Does caffeine ingestion before a short-term sprint interval training promote body fat loss?
Question
Does caffeine before a single SIT session increase energy expenditure, and does caffeine before 2 weeks of SIT increase body fat loss versus placebo?
Summary
In 20 physically active men, 2 weeks of cycling sprint interval training reduced body fat only in the group taking 5 mg/kg caffeine before each session. Caffeine increased post-exercise energy expenditure after the first session and no caffeine-related side effects were reported.
Methodology
- Healthy physically active men.
- 20 participants.
- Cycling.
- Work intervals: 30 seconds all-out.
- Recovery: 15 seconds self-paced active recovery.
- Intensity: All-out; 5 mg/kg caffeine 1 hour before session.
- About 12.75 minutes plus warm-up.
- 6 sessions over 2 weeks.
- 2 weeks.
- Placebo-controlled double-blind randomized training study
- Body fat, Energy expenditure, and Side effects were tracked.
Outcomes
Post-exercise EE
Caffeine increased post-exercise energy expenditure versus placebo.
469.2 +/- 58.6 vs 392.0 +/- 70.3 kJ, p=0.02.
Body fat
Body fat decreased in caffeine but not placebo.
Group x time p=0.01; CAF -1.0 +/- 0.7 percentage points.
Body mass
Body mass and BMI did not change in either group.
All p>0.47.
Insights
- Caffeine may increase post-exercise energy expenditure after all-out SIT, but evidence is narrow.
- The 13 x 30-second/15-second recovery format is intense and best treated as advanced.
Limitations
- Small sample.
- Physically active men only.
- Short 2-week duration.
- Skinfolds rather than DEXA.
- Baseline body mass and body fat were somewhat higher in caffeine group.
Safety
- No caffeine-related side effects were reported.
- Participants were instructed to report caffeine-related side effects and to avoid caffeine-containing foods/beverages before tests and sessions.
- The study reported successful blinding, with 87% not correctly guessing supplement assignment; no dropout or injury data were otherwise highlighted.