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

Abstract

BACKGROUND\nIt 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 RDA.\n\n\nMETHODS\nThe 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.\n\n\nRESULTS\nTreatment 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: -17.3cm 2, 95%CI, -29.7 to -4.8\xa0cm 2, p=0.008), 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 vs 1.3-g/kg/d protein groups regardless of testosterone use.\n\n\nCONCLUSIONS\nProtein intake >RDA decreased VAT in functionally-limited older men but did not improve cardiovascular disease risk markers.