If you're trying to lose body fat, you may not be eating enough. When you do eat clean, you may not be eating enough to satiate yourself or supply your nutritional needs. Clean food is much less calorically dense than crappy food, even though it is more nutrient dense. It is nearly impossible to eat clean 90% of the time if you are not eating enough clean food - under eating leads to cravings, loss of will-power, and hunger. Not that you should over eat either.
What I mean about will-power is that if you pit your brain against your body in a battle over food, your body will kick the crap out of your will-power every single time. It's like holding your breath - you can do it for a little while, and if you are really diligent you can do it for even longer, but eventually only one of two things will happen:
#1. Your body will take over, black you out and start making you breath because it thinks you're an idiot, depriving it of it's much needed air (just like your body really needs it's nutrients).
#2. With long enough deprivation, you will cave into the cravings of your body, and take huge breaths of air involuntarily (this is just like the cravings that ultimately break everyone's diet). People used to eating small quantities of crappy food that is loaded with calories, switch to healthy food and end up starving their asses off and get really hungry and find that they can never eat "right." Little do they know that if they ate enough of the right stuff at the right time, then they would have a much easier time with self-discipline - when you a well sated you don't really crave the junk.
Clean food would be fruits, veggies, lean meats, eggs, reduced fat dairy products, healthy fats/nuts/seeds, and a limited amount of whole grains. With an emphasis on WHOLE: "Whole wheat flour" is an oxymoron, if I was whole it would still be a whole wheat berry, not brown powder. Crappy foods would be Danishes, bagels, muffins, French-fries, cookies, regular soda...
CASE STUDY
My fat-loss clients come to me having no idea how much clean food they should actually be eating. Case in-point: There is a 160lb active woman that I work with for fat-loss and all she eats in a day is this:
#1. 2/3 cup FAGE yogurt + berries (1 cup - strawberries) + 1/3 cup granola [225]
#2. Turkey wrap same as below - [408]
#3. Lean Cuisine - [250]
#4. 2/3 cup FAGE yogurt + 1 cup berries [135]
Total kcal - 1,018
Her problem with compliance is just that she doesn't eat enough.
Here's what she should be eating in a given day for rapid fat-loss (10 x body-weight is a pretty aggressive diet). Less than this would probably result in an inability to stick to a meal plan 90% of the time (which was a problem with the ridiculously low 1,000 kcal/day), and a slowing of her metabolic rate. Both of which add up very slow progress.
1,600 kcal Clean Food:
1. 1 piece of fruit + 2 hard-boiled egg whites + 1 slice cheese [230 kcal]
2. 1 cup strawberries (50) + 1 cup 1% cottage cheese (163) [213 kcal] 3. 1 south beach meal [260 to 300]
4. Wrap: turkey lunch meat 4oz. + 1 wrap + veggies + mustard + 1/4 cup cranberry sauce - jellied (it's nutritional crap, but she really likes it) [408]
Let me remind you that this is what a 160lb woman should eat on a DIET, not maintenance. You'd be damn full and would have a hard time thinking about even eating the other stuff. Yes it will still take some will power to keep your eating at 90% or better, but now it's actually possible because you are working with your body, not against it - cravings are a powerful force.
