The Power of Protein - Part 2: Protein & Body Composition
Sunday, July 12, 2009
LifeTime WeightLoss in Fat Loss, Nutrition, Protein, Tom Nikkola

The first post in this series looked at some of the misconceptions related to protein intake and its impact on health. The key message was that as long as someone is generally healthy, consuming protein beyond the Recommended Daily Allowance has not been shown to be detrimental to health. In some cases, such as bone metabolism, studies show that extra protein can actually be beneficial. Of course, consuming too much protein can lead to an excess of calories, which can increase body fat levels.

Protein & Body Composition

Many studies have shown a significant difference in weight loss success when consuming a higher amount of protein during a calorie-restricted diet. In fact, as caloric intake decreases, the requirement for protein increases.  From personal experience, clients who consistently ate or drank protein with each of their meals had an easier time controlling their calories and changing their body composition.

There are three ways increased protein may enhance body composition changes -- improved satiety, increased thermogenesis, and maintenance of lean body mass.

Improved Satiety

The most likely reason higher protein intake enhances weight loss is through improved satiety. Protein takes longer to digest than carbohydrate or fat. By ensuring each meal has a reasonable serving of protein, hunger may take longer to return. It may be that increased protein leads people to eat less overall calories because they are more satisfied from their meals. In addition, protein tends to reduce the glycemic effect of carbohydrates. If blood-sugar levels rise at a slower rate, they will also fall at a slower rate, which can lengthen the time before hunger returns. It may also reduce the cravings for more carbohydrates.

Increased Thermic Effect of Food

Another possible reason protein can aid in weight management is from increasing the total number of calories the body burns each day. The digestion of protein requires more work from the body than the digestion of carbohydrates of fat. The thermic effect of food refers to the calories the body must burn to digest the food we eat. Protein digestion can cause the body to burn 3-4 times as many calories during digestion as carbohydrates or fat, calories being equal. One study showed a higher-protein diet can result in an extra 90 or more calories burned each day. Burning an extra 90 calories per day may not seem significant compared to an average 2000-calorie diet, but every extra calorie helps in the goal of decreased body fat levels. Theoretically, burning an extra 90 calories per day could be a 9-pound difference in body fat over the course of a year.

Maintenance of Lean Body Mass

The third way protein may enhance body composition is through the maintenance of lean body mass. As people lose weight, it is common to lose lean body mass (muscle and bone). It's not possible to prevent all losses of lean body mass for those who have higher amounts of weight to lose, but additional protein intake can help individuals maintain optimal levels of lean body mass. Those who focus on calories alone, and neglect sufficient protein intake, can find themselves at a lower body weight, but with higher body fat percentages. In the end, when people are looking to "tone-up" or "get more defined," it is critical to eat enough protein.

Summary

Adding more eggs, chicken, soy, whey, or other protein to a nutrition plan may not sound as exciting as the latest weight-loss pill or ingredient of the month. However, looking at ones actual diet, and replacing some of the calories from fat or carbohydrate with protein can have much more of an effect in changing body composition than anything else.

Go to: Part 1 - Protein and Health Concerns

Go to: Part 3 - Recommended Intake and Protein Sources

Written by Tom Nikkola - Director of Nutrition & Weight Management

References:

Layman DK, Evans E, Baum JI, Erickson DJ, Boileau RA. Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women. J. Nutr. 135: 1903–1910, 2005.

Westerterp-Plantenga MS, Rolland V, Wilson SA, Westerterp KR.Satiety related to 24 h diet-induced thermogenesis during high protein/carbohydrate vs high fat diets measured in a respiration chamber. Eur J Clin Nutr. 1999;53:495–50

Lowery LM, Devia L. Dietary protein safety and resistance exercise: what do we really know? J of the Int Soc Spo Nut. 2009, 6:3

Clifton PM, Keogh JB, Noakes M. Long-term effects of a high-protein weight-loss diet. Am J Clin Nutr. 2008; 87:23-9

Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. Am J Clin Nutr. 2006; 83:260-74

Layman DK, Evans EM, Erickson D, Seyler J, Weber J, Bagshaw D, Griel A, Psota T, Kris-Etherton P. A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults. J Nutr. 2009 139: 514-21

Article originally appeared on LifeTime WeightLoss (http://www.lifetime-weightloss.com/).
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