No. Mine are completely fit and muscular. Most animals who are free fed manage their weight better than animals who have a set feeding schedule. (Ironically)
This may or may not be true, but based on my own observation with my personal colony. I want to say that the extra stuff in the 6f makes the males eat less. I rarely see mine eat compared to the females who are always chowing down. Plus the males aren't using as much energy(unless he's breeding) to want to refuel.
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