may actually be safer when it comes to maintaining adequate calcium levels. First let's look at some recent information with regards to weight loss surgery:
Weight loss surgery can be an effective tool to help obese individuals lose weight.
Weight loss surgery may reduce the heightened health risks associated with excess weight
Weight loss surgery may cause deficiences of calcium and vitamin D absorption.
In fact, studies show that those who lost the most weight with the surgery, also lost the most bone density. This may be due to the loss of gastrointestinal area (and gut absorption) that occurs with the surgery. So doctors and surgeons and other health professionals who care for these patients, need to really stay on top of recommendations for calcium and vitamin D supplements. These patients may even need slightly higher doses - and further research will shed light on this.
On the other hand, though I am not fond of "very low calorie diets," unless they are medically necessary, a new study of young dieters who calorie restricted (on average below 1000 calories) while still "eating a balanced nutritious diet" appeared to lose weight and fat without compromising their bone density. We do know that serious calorie restriction can decrease the rate of biological aging and increase longevity. Still, chronic energy deficiency (which is what these severe diets create) impairs mineral uptake and is associated with weight loss and bone loss.
The researchers concluded that because most people stay on these diets for very short periods of time - the impact on bone density is small, if at all. They were quick to point out that if the severe dieting is chronic or long term, impact on bone density might be more substantial. Personally, I didn't notice if any observations were made regarding whther these calorie restrictors also exercised alot. To me that's typically what serious dieters do - they attack on all fronts - serious calorie restriction AND obsessive or excessive exercising - so I would have like to have seen some mention of whether bone bearing exercise helped to maintain the bone density.
A word to the wise - cutting calories, plus making sure you eat from all the food groups plus exercising is what gets the weight off AND keeps it off.