That’s true if you’re a bomb calorimeter (a device used to measure the energy [calories] contained in different foodstuffs). But the human machine is a bit more complex. The fact is that we all have individual metabolisms that affect how we use calories, and the end result is that a certain number of calories for one person can mean for another person quite a different thing in terms of body weight.
Which is good fodder to support the idea of mindful eating (intuitive, eating). Our bodies’ appestats are designed to tell us when we need calories, and that’s one of the major premises of mindful eating. That we listen to signals from within to tell us when to eat and when to stop eating.
So next time you see a chart claiming that if we substitute a lower-calorie choice for something we regularly eat, we’ll lose a certain amount of weight, be skeptical. There’s no way that can be accurately predicted outside a metabolic laboratory. (Even then, there may be limitations.)