When is the Best Time to Exercise?
Exercising isn't easy so it's natural that we all want to maximize the amount of calories we burn and while also being able to maximize the effort we put into our workouts. Is the best time in the morning, noon, after work, or before bedtime? Is it before or after a meal? Well, just like so many other things in the fitness field, there is no clear-cut answer.
Working Out Before a Meal
The theory here is that you will be burning more fat stores compared to glycogen stores (glucose in your blood, muscle, and liver). The reason for this is because you haven't eaten for a few hours (at least 8-9 hours if it's before breakfast), so the glycogen stores in your body are low. Therefore, your body will need to obtain energy for the workout from your fat stores, which is ideal if you are trying to lose weight. However, it is harder for your body to break down fat for energy, and you may not have the energy to exercise at as high an intensity. In addition, some people just aren't 'morning' people, which means that, again, the workout will lack intensity and they will be less motivated.
Working Out After a Meal (Including Breakfast)
Assuming you won't eat so much that you feel sluggish, working out after a meal is a reasonable thing to do. The advantage of this is that you will have plenty of energy from the nutrients you just consumed. The disadvantage is that you will not burn up much of your fat stores because your body is getting energy from your recently consumed meal. If you are not trying to lose weight this might be ideal for you as the quality of the workout might be higher.
Working Out Just Before Bedtime
The main advantage of a pre-bedtime workout is that you will be using calories primarily from your recent meal, which means the calories that were consumed will not have the chance to be stored as fat while you sleep while energy requirements are low. The disadvantages may be fatigue from a long day which will affect the workout quality, and some people have trouble relaxing and sleeping after a workout. Of course, some others sleep even better after a good workout.
Morning vs. Evening
Keep in mind that exercise is a form of stress. And a common response to stress is to eat more which is driven by a natural reaction of the body. So, a morning workout may cause you to eat more throughout the day, whereas an evening workout may prevent this because you will be, ideally, be sleeping at the time when the cravings would start.
So, the best answer is; it's so up to you, based on your goals, time schedule, personal motivation, etc. For example, if you want to lose fat, consider exercising before a meal. If you want high intensity workouts then your best bet is likely working out after a meal.
Also consider your energy and motivation levels. For example, if you are highly motivated in the evenings, then make use of that motivation because trying to go against what you 'feel' like doing is bound to decrease motivation and lead to poor quality workouts.