According to a new study if you want to lose weight it doesn't matter which diet you choose but what matters is how much or little you eat.

Researchers to try and find the perfect diet for weight loss put people on different diets which had varying degrees of fat, proteins and carbohydrates and found that all diet plans were as effective as long as you watched the quantities of food that you consumed. Study author Dr. Frank Sacks, a professor of cardiovascular disease prevention at the Harvard School of Public Health said, the study had "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,"

A two-year study of 811 overweight people, 40 % of them men was financed by the National Heart, Lung, and Blood Institute of the National Institutes of Health. The study was conducted by experts at the Harvard School of Public Health in Boston and the Pennington Biomedical Research Center in Baton Rouge, part of the Louisiana State University system.

They divided the people into four groups and assigned each group one of four diet plans which were based on the DASH (Dietary Approaches to Stop Hypertension) diet. All four plans complied with the heart healthy guidelines, which recommend consuming 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 four diets were randomly assigned and the first was a low-fat, average-protein diet made up of 20 percent fat, 15 percent protein and 65 percent carbohydrates. The second diet was a low-fat, high-protein diet of 20 percent fat, 25 percent protein and 55 percent carbohydrates while the third was a high-fat, average-protein plan containing 40 percent fat, 15 percent protein and 45 percent carbohydrates. The fourth diet was a high-fat, high-protein diet of 40 percent fat, 25 percent protein and 35 percent carbohydrates.

All four groups were given a physical activity goal of 90 minutes a week and each person received a personalized calorie goal, and most aimed for 750 calories below their daily needs and no one was supposed to eat fewer than 1,200 calories a day.

Each person received individual as well as group counseling for the two year period of the study and had to maintain a record of their diet and exercise information into a computer program that provided feedback on how well they were meeting their dietary goals. About 80 % of the participants completed the study.

The researchers reported that at the end of six months, the dieters lost an average of 13 pounds no matter which diet they were on and 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.

Regardless of which diet they were on the dieters showed 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.

Irrespective of the diet all the participants reported similar levels of fullness, hunger and satisfaction on the different diets.

Sacks said, "This study has a very practical, useful message. It doesn't really matter much the specific type of diet -- see what suits you best. The focus should be on reducing calories. That's what really counts."

He concluded by saying, "On average, no one diet was better than another." If you want to lose weight, he said, "Eat a heart-healthy diet and be very careful about how much you eat."

The study is published in the Feb. 26 issue of the New England Journal of Medicine