At its most basic, weight loss is not a difficult concept. It boils down to burning more calories than you consume. There are many programs that emphasize one side or the other, but it still reduces to that simple formula.
Programs like Weight Watchers and Jenny Craig will try to help you count the calories that you consume. This can be helpful if you are trying to diet and don't know the best foods to eat and how to measure calories through a day or week.
Even programs like the Atkins diet or Hollywood diet are trying to find more enjoyable ways to limit the calories that you consume.
Other people like to focus on exercise to burn off more calories than you consume. So you find a variety of infomercials on TV trying to sell you the latest bike or ball or flexor to burn off calories and turn them into muscle.
All experts would probably agree that a combination of diet and exercise is the healthiest way to promote weight loss. Each body is different and responds to one or the other better.
I would like to add two practical suggestions to the above pattern of diet and exercise. First, as you develop your diet, write down everything that you eat. Along side if the notation of food that you ate, write the approximate calories that it represents. There is something about this hard evidence that helps you realize what is happening. The second suggestion is to vary what you eat and how you exercise. Your body seems to normally try to level out your metabolism. So, when you start eating less, your body will compensate by burning less. When you walk two miles a day to burn calories, your body may compensate by burning less calories. To avoid hitting a wall, or leveling off, vary your intake and vary your exercise. You may be surprised how this will help you continue in the direction you want.

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