When we lose weight, we need to lose our fat and not our muscles. But few of us eat enough protein to succeed.
That's the conclusion of a study that The Journal of Nutrition just published. "A Moderate-Protein Diet Produces Sustained Weight Loss and Long-Term Changes in Body Composition and Blood Lipids in Obese Adults" appears in the journal's March 2009 issue. The abstract is online.
A team of nine researchers followed the weight-loss efforts of 130 people at the University of Illinois and Penn State University. Led by Professor Emeritus of Nutrition Donald K. Layman, Ph.D. of the University of Illinois department of food science and human nutrition, the researchers watched how well the participants in the study succeeded during four months of active weight loss and eight months of maintenance.
Half of the participants followed a moderate-protein diet consisting of 40 percent carbohydrates, 30 percent protein, and 30 percent fat. The other half followed a diet based on the U.S. Department of Agriculture's food-pyramid, which is 55 percent carbohydrate with the balance divided between protein and fat.
After four months the participants in the higher protein group had lost 22 percent more body fat than members of the food-pyramid group. And after a year those on the higher protein diet had lost 38 percent more body fat than those following the food pyramid.
"The additional protein helped dieters preserve muscle," Professor Layman says. "That's important for long-term weight loss, because muscle burns calories."
The higher protein diet was also easier to follow and maintain in the long-term. He says that 64 percent of those on the higher protein diet completed the study compared with 45 percent of dieters using the food-pyramid diet. "Subjects on the moderate-protein diet reported that they weren't as interested in snacks or desserts, and they didn't have food cravings," he said. "When you eat protein, you feel full longer."
But don't bother to read the highly technical research that Professor Layman and his colleagues reported in The Journal of Nutrition. Instead, you might want to listen to the much more interesting podcast interview that the journal did with him. This podcast is online.
Professor Layman made two salient points in that interview. He said that they we need 30 grams of protein per meal to maintain and protect skeletal muscles and to lose more body fat and less lean tissue. And then at the end of the interview he noted without elaboration that, "Breakfast is the key meal to making these diets actually work."
This is a whole lot of protein. It's far too much for many people with diabetes who have impaired kidney function. It's also a lot more than the established nutrition recommendations.
Adult men need 56 grams of good quality protein per day and most adult women need 46 grams, according to the Food and Nutrition Board of the Institute of Medicine. Pregnant women and nursing mothers need 71 grams.
My own diet has been closer to the recommendations of the Institute of Medicine. But now I plan to reduce the amount of fat in my diet to save room for more seafood, chicken, and steak.