In the news: Protein for Older People & Those Using GLP-1 Meds for Weight Loss

What Leads to Age-Related Muscle Loss?

Older adults are often susceptible to sarcopenia, or loss of muscle mass. The January issue of Staying Healthy offers some tips for evidence-based ways to lessen the effects of this condition (See SBH.com, resources). One of those strategies is to consume adequate protein and to practice resistance exercises as well.

Muscle tissue is constantly turning over, with muscle protein being broken down and rebuilt (muscle protein synthesis or MPS). The balance between the rates of muscle protein breakdown and synthesis determines changes in muscle mass.

Declines in muscle mass, strength and function with aging are due to many factors. One important factor is something called anabolic resistance, which results in a blunted MPS response to protein. This factor is why older adults may benefit from including more protein in their diet.

It's been found, for example, that young adults can achieve a maximum MPS response after a single meal containing 0.24 grams of protein per kilogram (2.2 pounds) of body weight, while older adults needed close to double that amount in a single meal to achieve the same feat.

Protein May Help Mature Adults Keep Muscle

It has also been observed in population health studies that higher protein intake is linked to stronger grip strength, better physical function and higher muscle mass in older people.

While most Americans are eating sufficient protein, how much might be needed by mature adults to deter loss of muscle mass and strength? A newly published small, but controlled trial(1) offers insight into that question.

Twenty-six participants, average age of 60, diabetic and showing signs of sarcopenia, were randomly assigned to a higher protein diet of 1.2 to 1.5 grams of protein per Kg body weight per day, or a lower protein diet of 0.8-1.0 grams protein per Kg body weight per day. At the end of 12 weeks, muscle mass decreased in the arms and legs of the lower vs. higher protein group.The lower protein eaters lost 4 lbs. while higher protein consumers gained about 1 lb.

The higher vs. lower protein group also had better physical function as measured by hand grip strength, walking speed, and a balance test. No improvement, however, was seen in the test that measures how many times one can go from sitting to standing in a set period of time.

Not many studies have attempted to directly assess protein needs relative to muscle mass in the elderly, but a previous 24-week study in older non-diabetics also found that higher protein levels – 1.6 vs 1.2 grams per Kg body weight daily – increased muscle mass.

The take home message: Evidence suggests that older individuals need more protein than the RDA or Recommended Daily Allowance of 0.8 grams per Kg body weight daily. It appears that about 1.5 to 1.6 grams protein per Kg body weight is more beneficial – that’s about 102–109 grams daily for a 150 lb. person.

Protein/Exercise Fights GLP-1 Muscle Loss

The prescribed use of glucagon-like peptide 1 receptor agonist (GLP-1) drugs for overweight has skyrocketed. But one common drawback is muscle loss, particularly during rapid weight loss. Some studies have reported that 20 to 50% of the total weight lost is due to loss of muscle.

A new study(2) following 200 obese or overweight participants for 6 months found that educating them in resistance training (3 times weekly) and eating adequate protein can minimize muscle loss when using GLP-1 drugs. Protein recommendations were individualized, but generally above the RDA. Women lost 12% of body weight, with minimal muscle loss, while men showed similar results.

References

1. Argyropoulou D, et al. The effects of dietary protein on physical performance and body composition in middle age and older people having type II diabetes mellitus: a randomized pilot study. Eur J Nutr. 64(1):63, 2005.
2. Resistance Training + Protein May Lower GLP-1 RA Muscle Loss - Medscape - April 15, 2025.