# High-intensity Interval Training Promotes the Shift to a Health-Supporting Dietary Pattern in Young Adults

PMID: 32245173
Journal: Nutrients
Published: 2020 Mar
Authors: Donati Zeppa S, Sisti D, Amatori S, Gervasi M, Agostini D, Piccoli G, Bertuccioli A, Rocchi MBL, Stocchi V, Sestili P

## Question

Does a 9-week progressive HIIT program change spontaneous dietary intake and body composition in healthy young adults?

## Summary

In healthy young adults, 9 weeks of supervised cycling HIIT did not reduce body weight but was accompanied by higher energy intake, higher fat-free mass, and a shift toward a diet pattern with more fish, nuts, seeds, oils, fruit, vegetables, and cereals.

## Population

- Healthy, normal-weight collegiate young adults who were not regularly active
- Sample size: 32
- Age: Men 22.6 +/- 1.7 years; women 21.5 +/- 0.8 years
- Sex: 20 men and 12 women
- Fitness level: Inactive; no more than one 60-min leisure walk or jog per week in the prior 3 months
- Health status: Healthy, normal weight, non-smokers, without major cardiovascular risk or relevant medication use

## Methodology

- Within-subject supervised training study
- 9 weeks
- Indoor cycling sessions with dietary monitoring before and during training

## Protocol

- Progressive indoor cycling HIIT.
- Modality: Indoor cycling.
- Work intervals: Intervals longer than 4 min in HR zone 2 and 2-4 min in HR zone 3.
- Recovery: Active recovery in HR zone 1.
- Sets or repetitions: 36 total sessions across 3 mesocycles.
- Intensity: Polarized HR-zone model: about 70% zone 1, 10% zone 2, 20% zone 3.
- Session duration: Warm-up, high-intensity interval section, and cool-down; exact session duration varied by mesocycle.
- Frequency: Progressed up to 5 sessions/week in the third mesocycle.
- Program length: 9 weeks.
- Progression: Three mesocycles increased weekly frequency and session duration.

## Outcomes

### Diet quality
Status: improved
Participants shifted toward a pattern with more health-supporting food choices.

Time effect across dietary and body-composition variables: Wilks lambda 0.153, F(57,215) = 3.314, p < 0.001; factor analysis described more fish, oils, nuts, seeds, fruit, vegetables, and cereals

### Energy intake
Status: worse/safety concern
Total energy intake increased during training.

+9.4% at T1, p = 0.001; +17.8% at T3, p < 0.01

### Fat-free mass
Status: improved
Fat-free mass increased while body weight did not significantly change.

Fat-free mass +3.8% at T3, p < 0.001; body weight no significant change

### Macronutrients
Status: mixed
Absolute protein, fat, and carbohydrate intake increased, but macronutrient proportions stayed similar.

Protein +18.5% at T3, p < 0.01; fat +19.4%, p = 0.015; carbohydrates +17.1%, p = 0.036

## Practical Insights

- Progressive HIIT may influence eating behavior even when participants are not instructed to change diet.
- Body-weight stability can mask increased fat-free mass during a young-adult HIIT program.
- Dietary intake should be monitored in HIIT studies because spontaneous compensation can occur.

## Limitations

- No non-exercise control group
- Small healthy young-adult sample
- Diet was self-reported by daily contact and photos
- Not designed to isolate which HIIT dose element drove dietary changes

## Safety And Adherence

- No exercise-related adverse events were reported in the article text; all participants completed the overall program.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/32245173/) (pubmed)
- [DOI](https://doi.org/10.3390/nu12030843) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146399/) (full text)

## Agent Guidance

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