Because they did not actually eat that much, and they moved a lot more, and lived in colder buildings, meaning they burned more calories.
Your metabolism is fine.
Seriously. If you put humans in a controlled context and actually weigh their food, the metabolic differences between them are minor, and easily outdieted. Their weight gain and loss is predictable. There are literally no adult humans that can eat only 500 calories a day and gain fat (toddlers already need more); practically no humans that can eat 1000 calories a day and gain weight (this can happen, but you would have a severe, apparent medical condition causing significant other issues); and only few adult humans that do not lose weight at 1500 (that one you can pull of as a small, sedentary, older female). They cannot magically acquire energy out of thin air.
Underweight people overreport their food intake. Overweight people underreport it. Any study working on self-reports is absolute garbage. Any historical comparison based on self-reports is garbage.
Where people measured, the results became very consistent. There are horrid examples of this. Germans tracked how much food they gave Jewish prisoners, and when they would stop working, and when they would starve to death, to get optimum value out of the horror they inflicted. The results were horrific, but not at all surprising or strange, but rather, very consistent. The jews were starved; they became normal weight, while their metabolism barely slowed; then under weight, and their metabolism slowed significantly, with visible massive health consequences, yet still unable to outweigh the dieting; then they died.
On the other hand, you can take your skinny fit European, and put them in a US community where they can’t walk, can’t cycle, and keep being offered giant portions of highly caloric food, and the same person with the same genes and same willpower and same baseline metabolism will gain weight, at the speed you would expect for the extra calories they consume and the reduction in calories they burn.
Well-being and health wise:
If you have a population whose diet is obviously nutrient deprived and high glycemic index, check their body height, their average age of death, their teeth, and their cognition. You will find that they do not do optimally. I think some people just lack a frame of reference for how they would feel if they ate well.
Weight wise:
Because they did not actually eat that much, and they moved a lot more, and lived in colder buildings, meaning they burned more calories.
Your metabolism is fine.
Seriously. If you put humans in a controlled context and actually weigh their food, the metabolic differences between them are minor, and easily outdieted. Their weight gain and loss is predictable. There are literally no adult humans that can eat only 500 calories a day and gain fat (toddlers already need more); practically no humans that can eat 1000 calories a day and gain weight (this can happen, but you would have a severe, apparent medical condition causing significant other issues); and only few adult humans that do not lose weight at 1500 (that one you can pull of as a small, sedentary, older female). They cannot magically acquire energy out of thin air.
Underweight people overreport their food intake. Overweight people underreport it. Any study working on self-reports is absolute garbage. Any historical comparison based on self-reports is garbage.
Where people measured, the results became very consistent. There are horrid examples of this. Germans tracked how much food they gave Jewish prisoners, and when they would stop working, and when they would starve to death, to get optimum value out of the horror they inflicted. The results were horrific, but not at all surprising or strange, but rather, very consistent. The jews were starved; they became normal weight, while their metabolism barely slowed; then under weight, and their metabolism slowed significantly, with visible massive health consequences, yet still unable to outweigh the dieting; then they died.
On the other hand, you can take your skinny fit European, and put them in a US community where they can’t walk, can’t cycle, and keep being offered giant portions of highly caloric food, and the same person with the same genes and same willpower and same baseline metabolism will gain weight, at the speed you would expect for the extra calories they consume and the reduction in calories they burn.
Well-being and health wise:
If you have a population whose diet is obviously nutrient deprived and high glycemic index, check their body height, their average age of death, their teeth, and their cognition. You will find that they do not do optimally. I think some people just lack a frame of reference for how they would feel if they ate well.