Theses and Dissertations

Issuing Body

Mississippi State University


Smith, JohnEric William.

Committee Member

McAllister, Matthew J.

Committee Member

Fountain, Brent J.

Committee Member

Lamberth, John.

Date of Degree


Document Type

Dissertation - Open Access


Kinesiology (Exercise Science)

Degree Name

Doctor of Philosophy


College of Education


Department of Kinesiology


The effects of low carbohydrate (CHO), high fat (LCHF) diets on adaptations to high-intensity exercise have recently gained interest. Consuming a LCHF may potentially decrease the ability to use CHO during exercise and impair high-intensity exercise adaptations. Therefore, the purpose of this investigation was to examine the importance of CHO timing while consuming a LCHF diet and completing a high-intensity exercise program. Eighteen resistance trained males were randomized into two treatment groups. Both groups completed 6 weeks of a high-intensity exercise training program with the first 2 weeks serving as familiarization to resistance training (RT) 3 days per week and completing one high-intensity interval training (HIIT) session. During the final 4 weeks, participants trained 5 days per weeks, three days of RT and two days of HIIT (repeated 30 s all out sprints). All participants consumed a LCHF diet (~25%, ~25%, and ~50% of daily kilocalorie intake coming from CHO, protein, and fat). The supplemented (SUPP) group (n=9) consumed 30 g of CHO during exercise and 40 g of CHO immediately after each exercise session. The remainder of the SUPP groups daily CHO intake came outside of training. The non-supplemented (NONSUPP) group (n=9) consumed an artificially flavored placebo during exercise. The NONSUPP group had the same daily CHO intake as the SUPP group, with the only difference being CHO timing. Dependent variables measured pre-and post-training included back squat and bench press one-repetition maximums, peak oxygen consumption (V̇O2 peak), power output (Wingate test), body composition, fasted glucose, insulin, and testosterone, and gastrointestinal distress (GID) during exercise. Both groups significantly improved back squat and bench press strength, biceps thickness, absolute and relative V̇O2 peak, and power output. Respiratory exchange ratio was significantly lower and time to exhaustion significantly increased during the post V̇O2 peak test. However, there were no changes in resting glucose, insulin, and testosterone or body fat. RT and HIIT caused significant increases in GID, independent of beverage content, with no differences between training. Our results suggest that CHO timing has no impact on adaptations to exercise training, but favorable training adaptations can be made while consuming a LCHF diet.