Monday, November 19, 2018
 Supplemental Whey Protein Helps Preserve Muscle in Older Women on a Calorie-restricted Diet  

Obese older women with decreased muscle mass and strength are at an increased risk of physical disability. A higher protein, calorie-restricted diet supplemented with whey protein showed a greater maintenance of muscle relative to weight loss compared with a diet higher in carbohydrates and lower in protein in a six-month, double-blind, randomized clinical trial in 26 overweight or obese older women (average age 65 years). The higher vs. lower protein group also showed a trend toward greater weight loss (8 vs. 4 percent body weight).

Meal plans were designed to decrease daily energy intake by approximately 500 calories/day, with a goal of 10 percent weight loss over six months. Participants were randomly assigned to receive a protein supplement (50 grams/day of whey protein isolate) or a carbohydrate supplement (50 g/day maltodextrin). The higher-protein diet provided approximately 30 percent of calories from protein, 40 percent of calories from carbohydrate and 30 percent of calories from fat; the higher-carbohydrate diet provided approximately 18 percent of calories from protein, 52 percent of calories from carbohydrate and 30 percent of calories from fat. Dual-energy x-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) were used to measure muscle and fat changes during the intervention.

There were no differences in strength, balance or physical performance between the protein and carbohydrate groups. However, when data from groups were combined, strength decreased, but balance and physical performance improved from baseline for all subjects. The authors said in order to see a significant effect on physical function, some aspects of the study design may have needed to change, such as having a bigger sample size, providing more whey protein, inducing a greater weight change, using more sensitive performance measures or investigating a population with compromised physical function.

The authors said the improved maintenance of muscle seen in this population indicates that a higher-protein intake can be important during weight loss. This whey protein supplementation study adds to the published literature on the benefits of a higher-protein diet on body composition during weight loss. The study also provides excellent preliminary data for future clinical trials to determine the most beneficial combination of a higher protein diet, weight loss and exercise to improve body composition and physical function in older women.

Authors: Mojtahedi MC, Thorpe MP, Karampinos DC, Johnson CL, Layman DK, Georgiadis JG, Evans EM.

Source: Dairy Research Institute

Posted on Thursday, September 29, 2011 (Archive on Thursday, October 06, 2011)
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