@PurpCat @david Merely mcdonalds won't be enough, considering you can only eat at mcdonalds and lose weight.

To achieve that, you'd need to constantly eat large amounts of fast food (that is for fasting, not for eating - it can even be non-fast food with enough effort), constantly snack between meals and also (optionally, but it helps a lot) drink a lot of alcohol (beer contains a lot of energy and a 12 pack of a low-alcohol beer won't make a alcoholic blackout drunk, but it will make them fat).