A landmark study just came out of the Harvard School of Public Health and the NIH.
Researchers recruited 811 overweight or obese older adults and put them on one of four diet plans. Two of the plans were low-fat plans with 20% of calories from fat. Two of the plans were high-fat plans with 40% of calories from fat. The calories from carbohydrates ranged from 35% to 65%. Protein was either 15% or 25% of calories.
All four plans adhered to heart-healthy guidelines, which emphasize eating less than 8% of calories from artery-clogging saturated (animal) fat, eating vegetables, fruits and whole-grain products, and consuming at least 20 grams of fiber a day.
The eating plans were based on the DASH (Dietary Approaches to Stop Hypertension) diet, not on popular plans such as the Atkins or South Beach diets.
Dieters were encouraged to attend regular individual and group weight-loss counseling sessions and keep an online food diary. Everyone was given a personalized calorie goal, and most aimed for 750 calories below their daily needs. No one was supposed to eat fewer than 1,200 calories a day.
Participants' exercise goals were modest: about 90 minutes of moderate physical activity a week. Researchers were focused on how the composition of the diets affected weight loss and did not want to distort the results.
Among the findings, presented in today's New England Journal of Medicine:
• In six months, the dieters lost an average of 13 pounds no matter which diet they were on.
• After two years, they had kept off an average of 9 pounds and lost 1 to 3 inches in the waist, regardless of which diet they were on.
• Dieters had improvements in heart-disease risk factors, including increases in the HDL (good) cholesterol, and decreases in LDL (bad) cholesterol and triglycerides (blood fats) at six months and two years.
• People reported similar levels of fullness, hunger and satisfaction on the different diets.
'Reasonable range' of fats, protein, carbs
The plans did not include a very low-carb Atkins-type diet, Sacks says, because most "people don't stick with that low-carbohydrate intake, and we didn't want to try anything unrealistic. We tried a big range but a reasonable range of fats, protein and carbohydrates."
Some research indicates that dieters may feel full longer on higher-protein diets, but these dieters did not report any differences in feelings of fullness, says Catherine Loria, a nutritional epidemiologist with the heart, lung and blood institute.
THE BOTTOM LINE:They came up with "a very simple message that cuts through all the hype: To lose weight, it comes down to how much you put in your mouth — it's not a question of eating a particular type of diet," says Frank Sacks, a lead researcher and professor of cardiovascular disease prevention at Harvard.
* Information obtained from the New England Journal of Medicine and USA Today
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