Why do some need to eat lower on the calorie density chart?

[a-great-hunger]

We all know those people who can eat high calorie density foods and stay trim. Others eat very low on the calorie density scale to maintain their healthy weight. Still others use little tricks, like time-restricted feeding, to keep the pounds off. Outside of highly active people, why are some people predisposed to weight gain without a very low calorie density diet?

Why, I wonder, is this?

[f1jim]

I suggest some of this is genetic. We know there are genetic traits that enhance keeping weight on so the body can survive famine.
f1jim

[VeggieSue]

Outside of highly active people, why are some people predisposed to weight gain without a very low calorie density diet?

Why, I wonder, is this?

Dr McDougall discusses this in his book The McDougall Program for Maximum Weight Loss. There are many factors, including sex, age, hormone status, etc. The book explains it all, and more, so why not give it a read.

[Drew_ab]

We all know those people who can eat high calorie density foods and stay trim. Others eat very low on the calorie density scale to maintain their healthy weight. Still others use little tricks, like time-restricted feeding, to keep the pounds off. Outside of highly active people, why are some people predisposed to weight gain without a very low calorie density diet?

Why, I wonder, is this?

My initial reaction is to say that like anything there is always a bell curve. Most people fall within the normal range but there are always outliers either way. The number of possible factors here is that could contribute to someone being at either end of the curve is virtually limitless. Some people engage in high levels of NEAT (non-exercise activity thermogenesis), some people have high level of brown-adipose tissue, some people spend time in cooler environments and literally neat the body to produce more heat, some people have a more active thyroid gland, some people naturally produce more (or less) testosterone/estrogen, some people have genetic variants that affect metabolism, some people's biochemistry has been affected by infections/pathogens/viruses in a manner than alters metabolic rate, some people have taken medications that have altered their microbiome (i.e. anti-biotics) that alter their need for calories in positive/negative ways, and on...

While I really do feel that the list of possible answers is massive, it is still a fun question to entertain nonetheless.

[Matcha]