If you’re new, you’ll probably have to start off with just 4-5 times, or even 2-3 times. The first time I did HIIT was after I just recovered from surgery on my left hand (I cut it open real bad, severed two tendons and a nerve). I hadn’t worked out in literally 4 months (the doctors forbade it), but me, being a dumbass, decided “FUCK IT!” and went all out doing HIIT for like 8 cycles. I puked afterwards.
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.
For example, a 200-pound guy following this program would consume 200 grams of protein per day, and eat 2,000–2,200 calories—that’s approximately 420 calories (about 50 grams) from fat, and 880 calories (220 grams) from carbs. Your protein and fat intake will stay relatively constant, but your carbs can be raised or lowered as needed (see Step 5). So, if you’re taking your shirt off on Saturday, begin following this protocol the Saturday prior.
"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."