Do not exercise on an empty stomach in the morning. I don't know where you heard the method! I am engaged in fitness work and have a certain understanding of slimming. Don't be on an empty stomach, it's bad for the gastrointestinal tract. If you want to lose weight within a month (I don't know if you are a man or a woman), as long as you can keep doing aerobic exercise for more than an hour every day, 20 kg in February is no problem. The effect of exercise in the first month is not obvious because exercise is accumulated day by day.

You can ask questions again. I am willing to answer patiently!