This is a very hard topic to explain. We live in a running world and it can happen that you don’t have time to work out when is the best time to do it. It is very individual, you have moments when you feel in an exploding condition during the day, that moment is the ideal to go to gym and do your workout. There are people who feel this int he morning, and there are who feel it in the evening.
If you want to gain muscle, you will have to train in the morning. There is an excess of male sex hormones in the morning after a 6-7 hours during the night. These are the hormones that make your muscles grow faster. If you want to burn fat, you will have to do your training int he evening. After a hard day, your body gets used to the energy consumption. This way you won’t loose weight from your muscles, because the body burns the fat where is mostly deposited. At man on the abdominal region, and at woman on the gluteal region.