Does this mean that low-carb diets are better than low-fat diets?
There's probably no perfect diet that's going to fit everyone. But from our study, you could say if someone was to lose 20 lbs., you might be better off having done it on the low-carbohydrate diet. Your triglyceride levels would be lower, you wouldn't have lost any HDL, and if you were diabetic, you would have improved your blood-sugar levels. You can lose weight more quickly, too. At six months, our low-carb group lost a little less than 13 lbs., while the low-fat group lost a little bit more than 4 lbs. By the end of the year the low-carb group lost about 12 and the low-fat group lost about 8. The low-carb group still lost more weight, but it was statistically equivalent at that point.
Does the low-carb diet work so well because people are eating less?
I think that's part of it. There are cultures in the world who eat more fat and protein, but they don't eat more carbohydrates with it. A problem with our American diet is we eat too much of everything. People need to stop eating when they start to feel full.
Is going low-carb safe?
We only have data for a year. In the short term, it certainly appears to be safe. More research needs to be done for the longer term.
Should some people avoid a low-carb diet?
People with poor kidney function should be cautious. People with severe kidney or liver disease should consult their doctors.
Why do some people find it easier to stay on a low-carb diet?
It might be that protein and fat make people feel more satisfied. Or it might be that a high-carb diet, which tends to cause great flux in insulin levels, makes people feel more hungry.
Does it come down to what we've all heard before: Calories count?
I think you can do well on either diet. There might be some advantages on the low-carbohydrate diet, but the bottom line is calories count. For many people going on a low-carbohydrate diet, that means cutting out soda, french fries, doughnuts, 4-OZ. bagels. When the message was eat low-fat, Americans interpreted that to mean they could eat unlimited quantities of [fat-free] carbohydrates. My fear is that cutting out carbs will be interpreted to mean you can eat unlimited quantities of fat and meat. The bottom line is, to lose weight we need to eat less food.
Sure, the world has gone nuts for low-Carb diets. Everyone with a few—or 50—pounds to lose is turning to some variation of Atkins, South Beach or the Zone. But some doctors have never been convinced that low-carb regimes work as well—or are as healthy—as low-fat diets. A study just published in the Annals of Internal Medicine may change their minds. It tracked 132 obese people—half of them went low-carb, half went low-fat—for one year. The groups lost roughly the same amount of weight, but the low-carb dieters dropped the pounds more quickly. Perhaps more surprisingly, the low-carb regime turned out to be better for heart health: At the end of the study, the carb group had lower levels of triglycerides (blood fats that are a risk factor for heart disease), while those on the low-fat plan had lower levels of HDL ("good cholesterol," which protects the heart). PEOPLE correspondent Sharon Cotliar spoke with the study's lead author, Dr. Linda Stern, an internist at the Philadelphia V.A. Medical Center, who launched her research after testing out the diet for her patients.