
Everything 1, 2, & 3 said, plus a few things: 1) Track your calories like your life depends on it. Buy a scale and track to the gram like a schizo coke addict. Track every single thing that goes into your mouth and down your throat, whether it has flavor or not. Read the nutrition facts!!
2) Make sure you don’t decrease your normal activity levels. A trend I think I’ve noticed is that sometimes, people decrease their consumption levels but because of their resulting lower energy levels, they stop doing some of their normal physical activities or stop performing as hard in them. However, that will mean that your maintenance calories will decrease and your weight loss will slow.
3) Take creatine. Creatine is a critical part of the process your body uses to create usable energy for itself, and with your energy levels as low as they will be if you’re in an extreme caloric deficit, you’ll want to have as efficient of an energy production process as you can get.
4) Get plenty of sleep (and rest in general). The body prioritizes usage of fat stores for energy when it is at rest as compared to during more intense activity. So, without adequate rest, your body won’t have enough time to convert your fat stores into energy reserves that you will use the next day.