It depends on your goals and preferences. Some weight training will be beneficial in any regimen as it'll help you build lean muscle mass, increase the amount of calories you burn daily, and aiding in body fat management. However, the total number of weight training days can be altered between 2-6 depending on what form of exercise you actually enjoy doing.
For even more impressive effects on body composition: aim for exercise forms which elicit a positive hormonal response. This means lifting really heavy things (strength training), or interval training. Such exercise increases levels of the sex hormone testosterone (primarily in men) as well as growth hormone. Not only do greater levels of these hormones increase your muscle mass, but they also decrease your visceral fat (belly fat) in the long term.
"When we’re lacking in sleep, our body’s hormones get thrown off balance which can impact our hunger levels the next day. We all have two hormones that affect our appetite: ghrelin and leptin. When we don’t get enough sleep, our ghrelin levels (the hormone that makes us feel hungry) rise, and our leptin levels (the hormone that makes us feel full) drop. This means that when we’re awake, we tend to eat more but feel less satisfied. Try going to bed a little earlier than usual to avoid this imbalance and remember to remove any distractions that might prevent you from nodding off."