When it comes to losing weight in increasingly obese America, there are any number of diet pills, weight loss powders and workout DVDs to choose from. An estimated 24,900 businesses are competing for a piece of the $61 billion weight-loss market, all promising to be the magic cure-all overweight Americans are seeking. But its Weight Watchers, the housewife-founded company that uses a simple points system to promote less eating and more moving, that's seeing the most success.