guinea pigs

That sounds reasonable. My little lady is almost 4 years and 850 g. Her cagemate is a younger and much less active gentleman who has developed an excess of chonk at 1110 g.

She was heavier and had some thyroid issues that caused weight loss but she’s stabilized now. My advice is to do weekly weigh-ins. If she’s stable, it should be ok.

If you notice she seems to be always ravenous and/or moody, that’s how we first picked up on the thyroid issue, coupled with a noticeable weight loss (as in feeling different when picking her up, not even needing a scale).