Acute p-synephrine ingestion increases fat oxidation rate during exercise

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Sports Nutrition

Background:

• p-Synephrine is a common ingredient in weight management supplements, often promoted for its thermogenic properties.
• Scientific evidence regarding p-Synephrine's efficacy in boosting fat metabolism during physical activity is limited.
• Understanding its effects on fat oxidation during exercise is crucial for informed supplement use.

Purpose of the Study:

• To investigate the acute effects of p-Synephrine ingestion on fat oxidation rates.
• To assess changes in fat metabolism at rest and during graded exercise.
• To determine if p-Synephrine influences energy expenditure and substrate utilization during exercise.

Main Methods:

• A double-blind, randomized, and counterbalanced study design was employed.
• Eighteen healthy participants ingested either p-Synephrine (3 mg/kg) or a placebo.
• Indirect calorimetry measured energy expenditure and substrate oxidation at rest and during a maximal cycle ergometer test.

Main Results:

• p-Synephrine did not alter resting energy expenditure or fat oxidation rates.
• During incremental exercise, p-Synephrine shifted the fat oxidation curve upwards, indicating increased fat utilization at various intensities.
• Maximal fat oxidation rate during exercise was significantly increased post-p-Synephrine ingestion.

Conclusions:

• Acute p-Synephrine intake enhances fat oxidation during exercise.
• It appears to reduce carbohydrate oxidation during low-to-moderate intensity exercise.
• These findings suggest a potential role for p-Synephrine in modulating substrate utilization during physical activity.