You are still young, only 14 years old, which is the golden time for physical development. Don't deliberately lose weight, because girls lose weight has many side effects, which are particularly easy to cause endocrine disorders. It is recommended to eat less greasy food, sweets, foreign fast food and carbonated drinks. Exercise more at ordinary times and eat less vegetables and fruits for dinner. Losing weight means not dieting, so you should match your diet reasonably, and you can't eat high-calorie foods and too many carbohydrates.