no such thing....
Dude I honestly hope you don't believe this, trust me humans have very different metabolisms I've seen some extreme cases of individuals with insane metabolisms, for instance my ex gf, she weighed between 95 to 105 our entire relationship (over 1 year), she is a marketing executive who is almost seditary, besides us having sex, she is not active at all, she never even stepped foot in a gym, she had the most caloric diet you could imagine, she would take down insane amounts of food, burgers, fries, pizza, she would drink me under the table, anytime we went out to dinner with other couples people were astounded by the amount of food she took down and how tiny she was, really it was incredible, she would not gain an ounce of fat. I have so many other examples, some of my black friends on the ship, eat absolutely terrible, pancakes with syrup, cheesy eggs, hashbrowns with ketchup, chocolate milk for breakfast, burgers and fries for lunch, candy bars, bags of flaming hot Cheetos, Fried chicken, mac and cheese for dinner, always having sugary juices with every meal, and these guys are absolutely shredded. So I know for a fact not all humans are created equal especially when it comes to metabolism.