Earlier quoted context omitted.
Sure, but some might be genetically predisposed to make more efficient use of calories (burn easier rather than store as fat). Which could make a massive difference.
If I'm 6'4" and 20 years old, I can probably eat 2500-3000 calories a day and stay slim. If I'm 5'10" and 50 years old, I can probably east about 1900 calories a date a stay slim. It is a huge difference. But, it doesn't matter. Some people can eat more than others and not get fat. There is no justice in the universe ;-). Whether it is some gene, your body size, your age or something else, it doesn't matter. Eat too…
Just invent flying cars, that will solve some problems. Easy, right? The "HOW" is a problem, not "what is needed". When obese people don't eat too much, their body thinks "I don't have enough, time to enter energy saving mode and increase hunger".