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Published on: July 5, 2017
Influence of Protein Intake during Obesity Reduction on Physical Function and Body Habitus in Older Males with
Connie W Bales1,2, Marshall G Miller3, Shelley R McDonald1,2,3
1GRECC, Durham VA Health Care System, Durham, NC, United States.
Background:
Weight loss can improve health and function in older adults with obesity but may also accelerate loss of fat-free mass. Older men are underrepresented in obesity intervention trials; thus we tested higher protein intake plus exercise to help preserve muscle mass and physical function during weight loss in men with obesity and prediabetes.
Objectives:
We evaluated the effects of an enhanced protein weight loss intervention relative to a recommended dietary allowance (RDA)-level protein intervention in older males (veterans) with prediabetes and obesity.
Methods:
This study was a randomized controlled trial. Equal numbers of participants, males aged >55 y with obesity [body mass index (BMI), in kg/m2> 30] and prediabetes, were randomly assigned to either an RDA protein (0.8 g/kg/d; n = 32) or an enhanced protein (1.4 g protein/kg/d with 30 g high-quality protein 4 times/d; n = 32) hypocaloric diet plus exercise intervention, with outcome assessments at 3 and 6 mo., namely, Short Physical Performance Battery (SPPB) and fat-free mass (FFM) measured by Bodpod, body weight, body fat, waist circumference, 6-min walk time test (6MWT), 8-foot up-and-go test, and handgrip strength.
Results:
Baseline characteristics were as follows: BMI = 35.8 ± 4.3, mean age 67.6 ± 7.0 y, and hemoglobin A1c 6.0% ± 0.3%. For the SPPB score, the Enhanced Protein group had a greater benefit at both 3 mo (small Cohen's d = 0.23) and at 6 mo (moderate Cohen's d = 0.68). The Enhanced Protein group showed an increase in SPPB at 3 mo of 1.5 ± 0.2 units, compared with 1.2 ± 0.3 units for the RDA Protein group. The amount of weight lost was also more in the Enhanced Protein group at 3 mo (4.7% ± 0.9 compared with 3.1% ± 0.7). Additionally, participants in the Enhanced Protein group preserved more FFM at 6 mo (moderate group effect, Cohen's d = 0.48; 95% confidence interval [CI]: 0.26, 0.62), with a loss of 0.8 ± 0.3 kg compared with the RDA Protein arm, who lost 1.5 ± 0.4 kg. Other Enhanced Protein group effects at 3 mo included an increased distance walked in the 6MWT by 63.3 ± 12.8 m [mean difference (MD): 29.0 m; d = 0.53; 95% CI: <0, 1.19] and increased handgrip strength by 3.7 ± 1.2 kg (MD: -2.8 kg; d = 0.56; 95% CI: 0.21, 0.88), relative to the RDA Protein group, which had increases of 34.4 ± 11.9 m and 0.8 ± 1.0 kg for 6MWT and handgrip strength, respectively. The handgrip effect remained at 6 mo for Enhanced Protein, with an increase of 3.0 ± 1.5 kg compared with an increase of 1.2 ± 1.4 kg in RDA Protein (MD: -1.8; d = 0.30; 95% CI: 0.15, 0.35).
Conclusions:
The results provide preliminary evidence that an enhanced protein regimen can benefit older males with prediabetes, especially with regard to physical function and body composition.This trial was registered at clinicaltrials.gov as NCT03835416.
