No, it's not all about calories in/calories out.
I use this analogy. You have an electric car. You put a 2-gallon can of gas in the back seat. Does the car burn the gas? No. When the car runs out of electric fuel, does it burn the gas? No. The car demands more electricity instead, and the gas stays in the back seat.
Our bodies are the same way. If your genes are adapted to sugar burning, then excess energy stays in your back seat

as fat. Even if you burn ALL your sugar by restricting your calories, your body STILL doesn't burn the fat. Instead, it demands more sugar.* Because you're a sugar burner, your body essentially can't see the fat -- exactly like the electric car that doesn't see the can of gas. Your body can sort of burn the fat, but it's very hard and it takes a long time. By that time, you eat another sugar meal and your body gloms onto the sugar and forgets about the fat. That's why it's so hard to lose fat.
But if you ditch the sugar -- entirely, mind you, no half-measures -- your body protests for a couple weeks (carb flu) and then your genes adapt to burning fat. THAT'S when the calorie restriction will kick in and do its magic. If you restrict your fat calories -- easy to do because fat makes you feel full -- then when your body runs out of fat fuel, it DOES see the fat sitting around your middle and in your back seat

, and body says, "Hey lookie, I know what THAT is! I can burn that while I'm waiting for the next fat meal."
That's the weight loss aspect of Primal Blueprint in a nutshell. There are other health benefits but that's a separate topic.
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*it also doesn't help that our main source of sugar, wheat, is a mildly addictive drug. So not only does your body want wheat sugar to burn as fuel, it wants a LOT of it for the addcitve aspect. That's why it's so hard to restrict calories.