An enhanced protein regimen (1.4 g/kg/d with 30 g high-quality protein 4 times/d) provided greater benefits than RDA-level protein (0.8 g/kg/d) for physical function and body composition in older males with prediabetes and obesity undergoing a hypocaloric diet plus exercise intervention.
Key Findings
Results
The Enhanced Protein group showed greater improvement in Short Physical Performance Battery (SPPB) scores at both 3 and 6 months compared to the RDA Protein group.
At 3 months, the Enhanced Protein group improved SPPB by 1.5 ± 0.2 units versus 1.2 ± 0.3 units in the RDA Protein group (small Cohen's d = 0.23).
At 6 months, the effect size grew to a moderate Cohen's d = 0.68 in favor of the Enhanced Protein group.
SPPB is a validated measure of lower-extremity physical function in older adults.
Results
The Enhanced Protein group preserved significantly more fat-free mass (FFM) at 6 months compared to the RDA Protein group.
Enhanced Protein participants lost 0.8 ± 0.3 kg of FFM, compared with 1.5 ± 0.4 kg lost in the RDA Protein group.
This represented a moderate group effect (Cohen's d = 0.48; 95% CI: 0.26, 0.62).
FFM was measured by Bodpod air displacement plethysmography.
Results
The Enhanced Protein group lost more body weight at 3 months than the RDA Protein group.
Enhanced Protein participants lost 4.7% ± 0.9% of body weight at 3 months.
RDA Protein participants lost 3.1% ± 0.7% of body weight at 3 months.
Both groups were on hypocaloric diets combined with exercise.
Results
The Enhanced Protein group showed greater improvement in 6-minute walk test (6MWT) distance at 3 months compared to the RDA Protein group.
Enhanced Protein group increased 6MWT distance by 63.3 ± 12.8 m, compared with 34.4 ± 11.9 m in the RDA Protein group.
Mean difference was 29.0 m with a moderate effect size (Cohen's d = 0.53; 95% CI: <0, 1.19).
The 6MWT is a measure of functional aerobic capacity and endurance.
Results
The Enhanced Protein group demonstrated greater increases in handgrip strength at both 3 and 6 months compared to the RDA Protein group.
At 3 months, Enhanced Protein participants increased handgrip strength by 3.7 ± 1.2 kg versus 0.8 ± 1.0 kg in the RDA Protein group (MD: −2.8 kg; Cohen's d = 0.56; 95% CI: 0.21, 0.88).
The handgrip effect persisted at 6 months: Enhanced Protein increased by 3.0 ± 1.5 kg versus 1.2 ± 1.4 kg in RDA Protein (MD: −1.8; Cohen's d = 0.30; 95% CI: 0.15, 0.35).
Handgrip strength is a widely used proxy measure of overall muscle strength and sarcopenia risk.
Methods
The study enrolled older males (veterans) with obesity and prediabetes, a population underrepresented in obesity intervention trials.
Participants were males aged >55 years with BMI >30 kg/m² and prediabetes (HbA1c 6.0% ± 0.3%).
Mean age was 67.6 ± 7.0 years and mean BMI was 35.8 ± 4.3 kg/m².
64 participants were randomized equally: 32 to RDA Protein (0.8 g/kg/d) and 32 to Enhanced Protein (1.4 g/kg/d with 30 g high-quality protein 4 times/d).
The authors noted that older men are underrepresented in obesity intervention trials.
Methods
The enhanced protein intervention was designed to distribute high-quality protein across four daily eating occasions in addition to increasing total protein intake.
Enhanced Protein participants consumed 1.4 g protein/kg/d total.
Protein was distributed as 30 g of high-quality protein 4 times per day.
RDA Protein participants consumed 0.8 g/kg/d, consistent with current dietary recommendations.
Both groups followed a hypocaloric diet combined with exercise, with assessments at 3 and 6 months.
What This Means
This research suggests that older men with obesity and prediabetes can improve their physical function and preserve muscle mass more effectively during a weight-loss program if they consume higher amounts of protein spread throughout the day. In this pilot study, men who ate about 1.4 grams of protein per kilogram of body weight daily — including 30 grams of high-quality protein at each of four meals — performed better on standard measures of physical function, lost more overall body weight, kept more muscle mass, walked farther in six minutes, and had stronger handgrip than men who followed the standard dietary recommendation of 0.8 grams of protein per kilogram per day. Both groups combined their diets with exercise.
One particularly notable finding is that the benefit for physical function (measured by the Short Physical Performance Battery) grew larger over time, going from a small effect at 3 months to a moderate effect at 6 months in favor of the higher-protein group. Muscle preservation was also better in the higher-protein group at 6 months, with those participants losing roughly half the muscle mass lost by the standard-protein group (0.8 kg versus 1.5 kg). These findings are especially relevant because losing muscle during weight loss is a known concern for older adults and can worsen mobility and independence.
This research matters because older men are rarely included in weight-loss studies, even though obesity combined with prediabetes is common in this population and increases the risk of serious health problems. The results suggest that simply meeting the standard protein recommendation may not be enough to protect muscle and physical function when older men are trying to lose weight, and that a higher-protein approach distributed across meals could offer meaningful advantages. However, because this is a pilot study with a relatively small sample, larger trials are needed to confirm these findings.
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C. Bales, Marshall G. Miller, S. Mcdonald, Jessica T. Wallis, L. A. Yeager, R. Sloane, et al.. (2026). Influence of Protein Intake during Obesity Reduction on Physical Function and Body Habitus in Older Males with Prediabetes: A Pilot Study. Current Developments in Nutrition. https://doi.org/10.1016/j.cdnut.2026.109460