# 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

PMID: 39543330
Journal: Scientific reports
Published: 2024 Nov 14
Authors: Sindler D, Dostal T, Litschmannova M, Hofmann P, Knapova L, König LM, Elavsky S, Cipryan L

## 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.

## Population

- Adults with excessive weight or obesity from a parent lifestyle trial
- Sample size: 68
- Age: 42 +/- 10.2 years
- Sex: 16 men, 52 women
- Fitness level: Low physical activity/no regular exercise at baseline
- Health status: BMI 25-40 kg/m2, otherwise generally healthy, no physical or mental disease reported

## Methodology

- Secondary analysis of a four-arm randomized controlled trial
- 12 weeks
- Mixed lab and home walking HIIT with online questionnaires
- Randomized and controlled study design.

## Protocol

- Walking HIIT.
- Modality: Walking intervals.
- Work intervals: 3 min high-intensity walking.
- Recovery: 3 min low-intensity walking.
- Sets or repetitions: 4 intervals/session in weeks 1-4, 6 in weeks 5-8, 8 in weeks 9-12.
- Intensity: High intensity RPE 18-19; low intensity RPE 9-11.
- Session duration: 31, 43, then 55 min including 5 min warm-up and cool-down.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Intervals increased every 4 weeks from 4 to 6 to 8.
- VLCHF diet, combined VLCHF+HIIT, and control.
- Modality: Diet-only, diet plus walking HIIT, or usual lifestyle control.
- Work intervals: Same walking HIIT in combined group; none in diet-only/control.
- Recovery: Same walking HIIT in combined group; none in diet-only/control.
- Sets or repetitions: Same walking HIIT in combined group; none in diet-only/control.
- Intensity: VLCHF <=50 g carbohydrate/day; control usual diet and activity.
- Session duration: Same walking HIIT in combined group; none in diet-only/control.
- Frequency: Monthly dietitian contact for diet groups; no exercise control.
- Program length: 12 weeks.
- Progression: Diet counseling and monitoring; combined group also progressed intervals.

## Outcomes

### Life satisfaction
Status: mixed
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
Status: no clear change
Perceived stress did not differ significantly between groups.

PSS between-group p = 0.356

### SF-12 scores
Status: no clear change
SF-12 mental and physical health scores did not show significant between-group effects.

PHS p = 0.155; MHS p = 0.691

### Combined group
Status: improved
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

## Practical 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 And Adherence

- This mental-health analysis did not report exercise adverse events in detail.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/39543330/) (pubmed)
- [DOI](https://doi.org/10.1038/s41598-024-79378-z) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11564516/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.