Yep... Diet is far and away the most important factor. Even how much you eat is more important than what you eat. A person can live on 1200 or so calories a day, easily. It may not be the calories you want, but you won't starve.
Portion control was my biggest hurdle.
Yeah, mine too. Somehow, a steak the size of a deck of playing cards isn't quite enough for me. That's what I call a good start, NOT a complete meal.