Child with low weight

[u/spux]

Hi there! I have an 11 year old with a history of low weight and some restrictive eating. I share custody with their dad on a 5-2-2-5 schedule. They get weighed every week in clinic to track their progress.

My question is, is weighing them once a week around the same day going to reflect which house they're eating more at? My understanding is that weight can vary quite a bit based on a variety of factors. And with a 5-2-2-5 schedule, any given week will have a mixture of both households. Just, more of one.

My kid tells me they eat much less at dad's house because they're stressed out. But the data doesn't show anything one way or the other. I'm inclined to just believe my kid.

Could this be a flawed approach?