We're wired (via circadian rhythms/our internal 24-hour clock) to have peak alertness around mid-morning, says Dr. Marks. “Early morning exercise can help boost the morning energy surge, as you will have elevated body temperature and elevated adrenalin levels for several hours after you exercise.” Need an extra incentive? Research has shown that exercising before breakfast burns more fat calories and results in more weight loss than exercising after breakfast, says Burr Leonard, founder of The Bar Method.