Normal or alarming?

[F0GGYCAT]

Dd 16 has lost 6kg in two months. I found a weight chart she's been putting her weight on.secret scales under her bed and a tape measure
She will only eat certain foods and I don't think she has lunch. She won't let us in the kitchen when she's making breakfast so I don't know what she's eating.
What do I do? Go to gp, get counselling? Or shrug off as normal teen behaviour and hope it goes away?
Please help, I'm so upset

That is a lot in a short space of time.

What was her weight like before?

GP, sounds worrying.

Hope you manage to get the right help for her.

It says she was 50kg and now 44kg

I want to go and talk to her and ask if she's happy to go to gp but I keep crying and need to be strong for the conversation

It's hard to say without more context. What did she weigh at the start. Someone who is a couple of stone heavier than they should be then 6kg in 2 months is fine. Someone who was already ideal weight or underweight would be a cause for concern. When you say she won't let you in when she's making breakfast, how does that even work? Does she eat an evening meal with you, does she participate in family meals our etc. I would be concerned about her being secretive over the breakfast but would look to open a conversation with her about why that is and how she is feeling.

Look on here for advice and support
https://www.beateatingdisorders.org.uk/
Good luck OP

Can't eat out anymore. It used to be fine then she started insisting on seeing the menu before we went and usually declined.
Eats dinner with us now but didn't for a while, only eats with us if it is early enough and what she wants to eat.
She was perfectly healthy weight before.

Sorry, cross posted. 44kg is under 7 stone so unless she is very short ie under 5 foot then underweight.
Rather than jump straight into the conversation with talk of the GP start by just talking to her get a feel of how she is. Then move the conversation on to perhaps getting some help. If you go straight in with telling her she needs to go to the GP you are likely to just alienate her. Help her understand that you have her back and that she can trust you to help her in whatever way she needs.

She's 5'4 I checked BMI calculation and it said 3rd centile. Healthy but almost not. I think the fact that she's lost so much so quickly is worrying. She looks thin

Thank you that sounds sensible

Thank you I think I'll call them and ask what to do