I want to lose 40 pounds in 3 weeks. i don't know how to do. please give me your advice and a proper diet to lose weight. thank you?

Low carb diet: Start your day with fresh lemon juice in 6 oz warm water,may add few drops of honey. High protein breakfast- 2 eggs,oat meal,walnuts or pecans,fresh or frozen berries.coffee without sugar &milk. Salad for lunch- extra virgin olive oil,vinegar & pepper. Dinner before 6 PM. Near no carbohydrates.Can have yogurt @ kefir.Lean meat & plenty of fish,non starchy veg & fruits. Walk 30 min daily,try yoga