# Maintenance of time-restricted eating and high-intensity interval training in women with overweight/obesity 2 years after a randomized controlled trial

PMID: 40280987
Journal: Scientific reports
Published: 2025 Apr 25
Authors: Haganes KL, Hawley JA, Lydersen S, Moholdt T

## Question

Do women with overweight or obesity maintain TRE and/or HIIT 2 years after a supervised 7-week randomized trial, and are cardiometabolic outcomes maintained?

## Summary

This 2-year follow-up of the TREHIIT randomized trial asked whether women with overweight or obesity continued time-restricted eating or HIIT after a 7-week supervised intervention. About one-third of the original HIIT group and 45% of the combined TREHIIT group still reported doing HIIT after 2 years, but cardiometabolic between-group differences were not statistically significant at the stricter threshold. Participants described HIIT as time-efficient and mastery-building, while lack of time, pain, injury, motivation, and exertion discomfort were common barriers.

## Population

- Women with overweight or obesity from the TREHIIT trial.
- Sample size: 59
- Age: 39.0 (SD 6.1) years at follow-up
- Sex: Women only
- Fitness level: Not reported as trained; overweight/obesity lifestyle-intervention sample.
- Health status: BMI about 30.7 kg/m2 at follow-up; overweight/obesity.

## Methodology

- Two-year follow-up of a randomized controlled trial, analyzed by original group assignment.
- 7-week original intervention plus 2-year follow-up
- Original supervised lab-based exercise in Norway; follow-up laboratory assessments and questionnaires.
- Randomized and controlled study design.

## Protocol

- TREHIIT trial HIIT.
- Modality: Treadmill running or stationary cycling.
- Work intervals: 4 min and 1 min intervals.
- Recovery: 3 min active recovery or 1 min low-intensity standing/walking.
- Sets or repetitions: 2 weekly sessions of 4 x 4 min and 1 weekly session of 10 x 1 min.
- Intensity: 90-95% HRmax or maximum sustainable 1-min intensity.
- Frequency: 3 sessions/week.
- Program length: 7 weeks.
- TRE and no-intervention control.
- Modality: Dietary timing or no intervention.
- Program length: 7 weeks.

## Outcomes

### HIIT maintenance
Status: mixed
4/12 original HIIT participants and 9/20 TREHIIT participants still reported undertaking HIIT after 2 years.

HIIT 33%; TREHIIT 45%.

### Cardiometabolic between-group outcomes
Status: no clear change
No statistically significant between-group differences at p<0.01 after 2 years.

Non-significant body mass HIIT vs CON p=0.019 and visceral fat TREHIIT vs CON p=0.015.

### Within-group body composition and fitness
Status: improved
HIIT and TREHIIT had lower body mass, fat mass, and visceral fat area and higher VO2peak versus baseline at 2 years.

HIIT fat mass -4.2 kg p<0.001; visceral fat -19 cm2 p<0.001; VO2peak +2.7 mL/kg/min p=0.002.

### Experience and barriers
Status: mixed
HIIT was rated favorably and valued for time-efficiency/mastery, but lack of time, injury, pain, motivation, difficulty, and exertion discomfort were barriers.

HIIT rating 7.5 (2.1)/10.

## Practical Insights

- A short supervised HIIT block may seed longer-term exercise habits for some users.
- Long-term adherence support should address time, injury/pain, motivation, and exertion discomfort.
- Adding exercise variety may help people who enjoy HIIT but do not want only HIIT.

## Limitations

- Only a subset attended 2-year follow-up
- Self-selection bias
- Recall bias from self-reported continuation
- No objective adherence or interim physical activity data
- Limited power and multiple comparisons

## Safety And Adherence

- Injury and pain were reported as barriers to maintaining HIIT.
- No formal adverse-event count was reported in this follow-up article.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40280987/) (pubmed)
- [DOI](https://doi.org/10.1038/s41598-025-95743-y) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12032017/) (full text)

## Agent Guidance

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