I believe you confuse an inequality of Energy(Fat) ≤ Energy(Food) - Energy(Activity) with an equation and are trying to disprove it with a counter-example. Peop

I believe you confuse an inequality of Energy(Fat) ≤ Energy(Food) - Energy(Activity) with an equation and are trying to disprove it with a counter-example. People saying "calories in, calories out" don't help with this confusion too. Another variant of your argument is "but different people extract different amounts of energy from the same food so there!". This being an equality, both arguments make no sense. I give you more - the "Energy(Food)" is calculated by burning the food in question and measuring the energy produced. It's guaranteed to be more than most humans could extract from the food as most humans excrete more complex chemicals than carbon dioxide and water, which burning food produces. But it does not matter because this is an inequality and not an equation. E.g. in your example the inequality still holds, you allegedly increased the Energy(Food) but the energy stored in fat did not increase, as asserted in the inequality. A counter example to disprove this would be somebody gaining more weight in fat than the weight of fat needed to store energy from consumed food. Of course, this would have been broken pretty fundamental laws of nature and would have caused some kind of revolution in physics.