I've read that ultimately the idea is to keep your body mass index (BMI) between 18 and 25. Otherwise you will have a higher risk of obesity-related illness. For example, some people feel perfectly fine if they are 30 pounds overweight. It doesn't affect how they feel, or look, or inhibit their daily lifestyle in any way. However, their doctor might tell them that their blood pressure is a bit high. The doctor might not give an explanation. He might think it is genetic. But even if being a bit overweight doesn't affect you in any other way, the real effects might be too subtle for you to notice without a measuring device, like a blood pressure cuff, or a blood sugar tester.

If you are overweight the best way to reduce your weight is to keep your daily calorie intake at least 500 calories less than your daily calorie expenditure. However calorie intake should never drop below 1800 Calories for men and 1200 Calories for women. That is because your liver, kidneys, heart, an nervous system need this minimum energy to function. People who go on crash diets below this level end up with organ disfunction or even organ failure. So don't do it. If you've reduced your calorie intake to, say, 1800 Cal/day, and you still aren't 500 Calories below your daily expenditure, then you seriously need to get off your butt and do something. Even sedentary individuals will burn at least 2000 Cal/day. On the flipside, it is nearly impossible to lose weight if you don't count calories. People who work out and then buy a cheese burger don't get anywhere because they haven't taken the time and are not explicitly aware of their calorie levels.

Now where you get those calories is another matter. There's each of the food groups that you're supposed to get something from each day. It's for variety, your digestive tract likes variety. It's also for the unique complex carbs, proteins, vitamins, and minerals that those different types of foods provide. Pretty tough though. It takes months, maybe years to get just the right variety of foods. Calorie counting is a piece of cake compared to that.