Dr Jacob Wilson is the CEO of the Applied Science and Performance Institute. He is based in Tampa, Florida.
A ketogenic diet is typically high in fat, with moderate consumption of protein, and very low in carbs, typically just 5% of total daily calories, all of which come from leafy greens. This dietary approach forces your body to switch from using glucose as its main fuel source to ketones, which are compounds formed in the liver by the breakdown of fatty acids.
The ketogenic diet has received a lot of attention for its ability to aid with several diseases, including childhood epilepsy. More recently, studies have started to show benefits in an exercising population.
For instance, Dr Stephen Phinney has demonstrated that cycling time to exhaustion was maintained in highly-trained athletes following four weeks of ketogenic dieting, while a study by Paoli et al, published in the Journal of the International Society of Sports Nutrition, found that elite gymnasts lost body fat while maintaining strength after one month on the diet.
However, very few studies have investigated the effects of following a long-term ketogenic diet on resistance training performance.
We set out to investigate the impact of a ketogenic diet versus a traditional Western diet on changes in body composition, athletic performance and hormonal profiles in highly resistance-trained athletes.
We took 26 college males and assigned them into either a ketogenic diet (75% fat, 20% protein and 5% carbohydrates) or a traditional western diet (25% fat, 20% protein and 55% carbohydrates) for ten weeks. The ketogenic group then saw carbs reintroduced in weeks ten and 11 of up to 3g/kg of total bodyweight. Both groups undertook an intense resistance-training programme and we measured body composition, strength, power, and blood lipid profiles at the start, then at weeks 10 and 11.
Lean body mass increased to a greater extent in the ketogenic group (7.3%) compared to the traditional group (3.6%), and fat mass decreased in both the ketogenic group (-5.4%) and western groups (-6.2%). Strength and power increased to the same extent for both groups. No changes in total cholesterol occurred, however there was a trend for HDL to increase in the ketogenic subjects. Total testosterone actually increased by 20% in the ketogenic diet group compared to those following the Western diet.
Therefore, while both diets resulted in equal changes in performance, if you are training hard on a regular basis, our results indicate that following a high-fat, moderate-protein, and low-carb ketogenic diet may facilitate more favorable changes in body composition and hormonal profiles, compared to a traditional high-carb, Western diet.