Calorie reduction — not carbs, protein or fat — key to weight loss, study says

Should you try to lose weight with a low-fat diet? A high-protein diet?

Or is avoiding carbs the answer?

Well, according to a new study in this week’s issue of the New England Journal of Medicine, it doesn’t seem matter—as long as you cut calories.

In the study, 811 overweight men and women were randomly divided into four diet groups.

• One group was assigned a low-fat, average protein group, which got 65 percent of their calories from carbohydrates.  
• The second group was assigned a low-fat, high-protein diet with 55 percent of calories from carbohydrates.
• The third group was assigned a high-fat, average protein diet with 45 percent of calories from carbohydrates.
• And the fourth group was assigned a high-fat, high-protein diet with 35 percent of calories coming from carbohydrates.

All the diets, however, were “heart-healthy”, meaning they were low in saturated fats (such as butter and animal fat) and high in whole cereal grains, fruits and vegetables—all good sources of fiber.

To lose weight, each participant were encouraged to reduce their intake of overall calories by 750 calories a day, though not lower than 1,200 total calories a day.

Participants were also asked to do 90 minutes of moderate exercise a week.

At the end of two years, the results were similar in all four groups.

On average, participants lost 13 pounds after being on the diets for six months and, though they slipped a little, had maintained a 9-pound weight loss at two years and lost two inches off their waistlines.

Most risk factors for heart disease, such as high blood pressure, elevated LDL Cholesterol (the “bad” cholesterol) and triglycerides, improved in all four diet groups.

The findings, says the study’s lead investigator Dr. Frank Sacks of the Harvard School of Public Health, indicates that weight-loss efforts should focus “on reducing calorie intake rather than any particular proportions of fat, protein or carbohydrate.”

But in an editorial commenting on the paper, Martijn B. Katan, Ph.D. of the Institute of Health Sciences, VU University, Amsterdam, noted that the study was longer than many and included intensive counseling and still many participants did not stick to their diets and and many regained what weight they had lost. 

And Professor Katan points out,”the weight regain during the second year, although slow, suggests that in the end many participants might have regained their original weight even if treatment had continued.”

The study was conducted by researchers from the Harvard School of Public Health and the Pennington Biomedical Research Center at the Louisiana State University System and funded by the National Heart, Lung, and Blood Institute.

To learn more:

• Read the article and the editorial, which are available for free on the New England Journal of Medicine’s Web site.
• For information about the weight control and the risks of being overweight go to the National Heart, Lung, and Blood Insitute’s information page.
• Visit the Institute’s Aim for a Healthy Weight Web page, which includes a body mass index calculator, menu planner and other online tools to help you achieve a healthy weight.
• Read Dr. Carolyn Clancy’s article on tips for losing weight in LocalHealthGuide

Local resources where you can find information about diet and fitness:

• Washington State Department of Health: Physical Activity & Nutrition information page
• Partners in Action: Nutrition and Physical Activity in Washington
• Washington Coalition for Promoting Physical Activity
• Public Health-Seattle & King County site for physical activity
• King County Overweight Prevention Initiative

Tags: Diet, Dieting, Fitness, Obesity, Weight Loss

Category: Fitness & Exercise