Originally Posted by MaDalton

exactly this.

there are 2 studies - one guy only ate chocolate bars, the other only McDonalds but both stayed below their daily calorie goals and both lost weight

of course carbs, proteins etc also play a role - for example for how long you feel full or whether you need energy for working out.

But basic line it always comes back to intake<usage = weight loss

(there are many fat vegetarians and vegans around)