According to current research, all of us are correct as to the best time of day to exercise. It is whatever time is best for us. If the only time you have is first thing in the morning, that is the best. On the other hand, if you can only do it right before bed, then that is best.
That being said, the absolute best time to exercise is the time you have each day available for exercise consistently. For instance, if you set 20 minutes aside in the morning but keep skipping it, then it is not the best time for you so you should look at changing the time to one that works better. On the other hand, if you consistently workout right after work everyday, then that is the absolute best time for you.
Research indicates it is when someone exercises constantly that is what causes weight loss and fitness over time. In addition, research shows that your body adapts to exercising at a specific time when you do it repeatedly however, there are both advantages and disadvantages to exercising in the morning or evening.
There are some advantages to working out in the morning as proven by research. When you work out in the morning, you tend to be more consistent because you have fewer excuses not to do it since you haven't had all day for excuses to pile up. In addition, working out in the morning can help you become more alert at that time of day and more tired at night when you go to bed. Furthermore, it helps you sleep better at night since you are tired. While you sleep, the sleep helps improve muscle growth.
Another advantage is that your body tends to burn more calories when you haven't eaten in a while and are in a "fasting" state. This is because your body is burning your stored fat rather than the food you just ate to fuel your exercising. There is also research indicating that burning stored fat causes a longer burning of calories. In addition, morning exercise leaves you with increased energy levels, better alertness, more focus, and better decision making.
On the other hand, if you don't have enough fuel, you'll drag a bit and this is caused when you don't eat enough the night before. A way around this is to eat a small snack before working out. You also might interrupt a deep sleep and you'll feel groggy when you get up. In addition, it may take you a while to get warmed up and you may not feel coordinated right away.
When you exercise in the afternoon and evening, many people perform better because they are functioning better later in the day. It has been found that muscle strength, flexibility, endurance, and power output are higher in the evening. Furthermore, it takes longer for people to to reach the point of exhaustion. Since your core is warmer later in the day, it is easier for people to get warmed up and into the workout.
In addition, when you workout later in the day, the exercise is better at relieving stress. The increased endorphins are great for getting rid of stress and leaving you feeling great for helping you wind down at night. Exercising in the evening can also replace bad habits such as eating, drinking, or smoking so you are healthier.
Unfortunately, if you exercise too late, it can interfere with your sleep, making it harder to get a good nights sleep. Furthermore, it can be more difficult to exercise constantly in the evening due to your social life, or because you are just tired after a long day. Don't be afraid to try different times to see which works best for you. Let me know what you think, I'd love to hear. Have a great day.