PMID 35694163

Research
All papers

Impact of Intermittent Fasting Combined With High-Intensity Interval Training on Body Composition, Metabolic Biomarkers, and Physical Fitness in Women With Obesity

Batitucci G, Faria Junior EV, Nogueira JE, Brandão CFC, Abud GF, Ortiz GU, Marchini JS, Freitas EC

Question

Does intermittent fasting combined with HIIT improve body composition, metabolic biomarkers, and physical fitness in women with obesity?

Summary

This randomized trial in women with obesity found that 8 weeks of supervised circuit HIIT plus 5:2 intermittent fasting reduced weight/BMI and body fat while increasing fat-free mass. Dropout was high, especially in fasting-only and exercise-only groups, and some fasting-only dropouts reported dizziness and headaches.

Methodology

  • Women with degree-one obesity
  • 36 participants.
  • Mixed gym circuit.
  • Work intervals: 30-45 seconds.
  • Recovery: 30-15 seconds.
  • Intensity: 70-85% HRmax.
  • 25 minutes.
  • 3 sessions/week.
  • 8 weeks.
  • Randomized intervention trial
  • Body composition, Metabolic biomarkers, Physical fitness, and Adherence/tolerability were tracked.

Outcomes

Weight/BMI

Weight and BMI decreased only in IF+EX.

Weight p=0.012; BMI p=0.031.

Improved

Body fat/FFM

IF+EX and EX reduced body fat and increased fat-free mass.

Body fat IF+EX -4%, p<0.001; EX -2.3%, p=0.043; FFM IF+EX +3.3%, p<0.001; EX +2%, p=0.043.

Improved

Fitness

Aerobic capacity and strength improved in exercise groups.

Improved

Adherence

Dropout was high, especially in fasting-only and exercise-only groups.

IF+EX 25%, EX 45%, IF 50% dropout.

Safety concern

Insights

  • A progressive 25-minute circuit is adaptable, but fasting co-intervention complicates claims.
  • Fasting symptoms and dropout should be tracked explicitly.

Limitations

  • Short 8-week intervention.
  • High dropout and small final sample.
  • Baseline group imbalance.
  • Nonexercise activity not monitored.
  • IF group did not complete physical tests.

Safety

  • Exercise-related adverse events were not reported.
  • Three intermittent-fasting dropouts reported low diet acceptance due to dizziness and headaches.
  • Participants were screened to exclude diabetes, hypertension, dyslipidemia, heart disease, osteoarthritis, gastritis, regular medication, smoking/alcoholism, and malaise during prolonged fasting.
  • Exercise sessions were fully supervised with HR and RPE monitoring; dropout was high.