An interesting question:

I've read the most important thing to look at when trying to lose weight is CALORIES. However, you can be on or under your calorie intake, but still be over, say, you sugar, fat, or carb intake, sometimes by a lot. So then what? If you're under the "biggie" (your calories), and thus, ok, but over other categories, does that mean you'll lose or gain weight? I've been on target or under my calorie allowance but over one or two others. So does that mean I won't lose weight?