When baby rats are given too much food right after birth, they develop a problem when they grow up where their brains don't respond properly to leptin, a hormone that controls hunger. This is shown by higher levels of one protein (SOCS3) and lower activity of two other proteins (JAK2 and p-STAT3) in the part of the brain that manages hunger signals.

The study shows that baby rats fed too much (by keeping them in small litters with more milk available) grow up to have problems with leptin signaling in their brains - exactly matching what the claim says. The researchers found higher levels of SOCS3 (which blocks leptin) and lower activity of JAK2 and STAT3 (which normally help leptin work) in the adult rats' brains.