It's best not to drink too much Pu 'er and black coffee a day, because both contain caffeine and are prone to insomnia. If you really drink too much, drink about two sips of low-alcohol red wine or skim pure milk before going to bed at night.

I suggest you do it at noon. Black coffee can be boiled with an apple or banana or melon slices in salt water.

I suggest you make a plan and implement it step by step. For example, you can focus on eating apples or black coffee for the first three days, then change to normal lunch, black coffee and apples for the next seven days, drink plenty of water for dinner, and eat some cherry tomatoes if you are really hungry.

In the next few days, you can change breakfast to normal and lunch to half, such as a small amount of vegetables and starch.

Pay attention to nutrition. You can add some simple exercises later. It's winter. If it's not a tall building, you can run or jump rope and squat and stand up and sit-ups. If you are not afraid of the cold, you can play badminton outdoors.