The Effect of Time Restricted Feeding on Fat Mass in Overweight Women

Overview

Participants will complete a one-month intervention where they are will restrict their daily food intake to an 8-hour time period, i.e., between 1200 to 2000 hours. During the remaining 16-hour intermittent fasting period (2000 to 1200 hours) participants will be allowed to drink zero calorie beverages (diet soda pop, black coffee, tea, water, etc) in order to maintain normal hydration. There will be no attempt to restrict food intake. Rather simply to restrict the time period each day when food is consumed. Participants' body mass, fat mass, and non-fat mass will be monitored non-invasively using a weigh scale and densitometry via air displacement (Bod Pod) at 0, 2 and 4 weeks following the dietary intervention. Also, participants will be interviewed following the final body composition measure to assess whether or not they continued to follow the intermittent fasting approach.

Participants (16 overweight women, BMI (Body mass index) ˃25, ages 18- 30 y)will complete a one-month intervention where they will restrict their daily food intake to an 8-hour time period, i.e., between 1200 to 2000 hours. During the remaining 16-hour intermittent fasting period (2000 to 1200 hours) participants will be allowed to drink zero calorie beverages (diet soda pop, black coffee, tea, water, etc) in order to maintain normal hydration. There will be no attempt to restrict food intake. Rather simply to restrict the time period each day when food is consumed. Participants' fat mass will be monitored non-invasively using densitometry (with a Bod Pod) prior to and following a 4 week intervention where the participants will eat their normal daily intake during an 8-hour period each day (1200 to 2000 hours). The Bod Pod measures body volume via air displacement and together with an accurate measure of body mass enables body density to be calculated (Density = mass/volume). Satisfaction, hunger, and fullness with the diet will be monitored on a weekly basis using a validated visual analog scale (Flit et al, 2000). Adherence to the diet will also be assessed on a weekly basis as the number of days the diet was followed. During the 16-hour fasting period participants will be able to drink as much of zero calorie beverages as they desire. On day 2, 7, 14, 21, \& 28 participants will return to the lab at 8am (following a 12 hour fasting period) and both the acidity of their urine (using a urine dip stick) and their blood sugar (using a glucometer) will be tested. Following one month the participants will be allowed either to continue this eating pattern or revert to their prior 3 meal intake. After a month of self-regulation, the participants' fat mass will be measured again using the Bod Pod.