Of course "a calorie is a calorie". That is how the unit is defined. Nobody is disputing the laws of thermodynamics. That doesn't mean each calorie in what we

Of course "a calorie is a calorie". That is how the unit is defined. Nobody is disputing the laws of thermodynamics. That doesn't mean each calorie in what we call 'food' is as accessible to the body's metabolic processes as a calorie in other food. If i wrap a pellet of food inside a non-digestible shell, it will still burn in a bomb calorimeter or will still have about the same caloric measurement in constituent macro-analysis. This doesn't mean calories are a useless model of energy uptake from foods, just that they are not perfect. We also have to take into account that the food industry has not been exactly neutral with regards to this metric. If calorie counting is a thing, then they will game the imperfectness of the metric in any way possible to get the desired 'low' score on the label while still maximizing your addictive consumption cravings regardless of how fat it will or will not make you. So we can/could expect the 'calorie' as a unit of measure to become less and less acurate as a result of this gamign of the metric. But, again, this still doesn't mean that there is no relation between food intake, energy expenditure and weight gain as some would like to portray. If your consumption pattern is making you fat, reducing consumption while changing nothing about the diet composition or timing (yes, when and how you consume also has an influence on your metabolism) will still make you gain less weight or even make you lose weight depending on the ratio change. The reason that previous obvious statement is still vilified is that there is an enormous industry around consumption and managing consumption. It is not by coincidence that the advice from last century about consumption moderation 'eat less' has largely been replaced by an 'eat different' message. Finally, there is an enormous hypocrisy in creating a 'market' system that evolves through rewards the most ferocious and amoral predators that can push whatever 'food' optimized for maximal consumption addiction, and then turning around to the 'consumer' and proclaiming 'personal responsibility' and 'moderation'.