But in most cases, they quickly gain it back. Moreover, the researchers found, people usually put back on more weight than they’d lost. This cruel twist is due to the fact that a person’s metabolic rate slows down to accommodate semi-starvation, but it doesn’t bounce back, resulting in a stubbornly depressed metabolism. To maintain that weight loss, it appears a person must restrict calories for life—a state of deprivation that, as it turns out, few humans can sustain.

Yet we seem committed to the myth that weight loss is merely a matter of calories in vs. calories out. That’s why it’s front-page news when researchers discovered that most participants in The Biggest Loser reality TV show didn’t maintain their new low weight, and that six years out, several weighed more than when they appeared on the show.

Thankfully, new avenues of research offer hope, as scientists discover factors other than calories that affect how our bodies regulate weight.

Insufficient sleep may impair fat loss, as one small controlled trial concluded. Not getting enough sleep increases the hunger hormone, ghrelin, according to another study. Chronic stress appears to stimulate ghrelin as well as the stress hormone cortisol, which is thought to weaken the body’s ability to metabolize carbohydrates.

The most promising area of obesity research focuses on the effects of eating carbohydrates. Some 70 clinical trials show that restricting carbohydrates is a highly effective way of fighting obesity. Low-carbohydrate diets are either equally or more effective than low-calorie diets, according to an analysis in the Journal of the American Medical Association.

One of the reasons low-carb diets work is precisely that they don’t require counting calories. People are allowed to eat as much as they like, so long as they keep carbohydrates low. In part because foods with protein are satiating, people on this diet don’t get hungry. Their metabolism doesn’t slow down, and they aren’t required to sustain a state of semi-starvation.

Counting calories doesn’t work, and it distracts us from what does work. Based on the most up-to-date science, this means curbing carbs instead of counting calories, and getting a good night’s sleep. It’s a shame the government is requiring restaurants to bear the burden of a policy that is sure to fail.

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