Bariatric surgeries are powerful and effective therapeutic approaches to combat obesity and Type 2 Diabetes (T2D). However, a new study concludes that patients will continue to lose bone for at least two years following weight loss surgery even after their overall weight stabilizes. The results come from patients who have undergone gastric bypass surgery, a common weight loss surgery type.

Anatomical changes can put patients at risk for mineral insufficiencies and consequent osteoporosis.[1] The patients are more prone to fall and fractures after bariatric operation. Routine exercise and bariatric-specific vitamins are effective tools to mitigate bone loss in overweight patients undergoing weight loss surgery.

About the Study

On June 30, 2014, the study was presented at the joint meeting of the International Society of Endocrinology and the Endocrine Society: ICE/ENDO 2014 in Chicago, Illinois.

According to the study’s principal investigator Elaine Yu, MD, MSc, an endocrinologist at Massachusetts General Hospital, bone health should be monitored in weight loss patients. The team of researchers once found that patients who had gastric bypass surgery did, in fact, lose bone mineral density, an important factor in bone fragility, just one year following weight loss surgery.

Because the rate of bone loss is so high, the researchers continued to monitor these factors in this study, funded by the National Institutes of Health.

Bone mineral density is typically measured with a standard imaging method called dual-energy x-ray absorptiometry or DXA. However, this method can often give inaccurate results in obese patients. This means that the researchers measured bone density differently using a 3-D type of computed tomography or CT called a complete CT scan.

They compared the bone density at the lower spine and the hip in 50 obese adults – 30 who had surgery and 20 who had lost weight in a non-surgical way. All of these non-surgery patients were similar to the baseline age, body mass index, and sex. After surgery, the surgery patients all received high-dose vitamin D supplements as well as Calcium.

The study found that two years later, the bone density was nearly 5-7% lower at the spine and over 7-10% lower at the hip in the surgical group studied than the nonsurgical control group in their research using both the DXA and the complete CT scans. Yu and her team also found that the surgical patients had persistent and substantial increases in bone resorption markers, which is the process by which bones break down.

The bone loss in surgical patients occurred despite that they were not losing additional weight in the second year following surgery, and all had stable blood levels with adequate vitamin levels. This means that bone loss is probably not related to weight loss on its own.

Conclusion

This study leads to the question of when is bone loss going to stop? The study’s researchers recommend that weight loss surgeries with risk factors for osteoporosis receive bone density tests. It is common knowledge that obese adults do have higher bone densities than non-obese people.

The study’s team plans to continue to investigate possible causes for bone loss. Yu and her team speculate that major changes in the fat and gastrointestinal hormones could affect bone density in these patients.