Calories in - Calories out is so simplistic as to be useless. I mean yes technically, it is true, however it doesn't factor in your metabolism, how you feel, WHAT that weight loss is made of (fat, muscle, organs?), micronutrient content of food, whether the exercise is actually damaging you, etc. 1000 calories from a shrimp and cauliflower curry cooked in coconut oil runs much different than 1000 calories from McDonalds fries with ketchup and a shake.
Yeah, scientists, way smarter than any of us, figured out a while back that the laws of thermo applies to all living creatures.
Nutrient Utilization in Humans: Metabolism Pathways
Rubner's observations proved that, for a resting animal, heat production was equivalent to heat elimination, confirming that the law of conservation of energy, implied in Lavoisier's early experiments, was applicable to living organisms as well.
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