Should I be concerned that my 4yo has lost weight?

[Drummingisfun]

My 4yo DS has always been skinny. He never had a chubby stage as a baby.
He eats three good meals a day and has a varied diet, he eats most things. Everything we eat is home cooked totally from scratch, except the one meal a week that the kids eat fish fingers.

However, tonight in the bath he seemed more ribby than usual so we weighed him. He has lost 1.5kg since we last weighed him around the end of July (for car seat purposes). According to the nhs calculator he is on the 4th centile which they class as normal weight, but only just.

Should I be worried that he's lost weight? If it was my other DC (who is a little plump) I'd assume it was puppyfat dropping off, but DS doesn't seem to have any spare weight to lose.

1.5kg seems a huge amount for a four year old to lose in two months.
My children only seem to gain 1-2kg in an entire year so I'd be a bit concerned at this.

There's lots of useful tips and valid points out forward by other posters, but I'd be visiting the GP to get it checked out.

Ditch the school lunches even if free - had the same happen with my 4th child and basically just wasn’t eating enough calories during day -did check with doctor first to make sure no underlying problem.

Definitely go see a doctor about this. Sudden and unexpected weightloss is worrying.

Both weights were done naked after bathtime on hard bathroom floor. Digital scales, they seem accurate.

I think I'll try adding some calories and keep weighing and book in with gp in half term if he's not gone back up.
Don't think diabetes is likely. Not more thirsty or going to toilet more.

In nursery he had packed lunch and he didn't ever finish that so I'm not sure I'd get any more calories in that way.

That's a lot of weight loss. I would see a GP.

My daughter lost a lot of weight and I put it down to growing taller. She then became very ill very quickly and shortly after she was diagnosed type 1 diabetic.
Please pop to the docs to be on the safe side.