Caffeine increases whole-body fat oxidation during 1 h of cycling at Fatmax

source extracted confidence: high 2026-04-09
#adipose-tissue #caffeine #calorimetry-indirect #double-blind-method #energy-metabolism

Caffeine increases whole-body fat oxidation during 1 h of cycling at Fatmax

Ruiz-Moreno et al., 2021 | Eur J Nutr | Rct

Citation

Ruiz-Moreno Carlos, Gutiérrez-Hellín Jorge, ... Del Coso Juan. Caffeine increases whole-body fat oxidation during 1 h of cycling at Fatmax. Eur J Nutr. 2021-Jun;60(4):2077-2085. doi:10.1007/s00394-020-02393-z

Abstract

PURPOSE: The ergogenic effect of caffeine on exercise of maximum intensity has been well established. However, there is controversy regarding the effect of caffeine on shifting substrate oxidation at submaximal exercise. The aim of this study was to investigate the effect of acute caffeine ingestion on whole-body substrate oxidation during 1 h of cycling at the intensity that elicits maximal fat oxidation (Fatmax). METHODS: In a double-blind, randomized, and counterbalanced experiment, 12 healthy participants (VO2max = 50.7 ± 12.1 mL/kg/min) performed two acute experimental trials after ingesting either caffeine (3 mg/kg) or a placebo (cellulose). The trials consisted of 1 h of continuous cycling at Fatmax. Energy expenditure, fat oxidation rate, and carbohydrate oxidation rate were continuously measured by indirect calorimetry. RESULTS: In comparison to the placebo, caffeine increased the amount of fat oxidized during the trial (19.4 ± 7.7 vs 24.7 ± 9.6 g, respectively; P = 0.04) and decreased the amount of carbohydrate oxidized (94.6 ± 30.9 vs 73.8 ± 32.4 g; P = 0.01) and the mean self-perception of fatigue (Borg scale = 11 ± 2 vs 10 ± 2 arbitrary units; P = 0.05). In contrast, caffeine did not modify total energy expenditure (placebo = 543 ± 175; caffeine = 559 ± 170 kcal; P = 0.60) or mean heart rate (125 ± 13 and 127 ± 9 beats/min; P = 0.30) during exercise. Before exercise, caffeine increased systolic and diastolic blood pressure whilst it increased the feelings of nervousness and vigour after exercise (P < 0.05). CONCLUSION: These results suggest that a moderate dose of caffeine (3 mg/kg) increases the amount of fat oxidized during 1 h of cycling at Fatmax. Thus, caffeine might be used as an effective strategy to enhance body fat utilization during submaximal exercise. The occurrence of several side effects should be taken into account when using caffeine to reduce body fat in populations with hypertension or high sensitivity to caffeine.

Key Findings

In comparison to the placebo, caffeine increased the amount of fat oxidized during the trial (19.4 ± 7.7 vs 24.7 ± 9.6 g, respectively; P = 0.04) and decreased the amount of carbohydrate oxidized (94.6 ± 30.9 vs 73.8 ± 32.4 g; P = 0.01) and the mean self-perception of fatigue (Borg scale = 11 ± 2 vs 10 ± 2 arbitrary units; P = 0.05). In contrast, caffeine did not modify total energy expenditure (placebo = 543 ± 175; caffeine = 559 ± 170 kcal; P = 0.60) or mean heart rate (125 ± 13 and 127 ± 9 be

Outcomes Measured

  • blood pressure
  • systolic blood pressure
  • diastolic blood pressure

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition hypertension

MeSH Terms

  • Adipose Tissue
  • Caffeine
  • Calorimetry, Indirect
  • Double-Blind Method
  • Energy Metabolism
  • Humans
  • Oxidation-Reduction
  • Oxygen Consumption

Evidence Classification

  • Level: Rct
  • Publication Types: Journal Article, Randomized Controlled Trial
  • Vertical: caffeine

Provenance

Source extracted via PubMed E-utilities API on 2026-04-10