Effects of a 15-Day Low Carbohydrate, High-Fat Diet in Resistance-Trained Men

Abstract

Waldman, HS, Krings, BM, Basham, SA, Smith, JW, Fountain, BJ, and McAllister, MJ. Effects of a 15-day low carbohydrate, high-fat diet in resistance-trained men. J Strength Cond Res XX(X): 000-000, 2017-This study examined the effects of a 15-day isocaloric low carbohydrate (<25% E), high-fat (>50% E) (LCHF) diet on physiological and metabolic alterations in resistance-trained (RT) men. College-aged RT men (n = 11) completed 4 V[Combining Dot Above]O2max tests using treadmill every 5 days during the 15-day trial. Blood was drawn intravenously pre-exercise across each experimental trial for insulin, cortisol, and glucose. Pulmonary data were collected and substrate oxidation (OXI) was calculated during exercise. Body mass decreased (p < 0.04) with no further changes in anthropometric measures. Time to exhaustion was not affected across each day. Insulin dropped below baseline values (p < 0.0005). Cortisol increased from baseline to day 5 (p < 0.004) but returned back to near baseline at day 10, whereas glucose remained within normal range throughout the duration of the study. Carbohydrate (CHO) OXI dropped (p < 0.001) from baseline to day 5, and fat OXI increased from baseline to day 5 (p < 0.0001). Heart rate decreased from baseline to day 5 (p < 0.001) and again from day 10 to 15 (p < 0.02). Oxygen uptake (V[Combining Dot Above]O2) decreased from day 5 to 10 (p < 0.0001). A nonketo LCHF diet appears to favor RT men by altering metabolic markers without decrements in aerobic performance and be a potential diet intervention used by coaches. However, the reported cardiorespiratory responses should be interpreted reasonably because of the possibility the subjects running economy improved over experimental trials.

Effect of carbohydrate restriction on oxidative stress response to high‐intensity resistance exercise

“…8 Previous findings from our laboratory demonstrated positive hormonal and metabolic responses from a non-ketogenic carbohydrate-restricted diet. 8 Therefore, further examination on OS markers is warranted.…”

“…The present investigation used a within, repeated measures design to examine the effects of a WD diet compared to a 15‐day LCHF diet on OS and inflammatory responses to exercise. Our laboratory has shown a two‐week dietary intervention to be sufficient to induce metabolic and hormonal adaptations in trained individuals; consequently, a 15‐day period was chosen for this study. All subjects were reported to the departmental laboratory for two testing sessions (one before and one after the diet protocol) following a 10‐hours fast between the hours of 0500 and 0800.…”

“…It is possible that less extreme carbohydrate‐restricted diets which allow for more flexibility in carbohydrate intake (<25% total calories) may induce similar physiological adaptations without such rigorous dietary restrictions . Previous findings from our laboratory demonstrated positive hormonal and metabolic responses from a non‐ketogenic carbohydrate‐restricted diet . Therefore, further examination on OS markers is warranted.…”

Effects of Short-Term Macronutrient Redistribution on Performance Parameters in Resistance Trained Males

“…Researchers and coaches alike have always had the impression that a diet high in carbohydrates is essential to propagate athletic potential and performance gains [7]. However, research has been performed describing this aforementioned need for carbohydrate consumption as being out dated [1][2][3][4][5][6][7][8][9]. Fleming and colleagues [2] examined the effects on athletic performance of adopting a high-fat, moderate-protein diet for a period of 6 weeks.…”

“…Most recently [9] evaluated the effects of a 15-day low carbohydrate, high-fat diet on physiological and metabolic alterations in resistance trained, college-aged men. The researchers found significant decreases in body mass without noted decrements in aerobic performance.…”