Modified Atkins diet modifies cardiopulmonary exercise characteristics and promotes hyperventilation in healthy subjects

Abstract

• 4-week low-carbohydrate diet modifies exercise response, lactate and ammonia status. • 4-week low-carbohydrate diet reduces mechanical efficiency in exercise. • 4-week low-carbohydrate diet increases ventilation at rest and during exercise. • 4-week low-carbohydrate diet can potentially promote hyperventilation. Low-carbohydrate diets, including the modified Atkins diet (mAD), are commonly used to promote weight loss, improve exercise performance, and treat refractory epilepsy and inherited metabolism disorders. However, the effects of the high-fat-low-carbohydrate diet on the physiology of healthy subjects still need further study. We evaluated the physiological influence of mAD on cardiopulmonary exercise results in healthy adult subjects. Ten healthy volunteers followed mAD for four weeks with laboratory follow-up. Cardiopulmonary exercise tests were performed before, and at the end of mAD, and venous lactate, ammonia, and blood gases were collected before, during, and after exercise testing. Four-week mAD decreased the subjects’ mechanical efficiency in the cardiopulmonary exercise test and caused increased ventilation and decreased fraction of expired CO2 in maximal exercise. This evidence suggests that mAD can cause hyperventilation tendency at least in the short term, a possible adverse effect of the diet.