system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: ELI5: when people from warm climates have extra low tolerances for cold weather, is there an physical cause for their sensitivity, or is it psychological?
gpt
It's a physiological cause.

There are hormones created in the thyroid gland that activate genes that code enzymes that are involved in glycolysis and ATP production. This effect is called the **calorigenic effect**; the cell consumes more energy and generates more heat. For example, children who are born in colder climates produce more hormones (thyroid stimulating hormones; TSH) to adapt to the cold climates. The same response happens to children who are born in warmer climates. This response cannot occur in adults.