by David Greenwalt
It’s now common knowledge that protein intake on the order of a gram of protein per pound of lean body mass per day is getting pretty close to ideal for middle-aged and younger dieters and fitness enthusiasts who care, at all, about keeping or adding muscle. Refreshingly, not surprisingly, the same holds true for older adults.
As people age they lose muscle mass (sarcopenia) and gain fat mass. These effects are aggravated via lesser physical activity, more skeletal muscle inflammation and leptin resistance (the master hormone produced by fat cells that tells the brain, among other things, you’re full and can stop eating). According to the CDC more than 35% of those older than 60 have a body mass index (BMI) greater than 30 (obese).
From a purely mathematical perspective you can lose weight (fat and muscle) by moderately restricting caloric intake. However, without a proper exercise regimen and proper protein intake 25% or more of the mass lost can be muscle.
In a meta-analysis and systematic review researchers included 20 studies in which participating men, aged 50 and up, restricted energy intake without any form of exercise. The authors compared those who took in less than 25% of their energy as protein or less than 1g/kg/day and those who consumed greater than 25% or 1g/kg/day. Participants reviewed had been restricting energy intake anywhere between 8 weeks and 2 years.
Both groups (high and normal protein intake) had similar total body weight loss, but the higher protein group lost more fat mass and lost less lean mass (muscle).
“The greater fat mass loss with higher protein diets may be related to higher protein-diet–induced increases in whole body energy expenditure, including resting energy expenditure and thermic effect of feeding. In addition, higher protein diets may increase fat oxidation in overweight and obese subjects.”
Not unlike the middle-aged and youngens moderate calorie restriction combined with protein intake of 1.2-1.5g/kg/day (1.1 to 1.5 grams per kilogram of body weight per day) was found to be ideal. The standard protein recommendation for the non-losing weight stable is 0.8g/kg/day.
These findings are very encouraging for those north of 50. It’s especially critical they at least maintain the muscle mass they have. With few exceptions the older population is starting their weight-loss regimen with less lean body mass than their younger counterparts. The last thing they need is to lose more muscle as they’re trying to get in better shape through fat loss.
Kim, J. E., O’Connor, L. E., Sands, L. P., Slebodnik, M. B., & Campbell, W. W. (2016). Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis. Nutrition reviews, 74(3), 210-224.