Some people may find that it’s easier to stick to a lower carbohydrate plan for only a few days a week rather than adopting a full-time keto diet, and this might help with adherence. The ketogenic diet was originally formulated by doctors to help treat people with epilepsy, and it was found especially effective in children who didn’t respond to medication. It’s not necessarily the diet itself that’s bad, but the way some people approach it. There’s also no added sugar and only 6 grams of net carbs, making a cold brew a great way to give yourself a satisfying boost between meals. Fat will make up a majority of the diet, at 75 to 80 percent, with protein making up the remainder. After Baseline testing on a carbohydrate-rich (HCHO) diet, they elected to follow a 3.5-week energy-matched dietary intervention of either HCHO or ketogenic low carbohydrate-high fat (LCHF) principles.
Details of dietary control are described briefly here; more details are described in prior work (18). Participants were allocated into HCHO and LCHF groups based on preference. Vegetarian and Order Keto Cycle diets each support blood sugar control. In addition to these tests, the laboratory ran quality control samples throughout testing and the results were within the established acceptable manufacturer ranges. Upon completion of the exercise test, the participants rested in the laboratory for a further 3 h, and received a standardized recovery shake (1.5 g·kg−1 CHO for both groups during Baseline and Restoration, or an isocaloric low CHO option for LCHF during Adaptation; both shakes included 0.3 g·kg−1 protein) at 30 min post-exercise to improve satiety. Thirty-two data sets were gathered from 30 participants who participated in one or more training camps. Participants and elite coaches contributed to the concept and implementation of the research camps, helping to prioritize the themes of interest and contributing to the design of the training program and test protocols. Thirty world-class athletes (25 male, 5 female race walkers; ages 27.7 ± 3.4 yr, BMI 20.6 ± 1.7 kg/m2) were recruited over three separate training camps during preparation for the 2016 Summer Olympic Games and the 2017 World Championships, and provided written informed consent in accordance with the Human Ethics Committee of the Australian Institute of Sport (ethics approval no. 20150802 and 20161201). Six male participants undertook two camps, however two of these data sets were incomplete due to insufficient tissue samples, resulting in 4 participants who had completed two camps being included in the final analysis.
Low energy availability (a mismatch between energy intake and the energy cost of exercise) occurs in both female and male athletes (2) and impairs bone health via direct (uncoupled bone turnover with increased resorption rates) and indirect (mediation by reproductive and metabolic hormones) mechanisms (1). In addition, carbohydrate (CHO) availability may also play a role in bone health. 18) completed a further testing block under conditions of acute high CHO availability. Whether these changes in markers of bone metabolism persist (or are amplified) after chronic exposure to low CHO availability around exercise remains unknown, but is of relevance in view of the promotion of a ketogenic low CHO-high fat (LCHF) diet to athletes and its putative benefits for endurance performance (11). To date, no studies have examined the effects of longer-term restriction of CHO at rest or in relation to exercise, although in animal models and children with intractable epilepsy, chronic adaptation to a ketogenic LCHF diet is associated with poor bone health (12-16). In view of our recent observations of increased post-exercise IL-6 concentrations in elite race walkers following a 3.5-week adaptation to a LCHF diet (17), we investigated the interaction of this diet and strenuous exercise on markers of bone modeling/remodeling as secondary outcomes of our larger study.
Blood samples were collected into a 3.5 mL EDTA BD Vacutainer Plus SST II tube, and allowed to clot by standing at room temperature for 2 h before centrifuging at 1,000 G for 10 min for subsequent analysis of serum markers of bone resorption (CTX), bone formation (P1NP) and overall bone metabolism (OC). The raw data for the analyses of serum bone modeling/remodeling markers are provided in the Supplementary Table to this publication. Statistical analyses were conducted using SPSS Statistics 22 software (INM, New York, USA) and R (R Core Team, 2018) with a significance level set at p ≤ 0.05. Normality of data was checked with a Shapiro-Wilk test and visual inspection of residual plots. In addition, two additional (male) data sets were excluded from the final analysis due to their inability to complete one of the experimental trials due to injury (unrelated to bone). 28 participants, 23 males, 5 females) with data for pre- (Baseline) and post-treatment (Adaptation), of which 18 trials (13 males, 5 females) also contributed to data from acute restoration to a HCHO diet (Restoration).