To think the NHS BMI calculator is dangerous

[Hyggemama]

Posting this as a friend of mine is currently dieting. They've always shown (in my eyes) disordered eating habits, obsessing over what to eat/ not to eat for "health", juice diets, fasting, vegan, carb free etc. They have always been slim and told me proudly now they weigh 53kg. She's 5ft 5in. I was horrified as she's so skinny now, size 6, ribs all showing, but wants to lose more weight for health. She has told me about studies suggesting the lowest BMI in the healthy range is best for avoiding chronic illness. So I checked what would still be "healthy" and according to the BMI tool she could go to 50kg and still consider herself healthy AIBU to think this is dangerous misinformation to spread from the NHS? Also how do I get through to her that skinny does not = healthy? Anyone got any studies to back me up (she loves a bit of scientific research )

Her friend is not currently underweight, is showing no signs of disordered eating, other than losing weight intentionally and successfully, and is dong something about her pre-existing (presumably before weigh loss) raised osteoporosis risk. She does not yet feel strong, but is working towards it. All that sounds absolutely fine.

I decided to lose weight at 50. And revised mymtarget weight downwards as new shape appearered. Lots of people thought I looked too thin initially, but a few years on and they're all used to it. BMI similar to OP's friend. I'm also fitter (took up running) but my upper body strength is dire, despite a strength/resistance class most weeks.

So I could be the person the thread is about. And it's not inevitable that someone in these circumstances has an eating disorder.

Well clearly it depends on frame. I have a small frame, I'm right at the low end of BMI but, while slim, and not skinny and def have some spare fat on me here and there. In my case I would be rather plump even at he middle end of the range.

So obviously it varies from person to person, hence being a range, and should be interpreted accordingly.

Lots of people thought I looked too thin initially

I will never understand why expressing this opinion is acceptable. I fantasise about saying 'oooh, you're looking so chubby, are you ok?' to people have commented on me looking thin.

The lowest BMI in the healthy range is NOT optimal for avoiding chronic illness on a population level, particularly as we get older. I am a public health researcher and psychologist specialising in eating and weight disorders including obesity. Note I say: on a population level. Individual variation is unavoidable, by definition. If her GP hasn't picked up on the eating pathology, encouraging your friend to seek support from somewhere like Beat (eating disorders charity) would be advisable if you feel genuinely concerned about her wellbeing.

Ah yes, the batshit eating disordered comments are here as usual.
Your friend has an eating disorder OP, focus on that, I'm sure you are but support her.

But i dont think its a diagnosable eating disorder, but a disordered approach to food. Surely as a friend and she has chosen to discuss it with me I have a right to share my opinions. She certainly does on what she thinks is healthy and I want her to be healthy mentally and physically too. Why "stay out of it" when you have an open and honest friendship?

The 'healthy' BMI range is vast. At my height it's about 13kg. I've been towards both ends of it, and look and feel best in the lower middle (am more towards the higher end now, while still 'healthy' and not evidently overweight, but wanting to drop a few kilos). It's a blunt instrument, not the holy grail. It suggests tendencies and provides certain cut-off points to aid medical decisions.

Sounds like she's interpreting the research and the calculator wrong rather than them advising wrong.

Yup. And she’d do that with any information, I guess. Not sure what to suggest op.

She has controlled her food for all her adult life, in a variety of ways... idk maybe I'm too relaxed about food. I've never said to her she's too skinny and never would. Agree that its just as offensive as saying someone's too chubby.

Surely as a friend and she has chosen to discuss it with me I have a right to share my opinions.

Well, you can read up on eating disorders (disordered eating) and follow the advice on how to most constructively help someone suffering with one. Or you can just wang off your opinions.

One way suggests you are a friend who actially cares about their friend's health and not just someone who enjoys to have a view, but it really is up to you. Getting her to fixate on body fat percentage as well as BMI certainly would be a novel approach to the situation.

The BMI calculator isn't perfect but it is a relatively useful guide. Also, nowhere on the NHS website can I see anything that recommends you should aim to be at the bottom of the 'healthy' weight range. Your friend clearly has issues with food and weight and will latch on to anything as an excuse to eat less at this point.

You are not equipped to 'cure' her of this and no amount of articles you send her will change her mind. If she wants to starve herself, she will starve herself and find justification for that somewhere or other. You say she 'loves a bit of scientific research' but in fact, she only love scientific research that she feels backs up her desire to be thin, so it is a waste of time sending her stuff at this point.

I would also add that you absolutely cannot tell how healthy your friend is just from looking at her.

It is not pointless! It doesn't work for everyone though. When I was marathon training I was extremely tiny but still a healthy BMI. I was a size 4 but weight was was OK. The reality was that I was lean and even though I looked 45kg I was really 52-54kg because of my muscle. (My fat % was 14-16% which for what I was attempting was fairly on point). Almost two years later I'm 32 weeks pregnant. I started this pregnancy within a healthy weight (according to BMI) and it has been a breeze in comparison to when I was overweight. No swollen ankles/feet, no water retention, no high blood pressure.

She got food poisoning and the doctor weighed her and said "ah she's fine, she's just marginally under weight bordering on healthy". I couldn't believe it. Fortunately it was short lived and she put on weight and got to a healthy weight, very quickly, but I was appalled at the doctors attitude.

But the doctor was quite right! She was just marginally under a healthy weight as a result of food poisoning & soon put it back on - what else did you expect?

The NHS BMI calculator is a range for healthy. I could be a stone heavier and a stone lighter and still be healthy. What you consider looks 'good' is an entirely different matter.

@Elieza thanks for your advice. Yes a nutritionist or something similar I bet she would love.
@Croquembou the focus is on health for her not looks and she has been denied for donating blood and getting weaker so I feel like yes it is impacting her health. You reckon (as she seems to obsess regardless) aiming for a bodyfat of 20%-30% would be less healthy than 18.5-20 BMI, her current goal?
Like has been pointed out i can't "cure" her if there is anything to cure but surely an awareness of how low her bodyfat is and the implications with health is important

My main concern is what the NHS calculator considers to be inactive/moderately active/active. The idea that between 30-60 minutes per WEEK is ‘moderately active’ and ‘active’ is 60-150 minutes is an absolute joke. No wonder we have an obesity crisis!

Hilariously when I was 21 I was weighed by my GP (I was 13 stones and am 5'9" and was a size 12) normal BP ect he was genuinely shocked "you weigh more than I do!!"

I slimmed down to 11 stones 9lbs when in my mid thirties and looked gaunt

I went to slimming world at 14 stones - now in my 50's but still comfortable in my size 14 jeans..the SW consultant said "are you surprised by this...?" Probably suggesting she was

I was 11 stones at 16 and in my school sports photos looked relatively slim, I had a 28 inch waist!

I have size 8 feet. I have never had a jiggly tummy and my bra size is now 36D having been 36C/B

Fortunately I was brought up with rugby players - many are super fit but are on the BMI obese scale so my mantra is NFR (normal for rugby)

@TinyMystery agree! My friend exercises every day 30mins-1hr so "active" according to NHS would be an understatement. Concerning that 15 mins activity 4 times a week can count as active.

But exercise on its own will never keep the pounds off, it's a mix of both! Running 5k only burns around 250cal... Some people are more responsive to it than others but you need a mix of both. I was able to.lose 4st but I trained 5 days a week on a calorie controlled diet of 1600 per day.

When I met my target weight I was marathon training which meant 12-15 hrs a week of running and strength training. Even then, a "normal" diet of 2000 calories made my weight stable. Didn't really need that much extra.

@Rainbowhairdontcare I agree to some extent but exercise is about so much more than calories burned. It’s about heart health, mental well-being, strength, functional training etc.

I do 1.5-3 hours daily (endurance training) so have to eat about 2500-3000 calories to maintain my weight and it’s great 😂

Exercise is about being fit and improving general health. It's part of the equation, but exercise on its will never solve the obesity epidemic we live in, we need a different attitude towards food IMO.

The problem is a size 6 doesn't mean anything. Some shops cut very generously.

Her eating sounds obsessive, I'll give you that, but the NHS BMI is a good tool for measure body weight.

@thecatsthecats I remember having a new patient medical check in my early 30s. I confused the nurse doing the check as once she started taking my blood pressure and heart rate she realised I was very muscly not fat, so she asked me what and how much exercise I did.

OP as your friend has an eating disorder you won't be able to get through to her being extremely skinny isn't healthy. Instead you can change the subject when she talks about doing a particular diet, not refer to certain food as "treats" (to be fair never heard that term until I came to this site) and you can only confront her stereotypes about women's bodies. For example if you see any sports women/women doing activities like running or cycling comment positively on their bodies especially if they don't fit the skinny stereotype.

reckon (as she seems to obsess regardless) aiming for a bodyfat of 20%-30% would be less healthy than 18.5-20 BMI, her current goal?

I dont think you have anywhere near enough understanding of either eating disorders OR healthy weight and fitness and nutrition to even think of intervening with your friend here.

FWIW my body fat is between 18-20% and that is healthy for a lean athletic woman.
30% bf would be dangerously fatty. I think you should stay well out of it and leave your friend alone.

I agree about the advice re exercise on the NHS website. That should probably be increased.
Unfortunately, a small minority of people would interpret that to increase their exercise levels to another, more extreme level, when they're already doing a lot. That's because some people with eating disorders use exercise as one of their tools.
My own feeling about NHS advice is that it's got to be targeted at the majority of the population, and not the small minority with eating disorders. They've already addressed the issue of BMI not being the only health marker by advising on waist measurement and exercise, and a healthy diet.

Is she just over 8 stone at 5ft5. It is not to bad.
The fact she wants to loose more and is slightly obsessed is worrying, is she attention seeking.
Unfortunately she wont get real help at that weight, after I had DD I lost weight I was just over 7stone, I felt like bones at 5ft 3. When I went for my health check the nurse said your weight is perfect nice and healthy.
I am around 7stone 10, I've still a meaty bum qqit is healthy for my frame.