There is no shortage of health conditions that are either directly or indirectly related to excess body fat. Thus, it is of particular interest, when researchers find conditions for which the risk may actually be lower in obese individuals.
One such condition is hip fractures.
Thus, a meta-analysis by Tang and colleagues from Shanghai, published in PLoS One, demonstrates a substantially lower risk of hip fractures in individuals who are overweight and obese.
These findings were supported by an analysis of 15 prospective cohort studies involving over 3,000,000 participants.
Overall, adults with obesity had a 35% lower risk of sustaining hip fractures compared to normal weight individuals.
While obesity may well be a protective factor for hip fractures, unfortunately, obesity remains a significant risk factor for joint problems in both hips and knees.
So this finding may not be quite enough to write home about.
We now know that for many conditions like diabetes and heart disease, increased fat deposits inside your abdomen and in organs like the liver, heart or skeletal muscle are the real problem.
In contrast, there is increasing evidence that fat deposits under the skin (particularly on hips and thighs) may actually reduce the risk of these conditions.
Simply put, it appears that there is good and bad fat – which is why obesity is not all the same and BMI alone is not a good measure of health.
It now seems that the same ying-yang of visceral and subcutaneous (sc) fat may also apply to the relationship between obesity and bone health.
This notion is supported by data just published in the Journal of Clinical Endocrinology and Metabolism by Vicente Gilsanz and colleagues from the University of Southern California, Los Angeles, USA.
Gilsanz and colleagues studied the relationship between sc and visceral adiposity and the cross-sectional dimensions and other characteristics of the femur (thigh bone) in 100 healthy women between 15 to 25 years.
After multiple adjustments for leg length and thigh musculature, both sc and visceral fat had strong and independent associations with femoral cross-sectional area, cortical bone area, and various other measures – but in opposite directions!
Whereas sc fat had a strong positive relationship to all femoral bone characteristics, visceral fat had a strong negative effects on these parameters – or in other words – sc fat good, visceral fat bad.
Although the authors can only speculate on the reasons for this paradoxical relationship between fat depots and bone health, the data clearly suggests that as for diabetes and heart disease, when it comes to the relationship between fat and bone health, the old real estate mantra applies: location, location, location.