How can i lose weight without having to stop playing tennis and starving myself?

Balance: Rule of thumb is to change slowly and to maintain a regimen that you know you can maintain lifetime. Therefore, do not skip meals, do not starve yourself, do not stop playing tennis if this is what you enjoy. Keep track of your total daily calories intake and keep track of how much you expend. If you expend more calories than you take in, you should be able to lose weight. Good luck.

Nutrient dense foods: Eat foods that are nutrient dense (like meat, fish, poultry, eggs, cheese, low starch vegatables and water) avoid foods that are not nutrient dense (like starches and sugars, including fruit) nutrient dense foods will increase your basal metabolic rate. On the other hand, starches and sugars impair thyroid metabolism via affects on your liver (which helps activate thyroid hormone).