TY - JOUR
T1 - Blood Ketones Are Directly Related to Fatigue and Perceived Effort during Exercise in Overweight Adults Adhering to Low-Carbohydrate Diets for Weight Loss
T2 - A Pilot Study
AU - White, Andrea M.
AU - Johnston, Carol S.
AU - Swan, Pamela D.
AU - Tjonn, Sherrie L.
AU - Sears, Barry
N1 - Funding Information:
This work was supported by a grant from the Inflammation Research Foundation. S.L.T., the research chef, received consulting fees from the Inflammation Research Foundation; B.S. is a stockholder and serves on the boards of directors of Zone Labs Inc and Zone Cuisine Inc; he is also on the boards of directors of Zone Café and ZoneNet.
PY - 2007/10
Y1 - 2007/10
N2 - Ketogenic diets have been associated with reductions in free-living physical activity, a response that can be counterproductive in individuals trying to lose weight. To explore whether popular low-carbohydrate diets might impact the desire to exercise by raising blood ketone concentrations, fatigue and perceived effort during exercise were compared in untrained, overweight adults adhering to a ketogenic low-carbohydrate diet or to a control diet low in carbohydrate, but not ketogenic (5%, 65%, and 30% or 40%, 30%, and 30% of energy from carbohydrate, fat, and protein, respectively). In this prospective, randomized, 2-week pilot study, all meals and snacks were provided to subjects, and energy intake was strictly controlled to provide approximately 70% of that needed for weight maintenance. At baseline and at the end of week 2, exercise testing was conducted in fasting participants. Weight loss and the reductions in fat mass did not differ by group during the trial. At week 2, blood β-hydroxybutyrate concentrations were 3.6-fold greater for the ketogenic vs nonketogenic group (P=0.018) and correlated significantly with perceived exercise effort (r2=0.22, P=0.049). Blood β-hydroxybutyrate was also significantly correlated to feelings of "fatigue" (r=0.458, P=0.049) and to "total mood disturbance" (r=0.551, P=0.015) while exercising. These pilot data indicate that ketogenic, low-carbohydrate diets enhance fatigability and can reduce the desire to exercise in free-living individuals.
AB - Ketogenic diets have been associated with reductions in free-living physical activity, a response that can be counterproductive in individuals trying to lose weight. To explore whether popular low-carbohydrate diets might impact the desire to exercise by raising blood ketone concentrations, fatigue and perceived effort during exercise were compared in untrained, overweight adults adhering to a ketogenic low-carbohydrate diet or to a control diet low in carbohydrate, but not ketogenic (5%, 65%, and 30% or 40%, 30%, and 30% of energy from carbohydrate, fat, and protein, respectively). In this prospective, randomized, 2-week pilot study, all meals and snacks were provided to subjects, and energy intake was strictly controlled to provide approximately 70% of that needed for weight maintenance. At baseline and at the end of week 2, exercise testing was conducted in fasting participants. Weight loss and the reductions in fat mass did not differ by group during the trial. At week 2, blood β-hydroxybutyrate concentrations were 3.6-fold greater for the ketogenic vs nonketogenic group (P=0.018) and correlated significantly with perceived exercise effort (r2=0.22, P=0.049). Blood β-hydroxybutyrate was also significantly correlated to feelings of "fatigue" (r=0.458, P=0.049) and to "total mood disturbance" (r=0.551, P=0.015) while exercising. These pilot data indicate that ketogenic, low-carbohydrate diets enhance fatigability and can reduce the desire to exercise in free-living individuals.
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U2 - 10.1016/j.jada.2007.07.009
DO - 10.1016/j.jada.2007.07.009
M3 - Article
C2 - 17904939
AN - SCOPUS:34648843261
SN - 0002-8223
VL - 107
SP - 1792
EP - 1796
JO - Journal of the American Dietetic Association
JF - Journal of the American Dietetic Association
IS - 10
ER -