Differential effects of intermittent energy restriction vs. continuous energy restriction combined high-intensity interval training on overweight/obese adults: A randomized controlled trial

Xu R, Cao YX, Chen YT, Jia YQ

Question

Does intermittent energy restriction plus HIIT produce different body composition, lipid, and cardiorespiratory effects than continuous energy restriction plus HIIT or normal diet plus HIIT?

Summary

In young adults with overweight or obesity, 4 weeks of cycling HIIT combined with either intermittent or continuous energy restriction reduced body size measures and improved some fitness and lipid markers. Intermittent restriction tended to produce larger body-composition changes, but between-diet differences were not statistically significant.

Methodology

Young adults with overweight or obesity
48 participants.
Cycle ergometer HIIT.
Work intervals: 3 minutes at 80% VO2max.
Recovery: 3 minutes at 50% VO2max.
Intensity: 80% VO2max work and 50% VO2max recovery; HR monitored.
30-minute interval session with 10-minute warm-up and 10-minute cooldown described.
5 sessions per week.
4 weeks.
Three-arm randomized controlled trial
Body composition, Blood lipids, and Cardiorespiratory fitness were tracked.

Outcomes

Body composition

Body weight, BMI, body fat percentage, waist circumference, and hip circumference decreased in all groups, with larger numerical reductions in the intermittent restriction group.

Significant time x group interactions for body weight F(2,28)=91.833, BMI F(2,28)=104.405, body fat percentage, waist, and hip circumferences, all p<0.001; post hoc between-diet differences were not significant.

Improved

Lipids

Some lipid markers changed over time, but diet group did not meaningfully alter lipid response to HIIT.

Time effects: total cholesterol p<0.001, triglycerides p=0.002, HDL-c p=0.037; LDL-c not significant.

Improved

VO2max

Absolute and relative VO2max improved over the 4-week HIIT intervention without significant group differences.

Absolute VO2max p=0.001 and relative VO2max p<0.001 over time; no significant between-group differences.

Improved

Insights

A short, frequent cycling HIIT block can be paired with dietary energy restriction in young adults with overweight/obesity.
Intermittent restriction may be a viable adherence strategy, but this small 4-week study does not prove superiority over continuous restriction.
Diet monitoring and make-up sessions were used to support compliance.

Limitations

Short 4-week intervention.
Young university sample limits generalizability.
Nine randomized participants withdrew because they could not adhere to diet or HIIT.
Between-group dietary superiority was not clearly established despite numerical trends.

Safety

Nine participants withdrew during the intervention because they could not adhere to the diet or HIIT; the authors reported no withdrawals due to adverse events.