The following study looked at 9 placebo-controlled studies (the gold standard of scientific investigation), and found no benefit from protein:
Conclusions: These results indicate that amino acid/protein supplements did not increase lean body mass gain and muscle strength significantly more than placebo in a diverse elderly population.
This next one was an exhaustive review of 37 studies from January 2000 to October 2013 that addressed the prevalence of sarcopenia and the effect of nutrition and exercise.
In a nut shell:
- Up to a third (33%) of adults over 50 (living in the community, not in a care setting where, as you’d expect, the prevalence is higher) have some degree of muscle loss or reduced muscle function.
- “Protein supplements have not shown consistent benefits on muscle mass and function.”
- “Exercise interventions, especially those based on resistance training, may have a role in improving muscle strength and physical performance (moderate quality evidence), but not muscle mass.”
There are quite a few doctors and nutrition coaches advising people to consume more protein as they age to stem loss of muscle mass or strength (sarcopenia). Not only is the jury still out on whether eating more protein will prevent or turn around muscle loss, but it could be harmful. Eating more protein stresses the kidney, and, as we saw, causes detrimental calcium losses, and increases the risks for kidney stones and renal disease.
Regarding fat… Insulin resistance and chronic inflammation play a role in muscle loss as we age. Both of those are increased by dietary fat, especially saturated fat. Eat butter? It’s just not a good idea.