How to lose 4kg in 4 weeks?

Diet, exercise: While not recommended to lose that much weight so fast, it is possible. First, you will lose water weight initially - that will reduce weight significantly. Second, the weight loss rate slows down after that. Exercise at least 5x/week - doesn't have to be aerobic every day. Also, need to reduce your caloric intake by up to 20% for now. Drink lots of water for metabolic processes ; hydration.