Looking for weight loss that lasts long after January’s get-back-in-shape season? For keeping pounds off, low-fat dieting works better than low-carb dieting, says new research.

The study, presented at the North American Association for the Study of Obesity in Las Vegas in November 2004, involved 2,700 men and women, all part of the National Weight Control Registry. The Registry, launched more than 10 years ago by scientists at the University of Colorado and the University of Pittsburgh, encourages people to join who have lost at least 30 pounds and kept them off for at least one year. To date, the Registry has gathered more than 4,000 members. Scientists are now mining the data, isolating members’ secrets for long-term weight loss success.

In this latest research, psychologist Susanne Phelan of Brown University Medical School analyzed the diets of the 2,700 people who entered the Registry from 1995 to 2003.  Initially, they had lost on average 72 pounds. Dr. Phelan found that the ones who had regained the most weight in the year after their initial weight loss were those who had increased their fat intake and decreased their carb intake.

Those who continued to follow a low-fat diet high in carbohydrates were most successful at keeping the pounds from creeping back.

Phelan’s conclusions:  Only a minority of successful weight losers consumes a low-carb diet.  A low-fat diet rich in healthy, high-fiber carbohydrates continues to be the key characteristic of long-term success.

Eat More, Weigh Less

In related research, also presented at the North American Association for the Study of Obesity, scientists at Pennsylvania State University found that to lose weight, we need to eat more water-rich, fiber-rich foods like fruits and vegetables – and fewer foods that are dense with calories, like oils and cheese.

In the study, Dr. Julie Ello-Martin divided 101 obese women into two groups. She directed the first group to fill up – eat as much as they wanted – of foods that were low in calorie density, such as fruits and vegetables, and to choose fat-reduced foods over full-fat foods. The second group got stricter guidelines: cut both portion sizes and fat grams.

After six months, the first group lost an average of 21 pounds; the second group, only 15 pounds. The study showed, reported Dr. Ello-Martin, that you can lose significant weight without needing to count calories or eat less-than-satisfying portions – and, best of all, the diet you’re following is very healthful.