Doctor's Orders: Simplicity
Except after workouts, an athlete should minimize calorie consumption from simple carbohydrates (sugar). Simple carbs can be rapidly absorbed, especially in liquids with little to no fat, or solid foods that lack fat to slow down digestion. Significant quantities of simple carbs provide the release of insulin, desirable after a workout, but not at other times because it can encourage the body to store sugars as body fat. Foods that are high in sugar are among the worst for trainees seeking to keep body fat low.
The one exception here is the extreme hardgainer, like some teenagers who burn so many calories each day that they find it hard to eat enough food. In this case, eating some faster-digeting carbs like white bread and sugars may be a good idea for two main reasons: The first is that these foods digest rapidly. This allows you to be a hungry again much sooner so you can eat more calories. The second reason has to do with the insulin spike you get from fast-digesting carbs. Yes, insulin can speed up fat gain, but it's also a powerful anabolic hormone that pushes muscle growth forward. So, spiking it throughout the day can keep you very anabolic. For those who have no worry about fat gain, this can be a good strategy to build more muscle mass.
Remember that every rest day should be an active rest day. Rest days are for recovery; they're not an excuse to be lazy. Get out and hit 15-30 minutes of HIIT cardio today, or perform 30-60 minutes of your favorite activity: hiking, biking, walking, playing a sport, etc.