Effect of Protein Intake on Visceral Abdominal Fat and Metabolic Biomarkers in Older Men With Functional Limitations: Results From a Randomized Clinical Trial

J Gerontol A Biol Sci Med Sci. 2021 May 22;76(6):1084-1089. doi: 10.1093/gerona/glab007.


Background: It remains controversial whether high protein diets improve cardiometabolic profile. We investigated whether increasing protein intake to 1.3 g/kg/day in functionally limited older adults with usual protein intake ≤RDA (0.8 g/kg/day) improves visceral fat accumulation and serum cardiovascular risk markers more than the recommended daily allowance (RDA).

Methods: The Optimizing Protein Intake in Older Men Trial was a placebo-controlled, randomized trial in which 92 functionally limited men, ≥65 years, with usual protein intake ≤RDA were randomized for 6 months to: 0.8 g/kg/day protein plus placebo; 1.3 g/kg/day protein plus placebo; 0.8 g/kg/day protein plus testosterone enanthate 100 mg weekly; or 1.3 g/kg/day protein plus testosterone enanthate 100 mg weekly. In this substudy, metabolic and inflammatory serum markers were measured in 77 men, and visceral adipose tissue (VAT) was assessed using dual-energy x-ray absorptiometry in 56 men.

Results: Treatment groups were similar in their baseline characteristics. Randomization to 1.3 g/kg/day protein group was associated with greater reduction in VAT compared to 0.8 g/kg/day group (between-group difference: -17.3 cm2, 95% confidence interval [CI]: -29.7 to -4.8 cm2, p = .008), regardless of whether they received testosterone or placebo. Changes in fasting glucose, fasting insulin, HOMA-IR, leptin, adiponectin, IL-6, and hs-CRP did not differ between the 0.8 versus 1.3 g/kg/day protein groups regardless of testosterone use.

Conclusions: Protein intake >RDA decreased VAT in functionally limited older men but did not improve cardiovascular disease risk markers.

Clinical trials registration number: NCT01275365.

Keywords: Insulin resistance; Metabolic; Protein intake; Testosterone; Visceral fat.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorptiometry, Photon
  • Activities of Daily Living*
  • Aged
  • Biomarkers / blood
  • Blood Glucose / analysis
  • Dietary Proteins / administration & dosage*
  • Double-Blind Method
  • Humans
  • Intra-Abdominal Fat / anatomy & histology
  • Intra-Abdominal Fat / drug effects*
  • Male
  • Recommended Dietary Allowances
  • Testosterone / analogs & derivatives
  • Testosterone / therapeutic use


  • Biomarkers
  • Blood Glucose
  • Dietary Proteins
  • Testosterone
  • testosterone enanthate

Associated data

  • ClinicalTrials.gov/NCT01275365