‘Forever Chemicals’ Curb Bariatric Surgery Success in Teens

Adolescents with higher levels of certain types of polyfluoroalkyl substances (PFAS) in their blood prior to bariatric surgery were significantly more likely to regain weight after the procedure than those with lower levels, a new study has found.

PFAS — synthetic chemicals used in many consumer products labeled as stain or grease resistant, waterproof, or nonstick — are present in most people’s blood and are associated with endocrine disruption and metabolic dysregulation, lead author Brittney Baumert, PhD, MPH, a postdoctoral research fellow in population and public health sciences at the Keck School of Medicine of the University of Southern California in Los Angeles, and colleagues wrote.

These compounds, nicknamed forever chemicals because they’re resistant to breaking down, are associated with reduced weight loss during dietary interventions and increased weight gain after those interventions in adults, but their weight-loss effect hasn’t been studied in adolescents, who are still undergoing developmental and metabolic changes that could make them more vulnerable to PFAS, the researchers added.

“With the use of weight-loss interventions increasing for the treatment of obesity, identifying modifiable risk factors for adolescents at greatest risk of regaining weight is especially important, as such insights could inform targeted strategies to enhance and sustain long-term success of these interventions,” Baumert told Medscape Medical News.

The rapid, substantial weight loss induced by bariatric surgery offered researchers an opportunity to study how PFAS might affect postoperative weight trajectories in teenagers, the researchers wrote.

For their study, published online in Obesity, Baumert and colleagues followed 186 adolescents who underwent bariatric surgery for obesity. The participants were part of the Teen-Longitudinal Assessment of Bariatric Surgery cohort who underwent the procedure between 2007 and 2012. The mean age of the study population was 17.1 years, 76.3% were girls, and 72% were white individuals. The primary outcome was weight regain after 5 years.

Researchers measured plasma concentrations of eight PFAS at baseline prior to surgery. The substances included three perfluoroalkyl sulfonic acids — perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluoroheptane sulfonic acid (PFHpS), as well as five perfluoroalkyl carboxylic acids — perfluorooctanoic acid, perfluorodecanoic acid, perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid.

More Weight Regain With PFAS Exposure

Higher concentrations of the three sulfonic acid-containing compounds (PFOS, PFHxS, and PFHpS) individually and in sum were significantly associated with larger annual BMI regain after surgery than lower levels during the period from 1-5 years after surgery.

For example, a baseline PFOS concentration of 1.45 log₂ ng/mL was associated with an estimated annual BMI regain of 1.34 compared with an estimated BMI regain of 1.84 per year for a baseline PFOS concentration of 2.94 log₂ ng/mL (P = .0497).

In addition, higher levels of the three sulfonic acid-containing chemicals were significantly associated with an increased waist circumference and reduced total percentage weight lost 1-5 years after surgery.

For the carboxylic acid-containing compounds, BMI regain during the 1-5 years after surgery trended lower the higher the chemical concentration level was at baseline, although the differences didn’t reach statistical significance, except for PFHpA individually. The baseline PFHpA concentration of -2.18 log₂ ng/mL was associated with an estimated annual BMI regain of 1.43 compared with a regain of 1.65 per year at the lower baseline concentration of -4.85 log₂ ng/mL (P = .05).

The PFHpA finding was unexpected and “may reflect complex pharmacokinetic or tissue-specific mechanisms,” the authors wrote. It underscores the complexity of PFAS mixtures and the value of assessing individual compounds and combinations of them to fully characterize exposure-related links, they added.

Although overall association between PFAS and post-intervention weight gain in teens was not entirely unexpected, given findings from previous studies linking higher PFAS exposure to weight regain in adults, the magnitude of weight regain was striking, Baumert told Medscape Medical News.

“Teens with the highest PFAS exposure regained nearly 47 lb within just 4 years of intervention, underscoring how environmental exposures may affect the long-term success of weight-loss interventions,” she said. “These findings have prompted us to explore whether PFAS also influence weight regain after other weight-loss interventions.” 

Implications for Patient Care

The study suggests that “persistent PFAS chemicals may contribute to weight regain even years after bariatric surgery,” Baumert told Medscape Medical News. The variability in individuals’ exposures “helps explain why some adolescents regain more weight than others, despite undergoing the same intervention,” she said. Consequently, PFAS may be a potentially modifiable risk factor, and reducing exposure could become part of personalized pre- and post-weight-loss intervention care, she added.

Strategies to reduce exposure include encouraging the use of PFAS-free cookware, avoiding microwaveable popcorn and other grease-resistant food packaging, and choosing fresh or frozen foods over takeout and prepackaged meals, the authors noted.

“Integrating environmental biomarker screening into clinical risk stratification tools could help tailor follow-up care and counseling, while upstream policies to limit PFAS contamination in food, water, and consumer products may further support long-term weight loss and metabolic health in youth,” Baumert told Medscape Medical News.

The study has some limitations. Its observational design limits conclusions of causality, Baumert said. Additionally, researchers lacked data on certain lifestyle and clinical variables, such as diet, physical activity, and endocrine conditions such as polycystic ovary syndrome, that could influence both PFAS exposure and metabolic outcomes. Studies with more comprehensive covariate data are needed to confirm and expand on the findings, she said.

PFAS Monitoring Challenges

“Bariatric procedures are an effective way to treat obesity and its associated comorbidities, but postoperative weight regain can compromise the metabolic health benefits from surgery,” Kulmeet K. Sandhu, MD, associate professor of surgery and associate director of minimally invasive and bariatric surgery at Cedars-Sinai Medical Center, Los Angeles, told Medscape Medical News.

The finding that higher levels of sulfonic acid PFAS were associated with higher weight regain, decreased total percentage weight loss, and increased waist circumference after bariatric surgery in teens was interesting but not surprising because of the evidence that PFAS interfere with regulation of metabolism, said Sandhu, who was not involved in the study. She agreed with the authors that it was surprising that PFHpA was inversely associated with BMI regain.

Monitoring PFAS levels in teens could present some clinical challenges, including the potential stress of blood sample collection, Sandhu noted. It also would require labs that have the capability to test for PFAS, and the results themselves may cause stress in adolescents, especially if they indicate rising levels, she said.

“These issues would need to be addressed with thoughtful conversations around testing and results before obtaining informed consent from the patients and their families,” Sandhu said.

Additional studies are needed to better understand the mechanisms by which PFAS interfere with metabolic regulation, especially in the bariatric surgery setting, and to explore whether avoiding PFAS can help decrease weight regain in this population, she added.

This study was funded by the National Institutes of Health National Institute of Environmental Health Sciences. Baumert disclosed no financial conflicts of interest. Sandhu disclosed consulting for Johnson & Johnson.