Caffeine Optimizes HIIT Benefits on Obesity-associated Metabolic Adversity in Women.
Study Goal
The researchers aimed to determine whether HIIT, with or without caffeine supplementation, could ameliorate obesity-related adversities such as excessive body fat, metabolic endotoxemia, and reduced fitness in women with obesity.
Results Summary
HIIT alone reduced body fat, increased muscle mass, and improved fitness but also increased glucose and insulin levels and endotoxemia. Caffeine supplementation with HIIT mitigated these adverse effects while maintaining the benefits.
Population
24 women with obesity (BMI ≥ 27 kg/m², body fat ≥ 40%).
Effective Dosage
Caffeine (3 mg/kg body weight) before each training session.
Duration
8 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
high-intensity interval training (HIIT) alone | increase | OGTT glucose at 90 min | women with obesity | - | increased | #1 |
high-intensity interval training (HIIT) alone | increase | OGTT insulin at 60 min | women with obesity | - | increased | #2 |
high-intensity interval training (HIIT) alone | increase | OGTT insulin | women with obesity | 28.3% | induced 28.3% higher | #3 |
high-intensity interval training (HIIT) alone | increase | OGTT glucose | women with obesity | 14.5% | induced 14.5% higher | #4 |
high-intensity interval training (HIIT) alone | increase | lipopolysaccharide endotoxins | women with obesity | 31% | induced a 31% increase in | #5 |
high-intensity interval training (HIIT) with caffeine supplementation | decrease | OGTT glucose at 120 min | women with obesity | - | decreased | #6 |
high-intensity interval training (HIIT) with caffeine supplementation | decrease | OGTT glucose | women with obesity | 19.1% | decreased OGTT glucose by 19.1% | #7 |
high-intensity interval training (HIIT) with caffeine supplementation | no change | OGTT insulin | women with obesity | - | without affecting | #8 |
high-intensity interval training (HIIT) with caffeine supplementation | no change | OGTT insulin | women with obesity | - | without changing | #9 |
high-intensity interval training (HIIT) with caffeine supplementation | no change | lipopolysaccharide endotoxins | women with obesity | - | did not affect | #10 |
high-intensity interval training (HIIT) alone | decrease | body fat percentage | women with obesity | - | reduced | #11 |
high-intensity interval training (HIIT) alone | increase | muscle mass | women with obesity | - | increased | #12 |
high-intensity interval training (HIIT) alone | decrease | testosterone | women with obesity | - | reduced | #13 |
high-intensity interval training (HIIT) alone | increase | cardiorespiratory and anaerobic capacity | women with obesity | - | increased | #14 |
high-intensity interval training (HIIT) with caffeine supplementation | decrease | body fat percentage | women with obesity | - | reduced | #15 |
high-intensity interval training (HIIT) with caffeine supplementation | increase | muscle mass | women with obesity | - | increased | #16 |
high-intensity interval training (HIIT) with caffeine supplementation | decrease | testosterone | women with obesity | - | reduced | #17 |
high-intensity interval training (HIIT) with caffeine supplementation | increase | cardiorespiratory and anaerobic capacity | women with obesity | - | increased | #18 |
PURPOSE: We investigated whether obesity adversities such as excessive body fat, compensatory hyperinsulinemia, metabolic endotoxemia, irregular androgenicity, and reduced cardiorespiratory and anaerobic fitness are ameliorated by high-intensity interval training (HIIT) with or without caffeine supplementation in women with obesity. METHODS: Twenty-four women with obesity (Asian cutoff point body mass index ≥ 27 kg·m, body fat = 40%) were evenly randomized to caffeine (CAF) and placebo (PLA) trials for an 8-wk HIIT program (10 × 1-min sprints, interspersed by 1-min rest). CAF (3 mg·kg·bw) and PLA were supplemented before each training session. Body fat was assessed by dual-energy x-ray absorptiometry before and after training together with assessments of glucose tolerance (oral glucose tolerance test, or OGTT), lipopolysaccharide endotoxins, testosterone, cardiorespiratory, and anaerobic fitness. RESULTS: Significant interaction between HIIT and CAF was found for OGTT glucose and OGTT insulin levels (P = 0.001 and P = 0.049 respectively). HIIT-alone increased glucose at 90 min (P = 0.049) and OGTT insulin at 60 min (P = 0.038). Conversely, HIIT with CAF decreased OGTT glucose at 120 min (P = 0.024) without affecting OGTT insulin. HIIT-alone induced 28.3% higher OGTT insulin (effect size d = 0.59 for area under the curve) and 14.5% higher OGTT glucose (d = 0.28). Conversely, HIIT with CAF decreased OGTT glucose by 19.1% (d = 0.51 for area under the curve) without changing OGTT insulin. HIIT-alone effects on glycemia and insulinemia were concurrent with a 31% increase in lipopolysaccharide endotoxins (P = 0.07; d = 0.78; confidence interval, 5.7-8.7) in the PLA but not in CAF treatment (P = 0.99; d = 0.003; confidence interval, 6.5-10.6), although endotoxin level remained within the recommended healthy thresholds. Furthermore, either HIIT alone or with CAF reduced body fat percentage (P < 0.001, ANOVA main training effects), increased muscle mass (P = 0.002), reduced testosterone (P = 0.005), and increased cardiorespiratory and anaerobic capacity (P < 0.001). CONCLUSIONS: HIIT induces fat loss and decreases androgenicity in women with obesity. However, its side effects such as endotoxemia and hyperinsulinemia are ameliorated by caffeine supplementation.