Weight-Loss Surgery May Weaken Bones of Adolescents and Young Adults: Study

Bariatric weight loss surgery being performed by a doctor. (Shutterstock)

An increasing number of American children and teens are resorting to weight-loss surgeries to combat severe obesity. However, a recent study has revealed that these surgeries may have detrimental effects on their bone density and strength at a time when young people should be focusing on building optimal bone mass.

Researchers conducted a two-year prospective trial involving 54 participants aged an average of 18 years. Among the participants, 25 underwent sleeve gastrectomy, and 29 didn’t undergo surgery but received dietary and exercise counseling (pdf).

Young adults and teenagers who had the surgery and experienced substantial weight loss displayed weaker bone structure compared to their counterparts who had similar levels of obesity but did not undergo surgery, according to the results.

“We found that bone strength was lower two years after weight-loss surgery, while bone marrow fat, a marker of bone weakening, was increased, suggesting that weight-loss surgery has negative effects on bone health,” the study’s lead investigator, Miriam Bredella, professor of radiology at Harvard Medical School, said in a press release.

Biomechanical non-contrast CT analysis of the vertebra of an 18-year-old obese woman. (Courtesy of the Radiological Society of North America)

Sleeve gastrectomy has emerged as one of the most common forms of weight-loss surgery. The procedure involves the removal of approximately 75 to 85 percent of the stomach. Consequently, the amount of food the body can consume and absorb is restricted, leading to long-term weight loss.

Adult bone loss has been observed after bariatric surgery in previous research. A 2020 study found that individuals who underwent Roux-en-Y gastric bypass, a weight-loss surgery that reduces the size of the upper stomach, had a higher likelihood of experiencing a decline in bone quality.

Why Bone Health Is Crucial in Young Adults

The surgery’s effect on bone health is “clinically important,” according to Dr. Thomas Link, a professor of radiology, and Dr. Anne Schafer, a professor of medicine, epidemiology, and biostatistics, both at the University of California in San Francisco, who wrote a review of the study. "Adolescence is a time for building up bone mass, which will serve as a reservoir for one’s entire adult life before it steadily declines in the later stages of adulthood.”

The majority of bone growth and accrual of peak bone mass occurs during this time. Insufficient bone mass during this period can have long-term consequences on bone health, such as decreased bone density and compromised bone strength, making individuals more susceptible to fractures and osteoporosis later in life. Fractures associated with osteoporosis can have severe consequences, including chronic pain, limited mobility, disability, and decreased quality of life.

Why the Increase in Weight-Loss Surgeries Is Concerning

The American Academy of Pediatrics issued a policy statement in 2019 emphasizing the importance of enhancing access to metabolic and bariatric surgery for adolescents when medically necessary. There was a notable rise in the total number of completed youth bariatric surgeries—from 1,135 in 2020 to 1,349 in 2021, representing a nearly 19 percent increase.

The statement, believed to have influenced the increase in bariatric surgeries among young individuals, has sparked concerns regarding its potential impact, especially on younger children, considered a vulnerable population. Some doctors are hesitant to recommend bariatric surgeries for this group, highlighting that they are irreversible, invasive procedures with potentially lifelong consequences, and the availability of long-term data is limited.

Bariatric surgery should not be performed in preadolescent children, pregnant, or breastfeeding adolescents (and those planning to become pregnant within two years of surgery), nor in "any patient who has not mastered the principles of healthy dietary and activity habits and/or has an unresolved substance abuse, eating disorder, or untreated psychiatric disorder,” the Endocrine Society stated in a 2017 guideline on pediatric obesity, in conjunction with the European Endocrine Society and the Pediatric Endocrine Society.

In January 2023, the American Academy of Pediatrics released a comprehensive guideline reiterating its position and advocating for increased access to bariatric surgery for adolescents in need. The guideline emphasized the safety and efficacy of obesity treatment in children, stating that teenagers aged 13 and older with severe obesity should be evaluated for metabolic and bariatric surgery.

Obesity is defined as having a body mass index (BMI) at or above the 95th percentile for children and teens of the same age and sex. Severe obesity is defined as having a BMI that is 120 percent of the 95th percentile for age and sex. According to the U.S. Centers for Disease Control and Prevention (CDC), 19.7 percent of children and adolescents, or about 14.7 million aged 2 to 19, are obese.

Study Limitations

The study authors acknowledged certain limitations of their research.

Firstly, the participants were not randomly assigned, and it was observed that individuals in the surgical group had higher BMIs.

Secondly, although the study aimed to examine the long-term risk of bone fractures, the follow-up period was limited to 24 months.