Wait, does that mean I can lose weight by not sleeping? How am I still fat?
Sleeping is important. It is king. Diet is queen.
Whether you want to lose weight or gain, put sleep before all else.
To lose weight stick with about 8 hours.
If you are really putting on weight in a proper manner and you are still in puberty < ~23 years of age for males, then 12 hours is going to be the norm. You will have to sleep that much with the quality of exertion and amount food required to gain weight.
When I went bonkers, I nearly slept weekends away. That was the only time in my life I wasn't an insomniac, till I started get my sleeping sickness from being at the parish.