Effect of very-low-carbohydrate high-fat diet and high-intensity interval training on mental health-related indicators in individuals with excessive weight or obesity
Question
Do VLCHF diet, walking HIIT, or their combination change perceived stress, life satisfaction, and SF-12 mental/physical health scores in adults with excessive weight or obesity?
Summary
In adults with excessive weight or obesity, 12 weeks of walking HIIT, a very-low-carbohydrate high-fat diet, or both did not clearly improve mental health indicators versus control. The combined diet plus HIIT group improved life satisfaction more than HIIT alone, but the authors treated the mental-health findings as limited.
Methodology
- Adults with excessive weight or obesity from a parent lifestyle trial
- 68 participants.
- Walking intervals.
- Work intervals: 3 min high-intensity walking.
- Recovery: 3 min low-intensity walking.
- Intensity: High intensity RPE 18-19; low intensity RPE 9-11.
- 31, 43, then 55 min including 5 min warm-up and cool-down.
- 3 sessions/week.
- 12 weeks.
- Secondary analysis of a four-arm randomized controlled trial
- Life satisfaction, Perceived stress, Mental health score, and Physical health score were tracked.
Outcomes
Life satisfaction
Life satisfaction showed a between-group effect, with VLCHF+HIIT improving versus HIIT alone.
SWLS between-group p = 0.031, effect size = 0.133
Stress
Perceived stress did not differ significantly between groups.
PSS between-group p = 0.356
SF-12 scores
SF-12 mental and physical health scores did not show significant between-group effects.
PHS p = 0.155; MHS p = 0.691
Combined group
Within-group improvements occurred for life satisfaction, stress, and physical health in VLCHF+HIIT.
VLCHF+HIIT SWLS +0.70, PSS -0.30, PHS +2.01; within-group changes marked significant in article table
Insights
- Walking HIIT can be structured as progressive 3 min/3 min intervals with RPE targets.
- Mental-health effects were not clearly attributable to HIIT alone in this secondary analysis.
- Polar watch uploads were used for remote adherence monitoring.
Limitations
- Secondary analysis
- Questionnaire completer sample smaller than parent randomized sample
- Baseline stress imbalance
- Control group also improved on some measures
- Diet and exercise effects are hard to separate in the combined arm
Safety
- This mental-health analysis did not report exercise adverse events in detail.