a healthy fit male eats 1500 - 1800 cals a day The amount of calories you should eat to lose weight is not the right question. If you do exercise at least 3 times a time for 30m-60m each time, and if you eat heathily (fruit, vegetables, soups, meet, fish, bread, water) you will be fit, healthy, slim. If you are overweight, the first thing to do is to cut on the unhealthy food (muffins, other cakes, sugary meals, salty meals, burgers, pizza, etc) and start to make your diet turn to salads, fruit, vegetables, lots of fluids.