system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do women get intense cravings for certain foods while pregnant?

I am just curious as a friend has a pregnant wife and she’s making him get all sorts of things. The cravings are almost like an addiction withdrawal he says. Why are certain bizarre foods craved as well, like pickles? Do the cravings go away when the baby is born? Thanks in advance!
gpt
There's no hard and fast answer for this - esoteric cravings in the brain still aren't wholly understood. But some scientists guess that as a woman's body exerts itself in the pregnancy process, burning excess calories and fat to help "feed" the baby and change itself to prepare for birth, it manifests any particular deficiency it's experiencing as a craving for a specific food.

If the woman's body is low on sodium she might crave pickles, for example, or if she needs simple fats she might suddenly be hungry for ice cream. It's not a perfect answer - it relies on a rather tenuous connection between unconscious autonomic processes and a specific craving in the brain, as if your body could "remember" which processed foods contain which nutrients it needs at the moment. But it seems to be an explanation that accounts for the observed behavior.