Oranges have long been a favorite halftime snack for athletes, from pee-wee leagues to the pros. Turns out, citrus fruits are more than a healthy, hydrating snack. Ingesting a compound called p-synephrine (which is found in many citrus fruits) may help boost fat burn if ingested before exercise, according to British Journal of Clinical Pharmacology study.
Eighteen people took a supplement before exercising on a static bike. Researchers measured the cyclists’ energy expenditure (aka calorie burn) and blood pressure both before and after cycling. In one trial, the cyclists took a dose of p-synephrine, then waited an hour before exercising. In another trial, they received a placebo dose before undergoing the same testing and exercise. Ingesting the compound had no effect on calorie burn, heart rate, or blood pressure compared to the placebo.
Now here's the interesting part: The researchers ~ did ~ notice that the alkaloid increased the rate of fat oxidation and reduced carbohydrate oxidation at low and moderate intensity exercise. Translation: The cyclists burned more fat, instead of carbohydrates, when exercising at a low or moderate intensity. The data shows that ingesting the substance increased the participants' maximum capacity to burn fat, and even suggests that p-synephrine supplements could increase fat oxidation by 7g per hour of exercise.
It's worth noting that the active ingredient is found in super low concentrations in the fruit itself, which is why the people in the study took a supplement. While you can find p-synephrine in slightly higher concentrations in processed products like bitter orange extract, there's not enough scientific evidence to suggest that it's effective for weight loss purposes or safe for consumption, says the National Institutes of Health.
So, no, citrus fruits aren't a miracle fat-loss food. But snacking on a few orange slices before your next workout couldn't hurt! (Or sneak more citrus into your pre-workout meals with these creative citrus recipes.)