There is much debate about the ideal time to exercise. Basically any time you can do it, is good. Whether early morning or late evening, the most important point is that you just do it. Continuous cardiovascular exercise sustained for at least 30 minutes, will burn fat no matter when you do it.
BEST TIME TO EXERCISE
An advantage of early morning cardiovascular exercise (whether before or after breakfast) is the “after burn”. After completing early morning cardiovascular workouts, you not only burn fat during the sessions, but also continue to burn fat at an accelerated rate afterwards. This phenomenon occurs because an intense session of cardiovascular exercise can keep your metabolism elevated for hours after the session is over. Completing cardio in the evening will of course burn fat during the session. However, during sleep, your metabolic rate is at it’s lowest of the day and therefore the evening cardio session is unable to take advantage of the “after-burn effect of morning cardio.
However, although controversial it some argue that for maximum fat burning, early morning cardiovascular exercise before breakfast, is best. Carbohydrates (glycogen) are your body’s primary and preferred energy source. When your primary fuel source is in short supply, it forces your body to utilize its secondary/ reserve energy source - body fat. Nevertheless others argue that the alternative fuel source used by your body may be muscle. However, most evidence is equivocal. You must know your own body. Do what feels right for you.
EXERCISING BEFORE BREAKFAST FOR WEIGHT LOSS?
Proponents for exercising before breakfast argue that early in the morning before you eat, your levels of glycogen (stored carbohydrates) are low. The time between your last and first meal of the day, tends to be between 10 – 12 hours. During this overnight fast, your glycogen stored slowly decline, because it is being used to keep various bodily functions going while you sleep (heat beating, breathing, etc). Thus, in the morning your glycogen stores are depleted and your blood sugar lower. Since, during cardiovascular exercise your body initially uses its glycogen stores as fuel and only after these are depleted turns to burning fat, this means that the switch from utilizing glycogen to burning fat occurs earlier. These are the ideal conditions for burning fat instead of carbohydrates. It is uncertain how much more fat is burnt, though some studies suggest this figure could be as high as 300% more fat burning.
If you exercise immediately after eating, you’ll still burn fat. However, you may burn less fat, as you’ll be burning off the carbohydrates you just ate. The body always burns a combination of fat and carbohydrates, though depending on when you exercise, you may burn a greater proportion of fat compared to carbohydrate.