Aging is associated with a decrease in lean muscle mass. Weight loss by caloric restriction results in reduced fat mass and lean mass in middle-aged adults. But, it has been unclear as to the impact of weight loss on the muscle mass of older adults. This has led to the reluctance of health professionals to advise weight loss for this group despite the increased prevalence of overweight and obesity. For example, data for measured adult body mass index, from the 2004 Canadian Community Health Survey, indicate that about 2/3rds of women aged 55 to 74 years would classify as overweight and obese.
A recent study, published in the Journal of the American Dietetic Association (July 2008), looked at the impact of weight loss on the lean muscle mass of 70 overweight and obese postmenopausal women aged 50 to 70 years. The protein content of the diet for the three study groups (diet only, diet + low intensity aerobic exercise and diet + high intensity aerobic exercise) was 15 to 20% of calories, which equated to 0.47 to 0.8 g/kg body weight/day (average 0.62 g/kg body weight/day). The Acceptable Macronutrient Distribution Range (AMDR) and RDA for protein for this age group are 10 – 35% of total calories and 0.8 g/kg body weight/day, respectively.
Average weight loss and relative reduction in lean mass (33%) were similar between the intervention groups. However, those with higher dietary protein intakes lost more fat mass and less lean mass. The authors stated “for every 0.1 g/kg body weight/day increase in dietary protein, participants lost 0.62 kg less lean mass.” This remained significant after adjusting for intervention group, body size and change in fat mass.
Current research indicates that it is important to encourage older adults to consume sufficient protein, especially if they are on a hypocaloric diet, in order to reduce the loss of lean muscle mass. Excellent sources of protein include lean red meats, poultry, eggs and dairy products.
Read the abstract for the article, Lean mass loss is associated with low protein intake during dietary-induced weight loss in postmenopausal women by Melanie J Bopp and associates in JADA, 2008, 108 (7):1216-1220.
Download the BIC Nutrition Perspective, How Protein Helps Curb Hunger.
Review the Statistics Canada article, Adult obesity in Canada; measured height and weight.
This is an e-mail newsletter from the team of registered dietitians at the Beef Information Centre: a national non-profit organization committed to provide credible and timely information. Please share it with colleagues. By subscribing you agree to receive this newsletter.
To subscribe go to www.beefinfo.org/healthlink.cfm
To unsubscribe send a message to [email protected]. In the subject line type "unsubscribe to healthlink".
To send comments or to change your e-mail address, send a message to [email protected] and type the word "comments" in the subject line and your comments in the body of the e-mail.
For more information on beef & health visit www.beefinfo.org