2.2. Alternate Day Fasting-Low Carbohydrate (ADF-LC) Diet Protocol

The trial consisted of a 1-month baseline period followed by a 6-month ADF-LC intervention period. During the baseline period, subjects continued their regular diet and exercise routines and were asked to remain weight stable. As such, each subject acted as their own control. The 6-month ADF-LC intervention period was divided into a 3-month weight-loss period followed by a 3-month weight maintenance period. The ADF intervention consisted of feast day alternated with a fast day. The macronutrient composition of the diet was as follows: 30% carbohydrates, 35% protein, and 35% fat. Participants were provided with low carbohydrate meal replacement shakes during both the weight loss and weight maintenance periods (each packet: 200 kcal, 10 g carbohydrates, 26 g protein, 6 g fat; Optifast HP Shake Mix, Nestle, Bridgewater, NJ, USA). The fast/feast days began at midnight each day.

On the fast day during the weight loss period, participants consumed 3 meal replacements per day (providing a total of 600 kcal). Subjects were not permitted to consume anything else on the fast day except for water, black coffee, and tea (without milk or sugar). On alternating feast days, subjects consumed 5 meal replacements that provided a total of 1000 kcal. After all the shakes were consumed on the feast day, participants were permitted ad libitum intake of low carbohydrate/high protein foods. Participants received dietary counseling from the study dietician to learn how to select low carbohydrate/high protein foods on the feast day to comply with their diet prescription.

On the fast day during the weight maintenance period, subjects continued to consume 3 meal replacements per day (providing 600 kcal). Subjects were not permitted to consume anything else on the fast day except for water, black coffee, and tea (without milk or sugar). On alternating feast days during the maintenance period, subjects consumed 3 meal replacements that provided a total of 600 kcal. After all the shakes were consumed on the feast day, participants were permitted ad libitum intake of low carbohydrate/high protein foods.