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 )

I think it's better to trust the NHS rather than just your opinion.

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

The dangerous misinformation is not the information on the NHS site, which shows mainstream BMI calculations (which are of course indicative, nit diagnostic)

It's her utterly misguided belief that the lower end is better regardless of her frame. Perhaps that is what needs to be counter?

Dress size is totally unreliable, as it never r ally recovered from the vanity sizing of the 1990s. A size 6 is toughky the same as an earlier size 10. Which is a perfectly normal size to be.

Obviously skinny doesn't automatically equal good health, otherwise smack heads would be operating at peak fitness. But there's no reason to think the BMI calculator is dangerous.

Because people can hold weights very differently and be healthy or unhealthy depending on ranges. For the average person, which most of us are, it’s a decent guide

But you’ll get lots of larger people come on and tell you it’s nonsense and use the example of Arnie being obese according to BMI as an excuse for ignoring it

I agree with you, when my daughter was about fifteen she shot up and went from a chubby kid to a very skinny teen, she was about 5 foot seven at the time, and weight about 50kgs. 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.

On the flip side, I was also at the doctors, a different doctor, I'm five eight and at that time had got up to eleven stone, and seeing the doctor for an unrelated issue he told me randomly to " get all that excess weight off". I actually sat and stared at him with my mouth open and was speechless for once. As was the female student sitting in his office listening,

Bmi, doctors, sometimes it's all batshit.

I don't think it's dangerous, it's just not the be all and end all of good health.

You can be slightly overweight and healthier than someone whose BMI is "just right" - a lot of it depends on your lifestyle. A slightly overweight person who is extremely active and eats plenty of fresh fruit and veg is going to be healthier than someone with a BMI of 19 who smokes to suppress their appetite and eats one meal a day.

It's an indicator of good/bad health - nothing more.

She should look at the actual data and calculation that sits behind BMI. It’s a population measure tool which is why it has a wide range because it accounts for different builds and muscle mass for your height, and different ethnic backgrounds which affects health risk status and BMI. So yes it’s a useful guide and it is a significant indicator of risk for anyone to move beyond the upper or lower parameters, but it doesn’t tel you much about optimum weight for you within that range. Women should have a body fat percentage between 20-30% which for some people might mean they are ‘healthy’ at 24 BMI and other would need to be more like 20. The only accurate measure is body fat % and percentage of which is visceral fat.

Everything and anything is going to be dangerous to people with distorted eating habits.

You look for conformation. This is at both ends of the scale.

Rather than disprove her. Look for stuff about nutrition, as well as being 'skinny-fat'.

The best thing for everyone is to eat nutritionally well and do strength training.

Women need to guard their bone health, ask her if she's doing that because being frail is one of the most debilitating conditions when aging.

The range in weight is to take into account different builds and body compositions.

At any particular weight, a fine boned person who doesn't exercise could be overweight, whereas a person of the same height and weight with a broader frame and muscular build due to lots of exercise might not be because their body fat percentage will be much lower and it is this what we should concern ourselves with for health, but it isn't as easy to do as stepping on some scales and measuring simple body mass.

SlackerMum1 thats so true. I knew the range was broad because of different builds but didn't know how to phrase it correctly. Completely agree 50kg could be healthy for a 5ft 5 person that has a naturally small build. I guess the problem is with how she is using it rather than the tool itself but to me there should be more info like youve all put it clearly on the website. That your healthiest weight might be different to someone else of the same height, I know it seems like common sense but I think when people are so fixated on controlling their food intake common sense sometimes lapses. I could try encouraging a focus on fat rather than weight... what is a reliable way of measuring body fat? The pinch tests offered at our local gym are apparently not always reliable.

BMI between 20 & 25 is ideal for health.
You can be healthy outside that range, but 20-25 is an ideal.
Article for your friend:
journals.plos.org/plosone/article?id=10.1371/journal.pone.0109153

Bluntness100. If you put those details (owith a guessed date of birth midway), she comes out within the healthy range on the child BMI calculator on the NHS page.

So that might be why the doctor was unconcerned.

It would be just underweight on the adult scale, but that was not appropriate for someone her age.

Ponoka she actually has a history of lots of fractures and brittle bones, in her 50s now and does strength training. But she has said she doesnt feel so strong i guess like you said when you have a disordered mindset anything can be used in the wrong way to support that.

Why don't you just stay out of your friend's weight? If you think she has an eating disorder, this is unhelpful and inappropriate. If you just don't like her being thin, that's none of your business.

If this situation was reversed and you were fussing about your friend being overweight, people would be going mad at you.

I could try encouraging a focus on fat rather than weight... what is a reliable way of measuring body fat?

Mental.

But you’ll get lots of larger people come on and tell you it’s nonsense and use the example of Arnie being obese according to BMI as an excuse for ignoring it

I am larger, and I don't think it's nonsense, but I do think it's simplistic, and because of that simplistic measure of health, it makes itself easy to dismiss, and as in the case of the OP, masks potential problems.

I'm 5'9". When I was 14st (I'm working my way back there...), I had a 28" waist - far less than half my height. Little abdominal fat (ribs showed when I was on the leaner side, visible abs), and large and powerful leg muscles. Huge boobs. The nurse who measure my BMI laughed it off, because my resting heart rate was 55, blood pressure perfect, and measurements small.

I gained weight for various reasons through my twenties, and part of how it got so bad was that my weight and BMI had ALWAYS been poor indicators of my overall health. If I'd been realistic about other measures of health, I might have acted sooner, or put them first.

I'd like to see an understanding of health that went beyond weight, personally. In fact, a far more rounded one altogether, incorporating mental health (which was by far the biggest factor in my weight gain!). A ten point check list for factors that indicate you need to put your health first.

Croquembo - What should the OP do if she is worried about her friend potentially being ill due to being underweight? Your advice to not get involved isn’t helpful when someone is worried and wants to help. I don’t think it’s jealousy that her pal is thin. I think she loves her pal. It’s difficult to know what to do when a friend has an eating disorder and I don’t know what i would do if it was me and my bestie. And that would also apply if my friend was very heavy and it was affecting her health and I was worried about that. I’d want to help her be healthy.

Perhaps a gift of a nutritionist appointment as you know how much she wants to be healthy?... (Ie youre worried sick she doesn’t know what she is doing and a professional may help)? Just be prepared for her to say the person doesn’t know what they are talking about if their advice doesn’t suit her....

Seeing ribs at a healthy weight isn't unusual. From what you are saying, she is undereating and trying to maintain muscle through strength training. In theory, she is doing the right thing but in order for this to work, she needs a diet tailored to this workout - impossible to say whether she has that.

It sounds as if she is very focused on the scale and forgetting that strength training will add weight. Essentially, if you lift, the BMI goes out the window and one should really focus on measurements.

Croquembo - What should the OP do if she is worried about her friend potentially being ill due to being underweight?

She should follow the extensive advice online for helping someone with an eating disorder. It's easily Googleable. And all of it will tell you that engaging someone with an eating disorder on conversations over their weight or eating habits is extremely unhelpful.

YABU. BMI is a good indicator for most of the population. Your friends disordered eating would be fuelled by anything to suit her agenda.

BMI between 20 & 25 is ideal for health.

This is so simplistic though. You can have a BMI of 20 but smoke everyday, do no exercise and live on a diet of plain pasta. Equally you can have a BMI of 27, eat your five a day and do plenty of exercise.

BMI is only one indicator of health.

53kg at her height means she certainly is very slim but not dangerously underweight or even clinically underweight. Her BMI is 19.4, big deal!

I'm 5 ft 8 and weigh 55 kg. I'm a healthy weight. Why do you think you know better than the NHS?

My BMI is in the overweight category.

Im a size 10, my doctor told me not to worry about it as BMI should only be used as an indicator. The extra weight is on my boobs (34F, natural) and not round my waist.