I don't want to lose any more weight, but the app says I need to.

[ThatFraggle]

Because of a family history of diabetes I've been told to keep my BMI under 23. It is 23 right now, and I would need to lose 9lbs - half a stone -4kg - to get there.

It feels like I am too thin at that weight - both in the face and figure (I was that weight after a period of being unwell). I actually prefer how I look at the top end of my BMI. Not quite Nigella, but some curves.

Would it be ridiculous to ignore, and not bother to lose weight and stay at 23.something bmi.

Also, I'm trying to exercise more. As I put on muscle, my weight will increase, but I don't want to go down a dress size. So the BMI won't line up. E.g. muscly me will probably weigh the same as 'pleasantly plump' me, and if I want curves on top of that, it will make me overweight.

Has anyone navigated this before?

You are overthinking this. Your BMI in itself will not help prevent diabetes. Keeping your body fat level in the healthy range will.
BMI is simply a tool to give you a rough idea - the reality is that a lean person with a higher BMI (due to muscle) will have a lower risk of diabetes and other conditions caused by excess body fat than someone who is 'skinny fat' with a lower BMI.
So don't be a slave to BMI!

having big boobs or curvy figure can make a big difference to BMI, meaning some healthy curvy people have an out of whack BMI that doesn't account for their curviness. the system is flawed!

Surely you only need (theoretically) to be a pound under a BMI of 23, to be 'under' 23, why are you saying you need to lose 9lbs?

Is your family heritage from the Indian subcontinent? I think I read that they have to keep their BMI artificially low to lower the risk from diabetes. Not easy

How's your waist measurement? Both in absolute terms and as a proportion of your height and hips. If that's fine or better than fine then you can probably get away with a slightly higher BMI.

And how tall are you? Again taller people are probably OK at a slightly higher BMI than short ones because the power of two in the BMI formula is chosen because it's an reasonable fit and easy to use but it doesn't fit the risk equally well at all points on the curve.

And have you had any blood tests done to assess how your diabetes risk is looking?

I'm short. I don't have a tape measure for my waist. I've had blood tests, nothing amis.

I've got medium boobs.

Get a piece of string. Measure a length as tall as your height. Can you comfortably wrap it twice round your waist?

And get a tape measure, they cost a couple of quid from any supermarket. Or you can get apps to use on your phone apparently though I've got no idea how reliable they'd be on your waist.

like a zillion years ago when I was a member of OverEaters Anonymous, we had a speaker who said she struggled to reach a healthy weight because she wanted big boobs. She wanted to look like Marilyn Monroe. it was a really headache for her to accept that a healthy weight, she did not have big boobs.

But She could & did come to accept her body was meant to be a different shape. It was a process, that took time. I thought she looked great, btw, but I suppose I prefer a lithe look.

You haven't explained why you prefer being plump other than it's what you're used to, or it's a beauty standard you don't want to let go of.

You could save up for boob & bottom implants later, if you find you still can't be happy with that slimmer profile. Guaranteed that your body will change in your life, though, it's not ideal to be very attached to your looks.

Bottom implants are a lot more risky than a BMI of 23 and a bit.

If the OP prefers a fashionably large arse and getting her waist measurement down to a healthy levels compromises that she'd be much better off with padded knickers.