Changes in subjective measures of appetite during 6 months of alternate day fasting with a low carbohydrate diet.

OBJECTIVE: Alternate day fasting (ADF) has been shown to lower body weight and improve subjective appetite by increasing fullness. What remains unknown, however, is whether carbohydrate restriction during ADF would provide additional weight loss benefits by helping to lower hunger as well. Accordingly, this study examined the effect of 6-months of ADF combined with a low carbohydrate diet on fasting and postprandial appetite ratings. METHODS: Adults with obesity (n = 31) participated in ADF (600 kcal "fast day" alternated with an ad libitum "feast day") with a low-carbohydrate background diet (30% carbohydrates, 35% protein, and 35% fat). The 6-month trial consisted of a 3-month weight loss period followed by a 3-month weight maintenance period. RESULTS: After 6-months of an ADF-low carbohydrate diet, body weight decreased (P < 0.01) by 6.2 ± 1.0 kg, relative to baseline. Subjective hunger and fullness did not change throughout the study. Fasting insulin decreased (P < 0.05) by 3.3 ± 1.3 µlU/mL by month 6, relative to baseline. Fasting glucose and insulin resistance, remained unchanged over the course of the study. Hunger and fullness were not related to body weight, glucoregulatory factors or energy intake. CONCLUSIONS: These findings suggest that ADF combined with a low carbohydrate diet is not associated with any changes in appetite, relative to baseline. TRIAL REGISTRATION: Clinicaltrials.gov, NCT03528317.