Obesity(bariatric) surgery

Sorry, I have been thinking further. Just because there is a link between a medical condition and BMI when looking across whole populations does not mean that that risk applies when you apply that statistic to individuals. Because if a third of BMI measurements overestimate what weight group you fall into and a third underestimate they cancel each other out but the fact remains that two thirds of individual calculations are wrong.

This means that one third of people will be told that they are in the low risk zone for these medical conditions when they are actually in a high risk zone and should be taking action while another third will be told that they are at high risk when in fact they are in a lower risk zone and they may be put at risk of developing medical conditions like osteoporosis which are associated with low weights.

BMI is an economic statistic not a medical statistic and should only be used to calculate population averages, and not applied to individuals.

If it isn't as a measure of body fat what is it? It is currently used to provide an index on the basis of which it is decided whether a person is underweight, normal weight, over-weight or obese. As far as I know all these descriptions are defined by how much body fat that person has.

Yes, I agree that if your BMI is 30 it doesn't necessarily mean that 30% of your total weight is adipose tissue but if your BMI is 30 you are defined as obese and this is defined as having too much body fat.

Aka you said obesity as measured by BMI is linked to several life threatening conditions.
But the point the various articles make is that although obesity is linked to life-limiting conditions, BMI is not an accurate indicator of that obesity, so how can BMI be an indicator of these conditions?
You appeared to agree with that, with your reference to athletes in your earlier post.

The point is that the NHS is going to offer bariatric surgery to people based on their BMI, when it is not an indicator of morbid obesity for individual patients.

Well after reading all the previous threads I still feel fat!! But take some consolation in the fact that I have exactly the same build as an aunt and my mother so I guess some of it is genetic. My family always call me "big boned" but I am still targeting an upper weight limit so have about 2st to lose.

Thank you Flickety.

However obesity as measured by BMI is linked to several life threatening conditions.

PS

BMI is not, and never has been, intended as a measure of body fat

That's exactly what I've been saying Flick and JaneA that BMI does not measure body fat.

Unfortunately it is very difficult to measure % body fat, though there are a few rough and ready measures out there eg Bioelectrical Impedance (scales very inaccurate), skin calipers (better but rely on experience of user),
Hydrostatic Weighing (but you need to be underwater!) DEXA scan (not just for bones but needs a GP referrel usually) Air-Displacement Plethysmography
(not something found at your local gym) ...therefore only way to measure body fat easily is using a waist:hip ratio or similar.

How accurate it's impossible to tell as not enough research available yet, and it's visceral fat around the organs which is most dangerous and hard to spot.

So I come back to my original point that at least ... we accept that BMIs don't measure body fat, and they are not 100% accurate, but it does give a rough and ready guide for use at home, in the GP surgery or the gym.

Thanks for the links I agree with everything they say!

Currently DDiL has been told that DGD is overweight and DGS is underweight. You only have to see DGD running round in her dancing leotard to see that if she is too fat she is hiding it very well as she is no fatter than her underweight brother.

Look at the build of the two children and the reason for these differing weight results are obvious. DGD inherits her build from our side of the family, DS and DH are both wide in the back, big-bodied and stocky in stature and that is the shape she is as well. DGS inherits his build from his maternal grandfather who was long and lanky with a very slim build and DGS's proportions are almost fairy-like. Both children are very active, get a good diet and eat well. Build plays an important part in comparative weight

rosequartz, some years ago I did an environmental archaeology course and this included a session on osteology and we went to look at two skeletons excavated from a monastery. One of them had tiny birdlike bones and the lecturer said that when they first saw it they thought it was a female skeleton, but a closer examination showed that it was definitely male. Beside it was another skeleton, only a few inches taller and his bones were massive, thick and clearly much heavier. If the two skeletons had been weighed the second would have weighed at least twice as much as the first.

So yes, bone structure makes a difference.

Thanks for the links, FlicketyB

Regarding BMI my son failed his medical to join the army as they said his BMI was to high. He's 5'9" large framed and weighed about 12.5 stn at the time. SiL said he would loose the slight excess during basic training and that he worked with squaddies fatter than that. DS was disappointed at the time. I wasn't!

I was in the right mindset, anneey, for 12 months but seem to have gone off course over the last couple of months.

I had read some articles on BMI and whether being overweight (not obese) was not bad for health. Can't remember where I read it now. I have heard that being overweight rather than underweight would help prevent osteoporosis.

Could it be that some people's bones are heavier than others? I have no idea, but someone may know.

I think the argument about whether there is a link between % body fat and disease is a quite separate argument.

My argument, which has good academic support, is that the BMI does not measure % body fat accurately in the majority of cases.

If you go into the history of the development of the statistic you will find it was never meant to.

Here is one: www.ncbi.nlm.nih.gov/pmc/articles/PMC2877506/ and here is a quote from its conclusions:

'By using BMI as a marker of obesity we misclassify +/-50% of patients with excess body fat as being normal or just overweight and we miss the opportunity to intervene and reduce health risk in such individuals. Conversely BMI may lead to misclassification of persons with normal levels of fat as being overweight, a fact that could cause unnecessary distress and prompt unnecessary and costly interventions. In addition such mislabelling has a deleterious effect on public trust for health care providers, particularly from fit patients with evident preserved muscle mass'

The 50% applies only to those whose BMI under estimates their body fat, no figure is given for those whose BMI is overestimated. If we take that at a conservative 16%, it gives you the two thirds figure I used, I cannot retrieve the source that gave me that original figure

For a more colloquial demolition of the BMI read this article by a member of the Mathematical Association of America web.archive.org/web/20090505180701/http://www.maa.org/devlin/devlin_05_09.html It is entitled 'Do you believe in fairies, unicorns or the BMI?'

Aka I have been unable to find any scholarly articles on the exact percentage error of BMI as an indicator of health, but here is Dr Briffa on the subject.

www.drbriffa.com/2010/04/23/forget-the-bmi-and-concentrate-on-getting-rid-of-your-gut/

Quote: It turned out that about a third of the study subjects, although ‘obese’[according to BMI measurement], did not fulfil the criteria for metabolic syndrome. In broad terms, these people could be described as being ‘metabolically healthy’. In other words, for a significant proportion of the population, being ‘obese’ does not at first sight appear to be such a bad thing in health terms.

I think that without doubt there are psychological reasons behind some people's weight gain, many people comfort eat and reward themselves with food when good things happen as well but when you walk around town and see the groups of overweight young women, all dressed in the height of fashion, regardless of the difference in size between them and the celeb of their choice, it is difficult to believe that the extra weight they carry is not the result of eating too much and the poor quality of their diet.

However dealing with this weight gain in anyway that doesn't also include developing good eating and exercise patterns is avoiding the issue and seeing bariatric surgery as the solution is a cop out. Bariatric surgery is major surgery and as well as operative and immediately post-operative risks that are the same as with any major surgery. In addition a significant proportion of bypass patients have problems with the results and effects of the surgery not working properly. Those receiving the surgery have to face up to the fact that how much they eat and what they eat will be severely restricted for the rest of their lives. They will also need to take medical supplements to ensure they get the balance of vitamins and mineral etc that they need as they will no longer be able to get them through their very limited food intake.

Even then it has been shown that a proportion of those receiving these by passes (not just those with bariatric balloons) still do not lose as much weight as hoped because they subvert the process by finding ways of continuing to eat the same foods that led to weight gain in the first case because they have not had sufficient psychological counselling and support to come to terms with why they had developed these bad eating patterns in the first place.

Bariatric surgery can make many peoples life a misery of not being able to eat normally, needing food to be served in tiny portions and liquidized for perhaps forty or fifty years. Bariatric surgery is not the easy 'Get out of gaol@ card that the NICE recommendation suggests.

You are soo right Rosequartz. It is all about being in the right 'mindset'.
I am there at the moment and I hope it lasts.
I sent a message a few days ago under Health.
I was inspired by my Surgery. Who recommend the Dash Diet. I have ordered the book.
The Scales have come out from under the bed, at long last!

I work hard at keeping my weight at a reasonable level - if I don't I just pile on the pounds - and one of the things that strikes me when I go to the supermarket is how much junk they sell. If you are just buying fruit and veg, a bit of meat and fish, and basics like eggs and milk, you only need to visit a couple of aisles or so. I would guess that at least half of the floor space is devoted to selling manufactured crap. Nothing wrong with the odd treat now and again, but when so much of the stuff is in the shopper's face it makes it very difficult to choose sensibly. I find that by doing my shopping at small supermarkets, where the choice is more restricted, I avoid temptation and save money.

Changing a diet that is really high in fats and carbohydrates (which metabolise into sugars) has to be a big factor. Unless people make these changes, even with surgery it will not help.

Manufactures of the less healthy fast food insist a lack of exercise is the problem in the rise of obesity but portion control would make a big difference.

Stop food outlets selling supersize portions or all you can eat buffets? It's drastic and probably unenforceable but there is no doubt portion size is an issue.

Addiction is possibly a cause, but the nation was not this overweight 30 yrs ago! The changes in food marketing promoting the high fat, high sugar, large portion diets has to have had an effect

There is evidence that really drastic calorie control measures can reduce the chances of and occasionally reverse Type 2 diabetes, but people need to have the motivation to actually change their diets. That seems to be very hard to do.

www.ncl.ac.uk/magres/research/diabetes/reversal.htm

It's a minefield, isn't it? What I do think is dreadful is blaming overweight people for their condition. I don't pretend to understand the many reasons concerning this issue, but I'm sure that poverty, the easy and cheap availability of foods containing unbelievable amounts of sugar, the culinary deskilling of three generations (for various reasons) and the increasing portion sizes served in pubs and restaurants has a lot to do with it.

Anecdotally, there must also be issues from early childhood which play a part. I have a colleague who is obese. She knows she is and is unable to do anything about it. But in conversation, she told me that one of her elder siblings was born with severe handicaps and when she was born she was sent to live with an aunt who had no children of her own. She was a very 'bonny' baby and then when the older sibling died, she returned to her parents. There must have been attachment problems as well as the over feeding and I think that must have contributed to her problem. Of course this not scientific, but I wonder if there are studies which show how early childhood experiences impact on later weight gain.

HI ninathenana I have had a 'weight problem' all my life and struggle endlessly. I did let it rip once and got to over 16 stone - now about 11 and a half and really struggle. I eat healthily, fresh food lots of fruit and veg and play golf three times a week but that's the best I can do. If I just ate and drank what I wanted to I have no doubt I would be gigantic and like before unable to walk far, severe back and knee pain and no doubt my lupus would react strongly too so another high cost NHS patient.

My issue is with fast food - high fat and high sugar. My question is if we don't tackle this is the answer really surgery- leading doctors seem to disagree? My experience in many many slimming clubs is that long time members often talk about 'well if this doesn't work there is always surgery'. My friends son lost 12 stone all by himself through eating properly and cycling. He had surgery to remove the excess skin as you cant do this any other way and his post operative infections were horrendous and life threatening. All bariatric surgery is horrendous but more and more people are asking for it and of course as they have seen in USA its quite possible to eat fast it. I had a friend who had her jaws wired years ago and she used to melt Mars bars in a saucepan and drink them through a straw. There is a lot more talk now about treating overeating as an addiction which I feel might be the way to go.

Been thinking about this some more Flick and I see where we are both coming at it from different assumptions.

To get a BMI you need your height and your weight. This is then used in a calculation to get a ratio of your height to your weight.

But to get a percentage of body fat then you have to go into then you have to go into your body composition which cannot be done by a simple height:weight ratio I agree.

Ideally you need to know % body fat, % muscle, % bone etc.

It's just occurred to me Flck that perhaps you think BMI is a measure of body fat ie if your BMI is 30 then you have 30% body fat or if 18 then your body fat is 18% ... is that how you are interpreting BMI?

It is not that at all just a mathematical RATIO between height and mass.

You keep mentioning body fat. BMIs do NOT a measure body fat. No wonder you think them innacurate. That's like saying you can work out the speed of a car from it's petrol consumption.

Gaga no one ever has to be a victim.

It all sounds so easy doesn't it? Eat less and exercise more. But like many others I have personal experience of dieting strictly and losing a lot of weight, on several occasions and each time as soon as the calorie intake increases, so does the weight.

There must be some people who could only maintain a slender body by eating a very restricted diet and I believe that research is being done on that point I look at my genetic inheritance and can see that my body type is from the thickset heavy side of the family tree. My Dad was a heavy, solid man all his life and lived to 93, only succumbing during an operation on a leg ulcer which had turned gangrenous through neglect by the district nurse. All his side of the family had the same build and unfortunately so do I. However we have strong hearts and live long lives with generally good mental and physical health.

It feels like a witch hunt by the skinnies at present with all the judgemental press coverage and finger pointing. We are not all gluttons with no self-control. Some of us are victims of our heredity.

PS I am a mathematician I have no problem with statistics.