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Why weight loss leads to bone loss in some women.

April 17, 2015

Dr. Fox responds to the following article:

http://www.reuters.com/article/2015/04/15/us-weight-loss-bone-loss-idUSKBN0N624L20150415

It is well known that with starvation diets (low calorie), that 50% of the weight loss is lean body mass composed of bone and muscle as opposed to fat. With regain of weight after such a loss, the vast majority is fat. Therefore, yo-yo dieters continue to add to their fat % with each cycle of dieting. This is most likely due to the stress response of the body and production of cortisol, the stress hormone. Cortisol makes humans more insulin resistant, so when calories reappear, the body puts on more fat. Makes sense because nature would want the individual to add more fat stores to survive the next starvation interval. Sadly, the vast majority of proposed diets in the US are starvation diets. Even in this study all the diets were “low calorie,” without a representative ultra low carbohydrate high fat diet that would be calorie neutral or high calorie. Researcher’s don’t even think about it so why should our population. It’s no wonder our population is sinking into a nutritional abyss!

As to why the bone loss. From our perspective, the estrogen levels in these premenopausal women drop in response to stress. “Nutritional Stress” is one of the stressors we talk about in the group of stress factors facing our women today. Lower estrogen results in less bone production and faster loss depending on the age of the woman. We see in men the opposite problem that may account for the “paradoxical” increase in bone seen in the male subjects of the study. In men, the more fat the more testosterone is converted to estrogen. Estrogen in males feeds back to the brain to turn off testosterone production and thus decreasing fertility, a phenomenon that we often see in our patients. The estrogen however is positive for bone and therefore maintains or increases the bone density accounting for the findings. It’s just physiology. Men also seem to be more resilient to stress from a hormonal standpoint.

In LCHF (low car high fat) weight loss the lean body mass is maintained and in our experience even for the yo-yo situation, there is not so much overshoot in the cycles which likely comes from the absence in cortisol and the stress response in the LCHF patients. As we recommend, in this approach, calories are not to be cut and in fact for most would increase relieving any stress on the metabolic system.
Michael Fox, MD
Gainesville Office: Jacksonville Center for Reproductive Medicine
Jacksonville Center for Reproductive Medicine
Advanced Reproductive Specialists of Orlando
jcrm.org

   
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