The Surprising Long-Term Complication of Bariatric Surgery

Conditions / April 10, 2015


Lara Pizzorno is the author of “Your Bones: How You Can Prevent Osteoporosis and Have Strong Bones for Life – Naturally” and a member of the American Medical Writers Association with 29 years of experience specializing in bone health.

Recently we asked Lara if she would help us provide a series of short, ongoing videos to help you (our customers and readers) stay up to date on the latest facts and science related to bone health and overcoming osteoporosis naturally.

In this latest video, Lara discusses the long term consequences after bariatric surgery (you may be surprised). Watch the video below (or read the transcript provided) and let us know what you think in the comments. 🙂

Hello, my name is Lara Pizzorno, and I’m the author of Your Bones. And I’m here today to share some information with you that I hope will help you or someone you love to have healthier bones.

In the last couple of videos we’ve been talking about the latest research findings on the affects on our bones of the surgical procedures that are now being used to treat obesity, which are called bariatric surgeries. The two most commonly performed bariatric surgeries are the Roux-en-Y
gastric bypass and the sleeve gastrectomy.

After seeing two very recently published papers, one in the February and the other in the March, 2015, issues of the Journal of Clinical Endocrinology & Metabolism that confirm that both of these procedures cause significant ongoing bone loss, I spent the past couple of weeks reading numerous papers on the adverse affect because the use of both of these surgeries is just increasing astronomically.

As the prevalence of severe obesity has increased by 70% in just the past decade, in the U.S. now 35% of Americans are morbidly obese. So have the number of gastric bypass procedures. From 1998 to 2008, the number of patients undergoing gastric bypass procedures has increased by 761%.  And these procedures are mostly being done in young and middle-aged people. And once they’re done, they cannot be reversed.

So the topic of this video is what are the long term consequences of bone after bariatric surgery? What happens to bone in the first two years? And how are patients doing nine to ten years after bariatric surgery?

To answer the first question, we can look at the two studies that were just published in February and March, 2015, issues of The Journal of Clinical Endocrinology and Metabolism. Both of these studies looked at what happens to bone within the first two years after bariatric surgery.

In the study that was published in the February issue, fifty obese adults were recruited from the Massachusetts General Hospital Weight Center and the surrounding community, and thirty of them were undergoing Roux-en-Y gastric bypass surgery, while twenty others, who were not having surgery but were of similar age, sex, and weight as the surgical group, were used as controls. The average age of the subjects in this study was 47 years.

In the group of thirty patients who were receiving gastric bypass, 53% were pre-menopausal, 13% were men, and only 33% were post-menopausal. So the majority of those undergoing gastric bypass, 66% of these people, were either pre-menopausal women or men in their 30’s and 40’s, and therefore should not have been at risk for increased bone loss. In fact, young and middle-aged obese people are often found to have higher than average bone density, which is thought to be a result of carrying around the extra weight, that it puts a mechanical load of stress on the bones and causes them to get stronger.

The people in this study that were undergoing gastric bypass were counselled to get twelve to even fifteen hundred milligrams of calcium everyday along with three thousand IU of vitamin D through a combination of diet and supplements.


Their bone density was then checked when the study began, and then six months, twelve months, and twenty-four months after they had undergone gastric bypass surgery. And here’s what happened.

Weight stabilized six months after surgery, but rapid bone loss, which began very quickly after surgery, continued in all sites checked, the hips, the spine, the lower arm and leg, through the end of the two years of the study.

Let me repeat, in all areas of the skeleton, bone mineral density did not slow down, but kept dropping throughout the two years of the study. The structure of these patients’ bones, which is called the micro-architecture in the bone, was checked in the wrist and in the shin bone, and it had deteriorated so greatly in the gastric bypass group that by the end of the study, these changes resulted in a nine to ten percent decrease in bone strength in both areas. So these people were now at much greater risk of breaking a bone if they fell.

Bone density in the non-surgical group did not decline. As expected, it remained stable, which, because these people were young pre-menopausal people, their bone density should not have dropped. But this also confirmed that something very different was happening in the people who underwent gastric bypass surgery.

And here is what’s to me, the scariest part. This bone loss happened even though average blood levels of calcium and vitamin D and parathyroid hormone were maintained within the normal range of gastric bypass patients as well as the controls over the two years.

Why is this so scary? Because blood levels of calcium, vitamin D, and parathyroid hormone are key mechanisms through which bone loss is typically regulated.

If you have a copy of Your Bones, you can read all about parathyroid hormone and its relation to bone loss there. If you don’t, here is a tweet sized version. Parathyroid hormone levels go up when blood levels of calcium drop too low. Parathyroid hormone increases the body’s production of the most active form of vitamin D, which helps us to absorb more calcium from our intestines, if we haven’t had gastric bypass, at any rate. But parathyroid hormone also increases osteoclast activity and bone resorption, or bone breakdown, to liberate calcium from bone, because calcium has many immediate uses in the body compared to which its loss from bone takes much longer to cause life threatening problems.

So in these people, rapid bone loss was occurring despite having normal blood levels of calcium, vitamin D, and parathyroid hormone. And what this means is that gastric bypass surgery is upsetting something else, or lots of something elses. And researchers are just now beginning to try to figure out what’s going on. There are a number of other hormones beside parathyroid hormone and the hormonally active form of vitamin D that impact bone remodelling, and we don’t yet know which are impacted by bariatric surgery or what to do about it. We’ll talk more about what’s been going on with it and what to do about it in the next video.

It’s important here to mention that most of the obese patients in this study had high bone density before their surgery.

As I mentioned, young and middle-aged obese individuals are often found to have higher than average bone mineral density because carrying the extra weight around puts an extra load on bone that signals it to become stronger so it won’t break. Most of the participants in this study, the one that was published in February, were young adults. So despite the fact that they loss significant amount of bone, they still remained within the normal bone mineral density range for now.

And that’s how this research is probably going to be reported. As if bariatric surgery effects on bone are not a problem. But if bone loss keeps occurring at this rate, just think about where they’re going to be when they get to their 50’s and 60’s. It’s not surprising that the short term follow-up two years after surgery showed no increase in fracture rates, but research that was published in January, 2014, in the Journal Osteoporosis International, which provides data on longer term follow up, seven years after surgery, found a three-fold increase in spine fractures and a five-fold increase in hip fractures after bariatric surgery. Another study that evaluated patients more than ten years after Roux-en-Y revealed that 65% were vitamin D deficient, and 69% now had elevated parathyroid hormone levels.

The other just published, two year study, the one that was published in the March issue of The Journal of Clinical Endocrinology and Metabolism, looked at whether the two types of surgery, Roux-en-Y gastric bypass and sleeve gastrectomy, might have different effects on bone.

The study participants in this paper were 52 pre-menopausal women, average age of just 40, who underwent Roux-en-Y gastric bypass, and 38 pre-menopausal women whose average age was 41, who had sleeve gastrectomy, so some of the women in both of these groups were only in their 30’s.

In both groups, those receiving either Roux-en-Y or sleeve gastrectomy, bone mineral density in the lower spine and all over the hip began dropping immediately, and it kept on dropping. The overall loss in total body bone mineral density was 18%.


Even in this group of young people, two fragility fractures occurred in the Roux-en-Y gastric bypass group.


One was a radius fracture, which is the lower arm bone, and that happened after fourteen months. And the other was a humerus, or upper arm bone fracture, which occurred after seventeen months.

So how significant is the bone loss that typically occurs after gastric bypass?


The best data we currently have on this is provided by a review that was published in 2012 and included 15 perspective studies. The perspective studies are those in which similar people, who differ with respect to some factor that the researchers want to investigate, are followed over time. In this case, the similar people were obese individuals, some of whom had gastric bypass surgery while others did not. And the outcome in question was bone loss.

The data from the 15 studies included in this review shows that after the first year after gastric bypass, bone mineral density in the hip dropped an average of 9.2 to 10.9% in the top portion of the femur, or thigh bone, which is where most people experience hip fractures. But declines in hip bone mineral density of as much as 15% were seen in some individuals during the very first year. In all of these studies, patients were counseled to take supplemental calcium and vitamin D.

So it’s undeniably clear that bariatric surgeries trigger ongoing, excessive bone loss. To quote the authors of a paper in which people were followed for 7.7 years on average, “Bariatric surgery which is accompanied by substantial biochemical, hormonal, and mechanical changes, is associated with increased risk of fracture.”

Obviously, this does not bode well for the long term health for those undergoing gastric bypass procedures. But given the continued increases in morbid obesity that we’re seeing worldwide, bariatric surgery is not going away. And its benefits in treating obesity and the many co-morbid conditions or diseases that accompany it, like diabetes, cardiovascular disease, and sleep apnea, are unquestionable. It definitely helps.

The question is, can its highly damaging effects on nutrient absorption and bone be prevented? Or at the very least, lessened?


To answer this question we have to understand why patients taking supplemental calcium and vitamin D are still experiencing massive drops in bone mineral density. What’s causing this? What are the mechanisms responsible for bone loss after gastric bypass? We don’t really know yet. But in our next video, I’ll share with you what the current theories are.

Thanks for tuning in and I hope this was helpful to you.



Sturm R, Hattori A. Morbid obesity rates continue to rise rapidly in the United States. Int J Obes (Lond). 2013;37(6):889–91. PMID: 22986681,

Scibora LM, Ikramuddin S, Buchwald H, et al. Examining the link between bariatric surgery, bone loss, and osteoporosis: a review of bone density studies. Obes Surg. 2012 Apr;22(4):654-67. doi: 10.1007/s11695-012-0596-1. PMID: 22271358

Yu EW, Bouxsein ML, Putman MS, et al. Two-year changes in bone density after Roux-en-Y gastric bypass surgery. J Clin Endocrinol Metab. 2015 Feb 3:jc20144341. [Epub ahead of print] PMID: 25646793

Nakamura KM, Haglind EG, Clowes JA, et al. Fracture risk following bariatric surgery: a population-based study. Osteoporos Int. 2014 Jan;25(1):151-8. doi: 10.1007/s00198-013-2463-x. Epub 2013 Aug 3. PMID: 23912559

Karefylakis C, Näslund I, Edholm D, et al. Vitamin D status 10 years after primary gastric bypass: gravely high prevalence of hypovitaminosis D and raised PTH levels. Obes Surg. 2014 Mar;24(3):343-8. doi: 10.1007/s11695-013-1104-y. PMID: 24163201

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