1. Intermittent fasting -- Google it
2. Almost to complete Keto diet--- eat as less carbs as possible
3. ( not necessary but help to maintain muscles ) exercise moderately, HIIT is preferred.
That's all. Fasting and eating less carbs are the keys. I guarantee you will lose some fat, even belly fat by doing this for a month. Actually, this method is not only for losing fat, it helps to control glucose and insulin resistance and to reduce the risks of diabetes and heart disease. It's really a way for better, healthier, and longer life.