(PTFS20-05-24) No Effect of a Higher Fat Diet on Physical Performance

Objectives: The logistical constraints posed by the weight and volume of rations utilized during military operations may negatively impact energy intake. Increasing dietary fat content may help meet energy demands and minimize food weight. However, the effects of adopting a higher-fat diet for a brief period (i.e., 6 d) on physical performance require further investigation. This randomized, crossover study aimed to determine the impact of a higher-fat diet (HF; 40% of total kcal) on physical performance and gastrointestinal (GI) symptoms as compared to a standard fat diet (SF; 30% of total kcal).

Methods: Twenty healthy adults [22 ± 5 y, body mass: 80.3 ± 12.2 kg, VO_2peak: 47.9 ± 9.0 mL/kg/min] consumed controlled, protein-matched HF and SF diets for 6 d, separated by ≥7 d. To assess physical performance, participants completed vertical jump, 4-mile time trial, and time to exhaustion (85% VO_2peak) tests and the Army Combat Fitness Test (ACFT, 0-600 pts; 3-repetition maximum deadlift, standing power throw, hand-release pushup, sprint-drag-carry, plank hold, and 2-mile time trial) immediately before and after each intervention. GI symptoms were assessed daily.

Results: Relative to SF, HF consumed more fat (% of total kcal; 41 ± 3% vs 29 ± 4%; p< 0.0001), and less carbohydrate (43 ± 3% vs 57 ± 2%; p< 0.0001). There were no significant differences in energy intake (HF: 2493 ± 310 kcal/d vs SF: 2517 ± 295 kcal/d; p=0.61), or body mass change (HF: -0.84 ± 0.96 kg vs SF: -0.56 ± 1.6 kg; p=0.54). After adjusting for baseline, ACFT score (HF: 503 ± 56 vs SF: 494 ± 55; p=0.05) tended to be higher in HF. No between-group differences in any other performance measure (p >0.26) or GI symptoms (p=0.46) were observed.

Conclusions: Short-term consumption of a higher-fat diet neither impaired nor meaningfully improved measures of physical performance and did not cause GI distress. Findings provide evidence to support the use of higher fat rations for short durations as a practical strategy to mitigate energy decrements when lower weight and volume rations are required.

Funding Sources: US Army Combat Capabilities Development Command Soldier Center, Natick, MA, USA

DISCLAIMER: Authors’ views do not reflect official DoD or Army policy.