Grizz -
Losing weight always boils down to taking in less than you burn. Just conservation of energy, plain old physics tells us that. And 25 years ago, that's all we thought was going on....skinny people don't eat too much, fat people do. But we're finding that it isn't quite that simple.
Now, there are MANY people in the US whose primary problem is that they eat more than they should; and MANY of those don't think they take in as many calories as they do. For those folks, well, it's time to cut out the appetizers, reduce calorie containing drinks, and have smaller servings.
But - There are clear cut genetic influences here, so some folks find it far easier to gain weight than others. I see a number of people who genuinely are taking average to below average calories and still find it hard to lose weight. I've had some who are obese despite taking in 1200 - 1400 calories per day, and some who swear they can't lose weight despite carefully counting out 1000 calories daily.
Remember that the system is designed to avoid starvation, and that up until the last 20 -30 years most of us couldn't afford supersized servings. So when the body sees extra calories, it wants to hold on to them in case there's a famine this winter. And once it has the extra fat, it wants to keep it "just in case."
We are just beginning to understand an entire system of weight and metabolism control hormones that center on the gut, rather being triggered from the brain. Grehlin and Leptin are two of these, and the experts are just beginning to work out how they interact with appetite, "weight set points", and metabolism.
So anyway, the equation "weight change = (calories in - calories burned) x (a constant)" is true - but not the same constant for everyone.