The study aimed to verify the effects of 5 weeks of ketogenic diet (KD) on some performance index in long distance triathletes

16 well trained male long distance Triathletes participates in the study (30.65 ± 10.77 years of age), with minimum one year of triathlon competition experience and 8-10 hours of training per week. All subjects had a personal interview made by a registered Medical Doctor about the diet intervention prior to the beginning of the study. Moreover participants were educated about the benefits and limitations of the two different dietary treatments and asked to nominate their preference for, or non-acceptance of, each of these interventions. Thus participants also decided liberally if participate for the diet intervention or not. This choice was decided to prevent any type of dropout in the KD group, considering that a free and conscious choices is better for the adherence on a strict diet like ketogenic diet . Investigators were thus able to allocate the athletes to their preferred treatment, while achieving suitable matching of groups based on age, body mass and aerobic power. All the participants were healthy and injured free, and not consuming a low carbs diet prior to the study. The diet macronutrient percentage distribution was the following: for ND the percentages were 25% of TDC (total daily calories), fat were 20% of TDC and carbohydrates represented the 55% of TDC; for KD the percentages were 68% fat, 26% protein and 6% carbohydrate. In the KD very low carbohydrate foods that simulate carbohydrates taste food like croissants, bread and cracked slices made by Le Gamberi Foods (Forlì, Italy), were used for a better compliance to the dietary intervention. Subjects undertaken an anthropometric test and two different cardiopulmonary tests with a professional cycloergometer (MARCA). The anthropometric measures were taken to evaluated body weight. height and body composition . After the body composition analysis subjects underwent to a maximal cardiopulmonary test (GXT) to evaluate the maximal oxygen consumption (VO2max). The following day subjects performed 60 minutes at 45% of PPO to assess endurance performance at ironman biking race-pace. The day after test session KD group started the KD 5 weeks. The Control Group (S) followed his habitual normo-caloric, balanced diet. The same order and procedures were conducted for testing the subjects post diet intervention. Anthropometric and performance test was conducted in the same order for each subjects and at the same time of the day. Blood ketones were measured each other day to ensure the compliance to KD

Inclusion Criteria:

• long distance Triathletes (8-10 hours of training per week), competing in half Ironman or Ironman
• no previous experience of low carbohydrate diet
• more than 3 years of training

Exclusion Criteria:

• recent (less than 6 months) musculoskeletal injuries
• more than 2 months without training in the last 2 years

Treatment and control were masked with A and B