Can a High-Protein Diet Help You Lose Weight?
Eight ways to pump up the protein in your diet

By Kathleen Zelman, MPH, RD/LD
WebMD Weight Loss Clinic, Jan. 2006

Low-carb diets are last year's news, but high-protein is emerging as the latest buzz in weight control. That's because emerging research has hinted that protein may be able to satisfy hunger better than either fats or carbohydrates.

Could a high-protein diet really help you eat fewer calories (and thus lose weight) by keeping your hand out of the cookie jar? WebMD asked some experts for their views.

8 Ways to Pump Up the Protein

If you'd like to start including more lean protein in your daily diet, Tallmadge offers these eight simple tips:

What Studies Show

Participants in a study recently published in the American Journal of Clinical Nutrition reported greater satisfaction, less hunger, and weight loss when fat was reduced to 20% of the total calories in their diets, protein was increased to 30%, and carbs accounted for 50%. The study participants ate some 441 fewer calories a day when they followed this high-protein diet and regulated their own calorie intake.

Another study, reported in the Journal of Nutrition, showed that a high-protein diet combined with exercise enhanced weight and fat loss and improved blood fat (lipid) levels.

"Our research suggests that higher-protein diets help people better control their appetites and calorie intake," says researcher Donald Layman, PhD, a professor at the University of Illinois at Urbana-Champaign.

"Diets higher in protein [and] moderate in carbs, along with a lifestyle of regular exercise have an excellent potential to reduce blood lipids [and] maintain lean tissue while burning fat for fuel without dieters being sidetracked with constant hunger."

Researchers don't understand exactly how protein works to turn down appetite. They surmise that it may be because a high-protein diet causes the brain to receive lower levels of appetite-stimulating hormones.

"We are not exactly sure of the mechanism for satiety, whether it is due to [eating] fewer carbs and/or the specific protein effect on hunger hormones and brain chemistry," Layman says.

And more research is needed before experts can make sweeping recommendations that people boost the protein in their diets, says American Dietetic Association president Rebecca Reeves, DrPH, RD, an obesity researcher at the Baylor College of Medicine.

"I think it is fascinating and intriguing, yet we need the evidence that higher-protein diets are more effective over the long term," Reeves says.

How Much Do You Need?

We need protein at all stages of life, for a variety of bodily functions. It's the major component of all cells, including muscle and bone. It's needed for growth, development, and immunity to fight off infections and protect the body.

The Institute of Health's Dietary Reference Intake (DRI) recommendations allow for a wide range of protein intake -- anywhere from 10% to 35% of total calories -- for normal, healthy adults. For example, on an 1,800 calorie diet, you could safely consume anywhere from 45 grams (that's 10% of calories) to 218 grams (35%) of protein per day.

However, the Recommended Dietary Allowance (RDA) for protein is 56 grams a day for men and 46 grams a day for women. Most Americans have no problem getting this much, but would struggle to take in enough protein to make up 35% of their calories.

That said, is it possible to eat too much protein?

"There are no dangers associated with higher intakes of protein -- unless you have kidney disease," says Layman.

To get the potential weight loss benefit, Layman advises aiming for around 120 grams of protein a day. "If you want to increase your protein intake, do it slowly over the course of a week," he recommends.

To be on the safe side, check with your doctor before adding large amounts of protein to your diet.

Controlling Your Appetite

In theory, losing weight is quite simple -- just eat less and exercise more -- but of course, putting it into practice can be complicated. Finding a diet with the right combination of nutrients, that you enjoy, and works with your lifestyle is a very individual process.

"Some people fare better on a high-carbohydrate, diet whereas others are hungry all the time on the same diet," Layman says.

And of course, if you're hungry all the time, eating fewer calories will be challenging.

For better appetite control, Reeves recommends dividing your daily calories into smaller meals or snacks and enjoying as many of them as possible early in the day, with dinner being the last meal.

"People who eat four to five meals or snacks per day are better able to control their appetite and weight, according to the scientific literature," says Reeves.

And as long as you stay within the recommended limits, Reeves says, you can try adding some protein to your diet.

"If the DRIs give us permission to push up the protein," she asks, "what is the harm in adding some lean protein or low-fat dairy to your diet -- unless you have a condition that would limit protein?"

The Best Protein Sources

Protein is important but so are carbohydrates, fats, and total calories, says Katherine Tallmadge, MA, RD, a spokeswoman for the American Dietetic Association.

"It is all about balance," says Tallmadge, author of Diet Simple. While she recommends including lean and low-fat sources of protein at every meal, she says it should be part of a calorie-controlled diet that's also rich in 'smart carbs' such as fruits, vegetables, and whole grains, along with healthy fats like nuts, seeds, olives, oils, fish, and avocado.

She also notes that not all protein is created equal. Be sure to look for protein sources that are nutrient-rich and lower in fat and calories, such as lean meats, beans, soy, and low-fat dairy, she says.

Here are some good sources of protein, as listed by the U.S. Department of Agriculture:

Food (watch fat content also - WST) Protein grams
1 ounce meat, fish, poultry 7
1 large egg 6
4 ounces milk 4
4 ounces low-fat yogurt 6
4 ounces soy milk 5
3 ounces tofu, firm 13
1 ounce cheese 7
1/2 cup low-fat cottage cheese 14
1/2 cup cooked kidney beans 7
1/2 cup lentils 9
1 ounce nuts 7
2 tablespoons peanut butter 8
1/2 cup vegetables 2
1 slice bread 2
1/2 cup of most grains/pastas 2

Published January 2006.

SOURCES: Journal of Nutrition, July 2005. American Journal of Clinical Nutrition 2005; 82:41-8. Lancet 2004; 364:897-9. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fatty Acids, Cholesterol, Protein and Amino Acids, Institute of Medicine, September 2002. USDA Nutrient database release 18, January 2005. Donald Layman, PhD, professor, University of Illinois at Urbana-Champaign. Rebecca Reeves, DrPH, RD, assistant professor, Behavioral Medicine Research Center, Baylor College of Medicine; president, American Dietetic Association. Katherine Tallmadge, MA, RD, spokesperson, American Dietetic Association; author, Diet Simple.

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