BMI and Health

sheldonklein

Yesterday I met a renowned cardiac rehabilitation doctor - really a big shot in his field. He told me, in substance, that the best research shows that BMI has an essentially U shaped risk curve, with bad outcomes associated with BMIs below 18 our above 35, and relatively small differences within those boundaries. I'm someone who has lost 60 plus pounds to move from Class II obese to overweight and am questioning whether I want to lose another 30ish to get to a normal BMI. I'm a58 yo with no aspirations to be a competitive athlete or have the body of a Greek god. So, what is the evidence re the shape of the risk curve? Are there strong health reasons to get from a29 to a 24BMI?

palwithme

That is a great question. I don't know the answer but have been wondering the same thing myself.

sheldonklein

I'm one of those annoying people who like to answer their own question, so here's a study that concludes (i think) that there are no significant health differences between normal and overweight BMIs.http://www.nature.com/ijo/journal/v31/n1/full/0803365a.html

If I'm misreading or ignoring other conflicting evidence, I'm eager to learn.

fraseria

I'd disregard BMI completely, as I am doing actually... I have no idea what the risk curve looks like for BMI and its going to be difficult to say. A study to determine that is going to have to take too many variables like pre-existing conditions and genetic predisposition into account. My main problem with BMI is that it doesn't take frame or muscle mass into account, and in my opinion is a bit of a gross over generalisation. So essentially it can tell a healthy short and muscular guy he's overweight, while it can tell a taller overweight guy he's actually in the ideal range or close to it.

Personal opinion - Body fat % is a bit more accurate picture of what's going on in your body. So measure that and aim for somewhere in your age appropriate range, and then its pretty much up to you whether you want to aim for the ideal or average range. Ideal for age 56 and up is between 19.1 - 25.9 and average 26-30.8. Considering your goals, I'd just aim for anything below "above average". I'm pretty sure the health risks will be at a relative minimum as long as its below the 30.8% mark and above 19.1%.

r5d5

Well, typically, the concern with being overweight/obese is because of the body fat you carry which can be detrimental to joints, bone health, cardiovascular health, respiratory, digestion, diabetes... There are also huge risks involved with visceral fat, which is fat that gets stored in and among the inner cavities, so around your organs. That obviously is very dangerous. Overweight and obese individuals are more likely to carry visceral fat, while less overweight, or "normal weight range" individuals tend to carry subcutaneous fat, which is fat stored just under the skin. It carries less immediate health risks.

Of course, this is your personal decision to decide what to do, I don't mean to push you one way or the other, just trying to answer your question!
I wish you all the best, and encourage you to look into it more to decide what you want.
(And yes, perfectly acceptable to not look like a greek god, but not everyone in the normal BMI range does look like a greek god. Believe me, I wish it were merely that easy!!)

Robertus

Our bodies have evolved to carry some fat during times of famine, during the winter months, etc, so people that are a little overweight (by BMI standards) have been more likely to survive and reproduce. But not so fat as to no longer be fast enough to hunt effectively or run from a saber tooth tiger. You only have to outrun the fatter members of the clan. This is not fashionable so most people want to be super lean and we are conditioned to find that attractive. In the Western world, with supermarkets and restaurants aplenty, we no longer have to worry about times of famine or food shortages in Winter months so there is no downside to being more fit and there are advantages, both in terms of attracting mates and in terms of being able to perform better in sports and other strenuous activities. It is very enjoyable to be fit and in good condition. Attaining the level of fitness that you desire and enjoy is much more important than a number on a scale.

MoiAussi93

There is no definitive answer to this available at this point. I have read things that seem to indicate that being slightly overweight might not be harmful to health...and might even be protective in older people. The key being slightly...being truly obese seems to be dangerous based on everything I have read.

I also think where you carry the excess weight matters. Abdominal fat is very dangerous. All doctors and researchers seem to agree on that point. That's why the waist circumference measures are so important if you are in that overweight but not obese category.

Exercise also seems to play a factor...the "fat but fit" thing we see so much written about.

Sorry, but the true answer is that there isn't a simple yes or no answer for this question. Science just hasn't found a clear answer yet, so you have to weigh all the various factors and come up with a target whose risk level you are comfortable with.