The purpose of this pilot study is to find out what eating meals in a short time period early in the day (time-restricted feeding) versus eating meals spread out during the day (grazing) does to the body's ability to control blood sugar and to the health of its blood vessels.

The investigators hypothesize that time-restricted feeding will be more effective at improving glucose tolerance and vascular condition (inflammation and micro- and macro-vascular function) than grazing.

Each participant will eat according to one of the two eating schedules (grazing or time-restricted feeding) for 5 weeks, have a 7-week washout period, and then eat according to the other eating schedule for 5 weeks. Measurements of glucose homeostasis and vascular condition will be performed before and after a participant follows each eating schedule.

Inclusion Criteria:

• Are male
• Overweight: Have a body mass index between 25 and 50 kg/m^2 inclusive (a number calculated from height and weight)
• Are 35-70 years of age
• Have a hemoglobin A1C between 5.5 - 6.4% or prior medical indication of prediabetes
• Have a blood sugar level between 140 and 199 mg/dL two hours after drinking a sugary solution (OGTT)
• Have been eating dinner at least 8.5 hours after eating breakfast at least 90% of the time during the past year
• Have not fasted (go for a day without any food) more than 12 days total during the past year
• Be willing to eat most meals at Pennington Biomedical and/or under supervision
• Not eat any food other than that served by Pennington Biomedical
• Not drink any alcohol, juice, or other beverages that have calories other than what is served by Pennington Biomedical
• Keep water and no-calorie drinks like tea or diet soda the same during both of the timed eating periods
• Be willing to eat your meals according to the fixed schedules

Exclusion Criteria:

• Have diabetes or are on anti-diabetes medication
• Have evidence of cardiovascular disease
• Suffer from significant cardiovascular, renal (kidney), cardiac (heart), liver, lung or nervous system disease
• Evidence of significant gastrointestinal issues or surgery that impacts nutrient absorption
• Regularly use medications such as steroids, beta blockers, and adrenergic-stimulating agents
• Are on any regular medicine that has not had the same dose for 1 month or longer
• Have a clinically significant abnormality as measured by a blood test
• Regularly drink alcohol (more than 2 servings per day)
• Have to do any kind of heavy physical activity
• Currently perform overnight shift work more than one day a week
• Are not able to eat only the food served to you by Pennington Biomedical, while in the study
• Are not able to stop drinking alcohol or other drinks with calories (e.g., soda, juice) other than what is served to you by Pennington Biomedical, while in the study