April 7, 2000 (New York) -- We all know someone who's on one, been on one, or swears by a trendy diet that proclaims the key to weight loss is not eating certain foods together.
Whether you're talking about a "combination diet" such as the "Fit for Life" diet plan that says you should never combine fruits and other carbohydrates with proteins, or the "Carbohydrates Addict" diet that says you can only eat carbs for one hour each day, the first clinical study of combination diets shows that these diets -- and others like them -- are no better or worse than traditional balanced diets.
Confirming what many nutritionists and weight loss experts have been saying for years, it's the calories -- not the food combinations --that count, the study shows.
Reporting their findings in the April issue of the International Journal of Obesity, Alain Golay, MD, of the University of Geneva in Switzerland, and colleagues report that obese adults lost about the same amount of weight whether they were on a food combo diet or a traditional balanced diet.
All 54 study participants were put on a 1,100 calorie-per-day diet for six weeks. Half of the participants consumed the diet normally, while the other half ate fat and carbohydrates separately. For example, a typical lunch for participants on the balanced diet included low-fat meat or fish, vegetables, rice, pasta or cereal, fruit, and oil. A typical lunch for a participant on the combined diet included low-fat meat or fish, vegetables, low-fat fresh cheese, and oil. Both diets contained similar amounts of fat, and cholesterol and calories were distributed between breakfast, lunch, dinner, and a bedtime snack.
The people on the balanced diet lost an average of 16.5 pounds, while those on the food-combining diet lost an average of 13.6 pounds. Participants in both groups showed identical decreases in body fat, blood sugar levels, cholesterol, blood fats, and insulin. High levels of blood sugar, insulin, cholesterol, and blood fats increase risk for heart disease and diabetes.
The bottom line, according to Arthur Frank, MD, medical director of the George Washington University Weight Management Program in Washington, is that "you can't eat more to weigh less -- it's the calories that count."
"The new study goes a long way toward dealing with diets like the Atkins diet," he tells WebMD. The Atkins diet is an exclusion diet, not a combination diet. It allows people to eat as much protein and fat as they like, as long as they consume few carbohydrates.
"All of these fad diets reduce caloric intake. They don't tell you that, though. Instead, they just promote their gimmicks," says Ruth Kava, PhD, RD, director of nutrition for the American Council on Science and Health, a nonprofit consumer education group in New York City. "My advice is to pay attention to the caloric content of foods, and if you want to eat your bread and fruit separately, it doesn't matter as long as you are getting some of each."
But the biggest question, she says, is whether people will be able to stick to the various restrictions of fad diets, "because the hardest thing to do is keep weight off after losing it."
- When researchers gave their study subjects a 1,100 calorie-per-day diet, it didn't matter if the subjects ate a regular balanced diet or consumed fats and carbohydrates separately. Both groups lost about the same amount of weight and body fat, lowered their blood sugar levels equally, and had the same reduction in blood fats and insulin levels.
- Observers note this study emphasizes that calories are the important factor to losing weight.
- They also note many fad diets bring initial success because they make followers eat less. But the real test is how long people can follow any eating regimen in order to avoid regaining body weight.