Three months of yoga before surgery revealed a surprising difference in stress hormones

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Oct 12 2026

As patients prepared for bariatric surgery, researchers examined whether three months of yoga could influence stress hormones, inflammation, and the molecular processes that regulate gene activity.

Study: Influence of yoga on the epigenetics of obesity: a study on its short- and medium-term benefits in the treatment of patients with severe/morbid obesity eligible for bariatric surgery. Image Credit: Studio Romantic / Shutterstock

In a recent study published in the journal Frontiers in Public Health, researchers in Italy examined whether structured yoga during preoperative care was associated with changes in stress-related hormones and DNA methylation in patients with severe obesity.

The prospective, non-randomized observational study analyzed 40 adult candidates preparing for bariatric surgery over a three-month preoperative window. After adjustment for baseline measurements, the yoga group had significantly lower plasma noradrenaline levels than controls, consistent with reduced sympathetic nervous system activation (the body's "fight-or-flight" stress response).

The study did not detect a statistically significant change in DNA methylation at the targeted sites in the three inflammatory genes examined.

Background

Obesity is a chronic disease frequently accompanied by chronic low-grade systemic inflammation and neuroendocrine dysregulation and is associated with a wide range of multisystemic comorbidities, including type 2 diabetes (T2D) and cardiovascular diseases (CVDs).

For patients with severe obesity (body mass index [BMI] of at least 35 kg/m² with comorbidities, or at least 40 kg/m² regardless of comorbidity status), bariatric surgery is an established treatment option that can produce substantial, sustained weight loss.

Preparing for and recovering from bariatric surgery can involve considerable physical and emotional stress, creating interest in approaches that may help patients manage stress before treatment.

While standard dietary counseling addresses metabolic health, researchers are investigating complementary mind-body interventions such as yoga for their possible effects on stress-related physiology.

Preliminary molecular studies suggest that mind-body therapies such as yoga may influence DNA methylation at genes involved in inflammation. Whether these effects occur in people with longstanding severe obesity remains uncertain.

About the study

This study aimed to address this knowledge gap and inform surgical prehabilitation (preoperative conditioning designed to prepare patients for surgery) by evaluating DNA methylation and secondary physiological, metabolic, and psychological measures in patients who underwent yoga before bariatric surgery.

The study was conducted in Milan, Italy, and initially enrolled 48 adults with severe obesity, of whom 40 were included in the analysis. Participants were assigned to one of two groups based on their willingness and availability to attend yoga sessions: a yoga group (n = 20) or a standard-care control group (n = 20). The researchers did not randomly assign participants.

Participants in the intervention arm were offered 36 supervised sessions of the PRANA_it yoga protocol over the three months before surgery, typically three 45- to 60-minute classes per week. They attended an average of 26 sessions. The protocol included movement sequences, pranayama (breath-control techniques), mantra, and relaxation, with modifications for limited mobility.

Study evaluations were conducted at three predetermined time points: at enrollment, before surgery following the three-month intervention, and three months after surgery. These evaluations included measurements of hormonal and neuroendocrine markers in blood and saliva, together with enzyme-linked immunosorbent assays (ELISAs) for selected serum biomarkers.

In parallel, participants' psychological health was assessed using three validated questionnaires: the Short Form-36 Health Survey (SF-36), the Beck Depression Inventory-II (BDI-II), and the State-Trait Anxiety Inventory (STAI-Y).

Finally, the study investigated changes in DNA methylation in the promoter and transcription-start-site regions of three inflammatory genes: tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP), using targeted enzymatic methylation sequencing. TNF-α methylation before surgery was the primary outcome; the other molecular, physiological, and psychological measures were secondary.

Study findings

The baseline-adjusted analysis found that plasma noradrenaline levels were significantly lower before surgery in the yoga group than in controls, consistent with reduced sympathetic activation. On average, noradrenaline fell modestly in the yoga group but rose in the control group; the analysis does not establish that yoga caused this difference. Noradrenaline was a secondary outcome, and randomized trials are needed to confirm this association.

Targeted epigenetic profiling showed that DNA methylation across the TNF-α, IL-6, and CRP promoter regions did not change significantly after accounting for multiple statistical comparisons. The researchers suggested that the short intervention period, small sample size, and reliance on blood samples might have limited their ability to detect methylation changes. In unadjusted analyses, circulating TNF-α protein increased more in the yoga group, but this finding was highly variable and did not establish an anti-inflammatory benefit. Circulating IL-6 and CRP did not differ significantly between groups before surgery.

Physical functioning evaluations revealed a greater average decline in self-reported SF-36 physical-functioning scores in the yoga group than in controls. However, after adjusting for baseline scores, the difference was no longer statistically significant. The authors suggested that this unadjusted shift might reflect a response-shift phenomenon (a recalibration of patients' internal standards of physical capability as bodily awareness increases), but they did not test this explanation.

Depressive symptoms declined in both groups, with a larger average reduction among yoga participants, but between-group differences were not statistically significant. State anxiety scores likewise showed no significant group difference. Neither weight loss nor markers of glucose regulation and insulin resistance differed significantly between groups during the preoperative period. After surgery, both groups experienced substantial weight loss and metabolic improvements, with no clear additional benefit linked to preoperative yoga.

Conclusions

These findings provide preliminary evidence that structured yoga before bariatric surgery is associated with lower plasma noradrenaline levels in patients with severe obesity. The study detected no significant DNA methylation changes in the three targeted inflammatory genes, and it did not establish psychological or metabolic benefits. It remains unclear whether the observed noradrenaline difference translates into improved surgical recovery or other clinical benefits. The small, non-randomized, single-center study was susceptible to selection bias and unmeasured differences in physical activity, medication use, and other factors. The study did not systematically record adverse events, limiting conclusions about safety.

Future randomized controlled trials (RCTs) with longer follow-up, larger samples, more comprehensive tissue sampling, and molecular analyses are warranted to confirm the noradrenaline association and investigate possible longer-term effects.