this is a fantastic website for weight loss.
I lost 20lbs the first time (after DS1) and almost 30lbs now after DS2.
The principal is that you keep an online food diary. Calories and nutritional value are calculated and you are presented with the facts re. what you eat. You also input your desired weight and it will give you a weight loss calendar, required calories to achieve your goals etc.
I can't recommend it highly enough and it comes with a free trial.