So you're overweight or fat. You want to get in better shape,"tone", or fit into a smaller pair of jeans, but how? There is a lot of bullshit out there, which aims to make a quick buck off your ignorance. So here is a short, basic guide to improving your situation and work towards weight loss. If you are in decent shape and wants abs or to "tone", or some such, then you'll need to read the next entry. This guide will mainly serve people who are significantly overweight.
Now your aim should be to lose fat, not weight per se. If you lose muscle, that isn't helpful. If you lose water weight, that isn't helpful. Thus it is important to have a educated diet in order to maximise fat loss, while not at the expense of muscle or anything else. You can go on some liquid vegetable diet for a week and lose 5 pounds. But some of that will be muscle, some of that will be water weight, and you may just put back on whatever fat you lose, if you go back to your old eating habits. It is extremely important to realise that this shouldn't be a temporary diet change. This should be a permanent lifestyle change, which also means it must be reasonable and sustainable.