Ketogenic diet does not affect strength performance in elite artistic gymnasts
Antonio Paoli1,2*, Keith Grimaldi3, Dominic D’Agostino4, Lorenzo Cenci5, Tatiana Moro1, Antonino Bianco6 and Antonio Palma6
Author Affiliations
1 Physiological Laboratory – Department of Biomedical Sciences, University of Padova, Padova, Italy
2 Human Movement Sciences School, University of Padova, Padova, Italy
3 Biomedical Engineering Laboratory, Institute of Communication and Computer Systems, National Technical University of Athens, Athens, Greece
4 Department of Molecular Pharmacology & Physiology College of Medicine, University of South Florida, Tampa, FL, USA
5 Tisanoreica Study Center, Lonigo, Vicenza, Italy
6 Department of Sports and Exercise Science (DISMOT), University of Palermo, Palermo, Italy
For all author emails, please 
Journal of the International Society of Sports Nutrition 2012, 9:34 doi:10.1186/1550-2783-9-34

Despite the increasing use of very low carbohydrate ketogenic diets (VLCKD) in weight control and management of the metabolic syndrome there is a paucity of research about effects of VLCKD on sport performance. Ketogenic diets may be useful in sports that include weight class divisions and the aim of our study was to investigate the influence of VLCKD on explosive strength performance.
8 athletes, elite artistic gymnasts (age 20.9 ± 5.5 yrs) were recruited. We analyzed body composition and various performance aspects (hanging straight leg raise, ground push up, parallel bar dips, pull up, squat jump, countermovement jump, 30 sec continuous jumps) before and after 30 days of a modified ketogenic diet. The diet was based on green vegetables, olive oil, fish and meat plus dishes composed of high quality protein and virtually zero carbohydrates, but which mimicked their taste, with the addition of some herbal extracts. During the VLCKD the athletes performed the normal training program. After three months the same protocol, tests were performed before and after 30 days of the athletes’ usual diet (a typically western diet, WD). A one-way Anova for repeated measurements was used.
No significant differences were detected between VLCKD and WD in all strength tests. Significant differences were found in body weight and body composition: after VLCKD there was a decrease in body weight (from 69.6 ± 7.3 Kg to 68.0 ± 7.5 Kg) and fat mass (from 5.3 ± 1.3 Kg to 3.4 ± 0.8 Kg p < 0.001) with a non-significant increase in muscle mass.
Despite concerns of coaches and doctors about the possible detrimental effects of low carbohydrate diets on athletic performance and the well known importance of carbohydrates there are no data about VLCKD and strength performance. The undeniable and sudden effect of VLCKD on fat loss may be useful for those athletes who compete in sports based on weight class. We have demonstrated that using VLCKD for a relatively short time period (i.e. 30 days) can decrease body weight and body fat without negative effects on strength performance in high level athletes.
Very low carbohydrate Ketogenic diet; Body composition; Weight loss; Strength; Gymnastic
Many procedures used for body weight reduction by athletes in sports that include weight categories lead to a series of negative side effects which directly influence physiological efficiency during sports performance. The practice of rapidly losing a significant amount of weight, through low calorie diets, deliberate dehydration, saunas etc., just before competition, is widespread . These traditional methods are often unsafe and typically impair health, physiological function, water balance, electrolytes, glycogen and lean body mass and are sometimes illegal as with the use of diuretics .
However for athletes competing in sports divided into weight categories a safe method of weight loss that does not impair performance can be a legitimate and important tool. For example, bodybuilders regularly need to reduce fat and/or weight before competition preferably without affecting muscle strength or muscle size [7] and a VLCKD (very low carbohydrate ketogenic diet) is commonly used to achieve this. VLCKD is a diet in which the daily carbohydrate intake is below 30 g and this restriction limits glucose availability to tissues, stimulating ketogenesis in the liver. The physiological function of ketosis is to supply the heart and central nervous system (CNS) with a high energy metabolic substrate during reduced glucose availability – by this mechanism ketones allowed our ancestors to survive and remain efficient even when deprived of food . On this basis the ketosis induced by a VLCKD may be defined as “physiological ketosis” to distinguish it from the severe pathological ketosis (or ketoacidosis) commonly seen in uncontrolled diabetes . The use of low carbohydrate ketogenic diets for weight loss, despite their efficacy, has been an area of controversy. In the last few years though an increasing amount of evidence has accumulated concerning the positive effects on short term weight loss, metabolic profile with regards to insulin sensitivity, glycemic control and serum lipid values . These effects appear potentially very attractive for athletes needing to lose fat mass quickly but, curiously, despite the huge amount of scientific literature about ketogenic diets, their influence on sport performance remains poorly investigated. Recently Kreider and colleagues studied the effect of a specific exercise program in overweight woman with a VLCKD or normal carbohydrate content diet , but only few papers that focus specifically on the influence of VLCKD on sports performance have been published, and with conflicting results: showing benefits , no effect or impairment .
The present study set out to investigate if a VLCKD could be useful for athletes, especially for those engaged in sports involving weight categories where weight loss without negative changes in the body composition (i.e. loss of muscle mass) and performance is often needed. To the best of our knowledge no previous study has investigated the influence of a VLCKD on strength performance and on explosive strength performance in competitive athletes.