Effect of Protein Intake on Visceral Abdominal Fat and Metabolic Biomarkers in Older Men With Functional Limitations: Results From a Randomized Clinical Trial.
Plain-language summary
This trial asked whether eating more protein than the recommended daily allowance cuts deep abdominal fat and improves heart-risk markers in older men with limited mobility. It randomly assigned 92 men aged 65 and over, all of whom were eating at or below the allowance, to 0.8 or 1.3 grams of protein per kilogram of body weight a day, each with or without weekly testosterone injections, for six months. Visceral fat, the fat packed around the organs, was measured in 56 of them and blood markers in 77. The higher protein group lost more visceral fat, a difference of 17.3 square centimeters, and that held whether or not the man was also getting testosterone. Fasting glucose, fasting insulin, leptin, adiponectin and the two inflammation markers did not show a significant change between the protein groups.
Key findings
- Men eating 1.3 g/kg/day of protein lost more visceral fat than those eating 0.8 g/kg/day.
- Higher protein intake did not improve heart-risk markers like blood sugar or inflammation.
- Testosterone use did not affect the results.
How to analyze the study yourself
- Study type
- Randomized trials assign people to groups by chance, so differences between groups are unlikely to come from who chose what.
- Population
- Functionally limited men aged 65 and older with usual protein intake ≤RDA
- Funding
- NIH extramural funding
- Takeaway
- In older men with limited mobility who were eating too little protein, this trial found that raising protein to 1.3 grams per kilogram of body weight a day cut visceral fat over six months, and that it did not move blood sugar, insulin or inflammation at all. The fat result is the real one and it did not depend on the testosterone arm of the trial. If you are older and eating below the recommendation, it may be worth getting protein up to roughly 1.3 grams per kilogram a day.