That’s not how that works. All animals store excess calories as fat. All of them. Period. Breaking down the organic compounds that store calories (whether from food you just ate or from stored fat) does create heat as a byproduct of the chemical reaction, which is part of how mammal/bird metabolism helps maintain homeostasis and why we require a lot more calories than reptiles or fish, but there is not an animal on earth that doesn’t store excess calories. If you eat more than your TDEE, you will gain weight. If you work out that weight may be muscle. If you don’t work out that weight is definitely fat. If you want to eat as much as you want, you will have to up your TDEE with exercise to compensate or you’ll get fat. And depending on your activity level you can bump your TDEE up by more than a thousand calories. He’s an extreme example, but Michael Phelps was famously eating 10k calories a day when training for the olympics. If he weren’t doing any exercise at all his calorie needs would be closer to 2500.  Also, tip for everyone with regards to health pseudoscience: apply the trait/method/adaptation/whatever to a hunter gatherer group 60,000 years ago. Would they survive with this adaptation? If not, it’s a pretty safe bet that health tip isn’t real. For this, “you convert all excess calories either to heat or fat,” the heat group starves to death after two lean seasons because they don’t have energy reserves to fall back on.                   1000