Ever heard of ketones? You may have heard someone mention them when talking about low-carb, ‘ketogenic’ diets. Ketones are an alternative fuel source for our bodies. Under normal conditions, our bodies use glucose (sugar) for energy. That’s right, despite the low-carb craze in recent decades, our body’s main fuel source is carbohydrates! Ketones are made from fat when our body doesn’t have access to glucose. This can happen in a condition called diabetic ketoacidosis, which is related to uncontrolled diabetes, or be caused deliberately through dietary modification (extreme carbohydrate restriction).
Recently, taking ketones as a dietary supplement has been explored as a way to improve athletic performance. The idea behind this is to provide our muscles with an alternative, easily accessible fuel – especially for endurance training. Fat is a key energy source during endurance exercise, so think of it like a way to speed up our body’s ability to break down fat into energy.
A recent study in the Journal of Applied Physiology, Nutrition, and Metabolism explored the effectiveness of nutritional ketone salt supplements on exercise performance in healthy adult males. They found that the supplementation did improve fat oxidation, meaning that taking ketones improved energy availability for the athletes. However, time-trial power output was 7% lower in the athletes who took the ketones. In other words, ketones actually hindered the athletes’ ability to do high-intensity exercise.
The study findings mean that if you are a power athlete, like a sprinter, weight lifter, etc, ketones are not the supplement you should be looking for to improve performance. During any high-intensity exercise, where we need short bursts of power, our body relies on glucose. This explains why ketones had no benefit in the study here. If you do long, endurance-focused competitions, though, there may be a place for ketones to improve performance. Since ketone salts have substantial taste challenges (acetone is a ketone, as an example), incorporating them into foods or beverages may not be very welcome to typical consumers.