However, excercise does have other effects, possibly including reducing cravings and changing hormone levels and maybe (over the long term) gene expression.
Of course proper diet does have a huge effect in weight loss though.
I can and have lost eight pounds (not water) in three days. I could do it right now. I call BS on whatever research.
A pound of fat is roughly 3500 calories. In order to lose eight pounds of fat in three days, you would have had to induce a caloric deficit of over 9000 calories per day.
A note to everyone: The most weight you can healthily lose is about two pounds per week. More than that and you're going to start losing a measurable amount of muscle mass. The exception is when you first start out exercising and eating properly, but that should only last for a couple of weeks.
I specifically said it was not water.
In other words, sorry if you don't believe me, but much of what you lost was water.