Louis Aronne, MD
Louis Aronne, MD, professor of medicine, Weill Cornell Medical College, director, Comprehensive Weight Control Center at Weill Cornell Medicine and New York-Presbyterian, both in New York City.
There are many popular ways to lose weight. Lots of people try cutting calories across the board, but then they are hungry a lot of the time. Others dramatically cut carbs, which often helps with hunger, but that is hard to stick with if you love “carb-y” foods. Some people practice intermittent fasting, eating only 500 or 600 calories on certain days, but you might find that overly restrictive, too.
Fortunately, there is another, little-known approach that’s just as effective as any of the above—and a whole lot easier for many people to stick with. Like intermittent fasting, it involves restrictive days, and like low-carb dieting, it involves drastically cutting carbohydrates. But here’s the big difference: All you do is go low-carb twice a week, without counting calories at all. The rest of the week you eat as much of a normal healthy diet as you want. It may work by “resetting” the brain so that you’re not as hungry—not just on low-carb days but even when you go back to your “normal” way of eating the rest of the week.
Here’s how to make it work for you.
At the Comprehensive Weight Control Center at Weill Cornell Medical College, we became interested in this new approach when we reviewed a four-month British study of 115 overweight women. The women were divided into three groups…
Results: The two-day-a-week low-carb dieters lost just as much weight as the intermittent fasters…and lost more weight than the everyday dieters. And besides losing more weight (11 versus eight pounds), the two-day-a-weekers also lost more body fat, becoming lighter and leaner.
What was even more intriguing was that just cutting carbs on those two days—and not counting overall calories—was as effective as intermittent fasting. In fact, neither group tended to overeat on days when they weren’t, respectively, cutting carbs or fasting.
Could it really be that easy to lose weight—just cut carbs two days a week? Yes, it could—because carbs do some very particular things to the brain.
When you eat a lot of carbohydrates, especially simple starches and sugars, it can literally damage neurons in the hypothalamus, a part of the brain that helps regulate appetite. The nerve cells in the hypothalamus become surrounded by inflammatory cells, and then they don’t function as well as they should.
Quality of fat matters, too. In animal studies, for example, high-saturated-fat diets—the kind of fats that are very prevalent in a typical Western diet—have also been shown to disrupt the appetite-signaling pathways. So the emphasis on healthy, mostly unsaturated fats in the diet may contribute to its effectiveness.
In effect, the brain becomes resistant to input from hormones, including leptin and ghrelin, which play key roles in regulating appetite. The hypothalamus mistakenly sends out signals to eat more. You feel hungrier, you eat more, and you create more damage—and so on.
The secret of the two-day-a-week carb-cutting diet is that the hunger-signaling pathway can be “reset” by giving the damaged neurons a break by cutting carbs, which also tends to cut calories, and by your eating healthy polyunsaturated and monounsaturated fats. When the oxidative load that’s hitting those nerves decreases, the whole system can work much better.
That explains why people on this diet don’t go crazy with overeating on their “off diet” days. Even after just one day of going very low carbohydrate, the signaling system between the appetite hormones and the hypothalamus works much more efficiently. That effect can last for a few days.
In our clinical experience, we have found that there is no need to avoid carbohydrates two days in a row. We tell dieters that they are free to restrict their carbohydrates on any two days of the week.
For a lot of people, just eliminating bread, pasta and sweets (sugars are carbs) gets most of the job done. But for a little more detail, here’s a sample one-day low-carb menu…
True, there’s no linguine with clam sauce…no bread-and-jam. But it’s only for a few days a week—and on the other five days, you may find that you’re not craving carbs as much as you do now. You’re almost sure to lose weight.