Drinking several cups of unsweetened instant coffee a day won't make you fat, but only if it's instant pure black coffee and not instant 3+2 coffee.

Instant black coffee diet:

Black coffee has very little calories, a 100 grams of black coffee has only 2.55 kilojoules of calories. Drinking a cup of black coffee after a meal can effectively break down fat. In addition, black coffee is more diuretic. For women, black coffee also has a beauty effect. In the process of boiling coffee at high temperatures, an antioxidant compound is produced, which helps fight cancer, anti-aging, and even has the effect of preventing cardiovascular disease, comparable to fruits and vegetables. Note that pure coffee without mate, milk or sugar is black coffee.

Pure caffeine can directly burn fat, drink coffee with some exercise, can play a very good effect, but caffeine will affect sleep, so it is best not to drink after 8 pm.