Big bones?
There's wide spread talk especially in the weight loss field that humans have varying bone mass, with some being "big boned". Is there any truth in that, since I've read that the bone mass is usually ~20 pounds, which doesn't seem like much that can vary to make people heavy, unless it's common with people to have, say, 200% bone mass compared to the usual. :-/ Often, these people refer to "big bones run in my family". Can anyone with medical knowledge confirm or deny the "big bones" thing? It would be nice to have the total bone mass in this article, possibly along with mentioning this topic. -- Jugalator 08:41, Feb 1, 2005 (UTC)
I don't believe the "big boned" expression actually stems from medical facts. It's use seems to pre-date the invention of the medical technology to measure bone mass. I'm sure you've noticed that some people have larger frames than others. Assume you have two males of the same height, but their chest size differs by 6-8". While the one with the larger torso appears larger/fatter, it's entirely possible that his rib cage is visible through the skin, while the narrower male has a an inch or more of fat covering his. I believe it's from something like this that the big boned expression came to be. In any event, you're interested in hard data & facts, not my conjectures. According to IRPA, bone accounts for 5kg (11lbs) in the 70kg Reference Male and 3.778kg (~8lbs) in the 60kg Reference Female. There is also a link between Body Mass Index and Bone Mineral Content. The Total Body Bone Mineral Content for thin, normal, overweight and obese was 2.2, 2.4, 2.8 and 3.1 kg, respectively. (I'm aware that this clashes with IRPA's Reference Female, but I'm just repeating data.) It does appear that obese people have greater bone mineral content, but this doesn't contribute significantly to the overall weight, nor should it be considered a reason for being classified overweight. In other words, the direction of the correlation is questionable. Perhaps when one becomes overweight, the bones grow simply because there is an excess of nutrients or to accomodate the larger burden being handled by the body. I suspect that if any of the obese subjects lost weight, they would also lose some bone mineral content (but that's just my opinion). I've seen a few notes of bone density being affected by leptin, but some studies show a negative effect, while some show a positive. As far as I'm concerned, there is no consensus on the relation between leptin and bone density. I haven't looked for anything about bone mass that is 200% of the average, but even if it's the case, that would be at most 20 lbs, hardly enough to contribute to obesity (unless the person was extremely short). I hope this helps. --jag123 10:06, 1 Feb 2005 (UTC)
- IRPA Reference Man: http://www.irpa.net/irpa10/cdrom/00602.pdf
- Bone mass, bone metabolism, Gonadal status and body mass index (Pubmed: 12086348)
- I'm in a biomaterials grad course at the moment, and bones do indeed strengthen in response to stress, and weaken in the absence of stress. This is most apparent in cosmonauts (astronauts don't tend to stay up as long), but can also be seen when implants shield a bone from stress and prevent it from healing, or apply concentrated stress and promote uneven bone thickening. I hear some of the best experiments have been from birds with their wings tied back.
- I think "big boned" is a classic case of metonymy, with bones standing for muscles and other connective tissue (pretty heavy, all told) as well as themselves. The English language doesn't predate surgical & anatomical knowledge, much less this particular expression, and agricultural types know more about (farm animal) anatomy & physiology than most folks in cities, but that wouldn't stop them from using a figure of speech now and then.--Joel 01:14, 13 May 2005 (UTC)