"Calories eaten per day" is not a free variable. It's governed by a control loop within the brain. In a healthy person, appetite adjusts to compensate for calorie surplus or deficit. We have an epidemic because that control loop is getting damaged. People have a hard time discussing this because they treat it as a moral issue. But it's clear that recruiting our frontal cortex to count calories should not be necessary -- every mammal needs to automatically maintain homeostasis, and does so just fine in its natural environment.

And "calories burned per lb bodyweight" is also not a simple constant. It has been observed swinging significantly. A starving person's metabolism will slow dramatically to conserve energy. An overfed (healthy) person's metabolism will ramp up and favor burning the excess over storing it.

So of course we can't cheat thermodynamics, and of course eating less matters. But how to eat less is an animal behavioral question, governed by biochemistry.