Background: As the rates of obesity and morbid obesity continue to rise in the United States, gastric bypass procedures have increased respectively. Gastric bypass surgery typically results in significant short-term weight loss for most patients (61.6 percent of excess body weight for Roux-en-Y gastric bypass and 47.5 percent for gastric banding), with concomitant reductions in comorbidities such as diabetes, hyperlipidemia, hypertension, and obstructive sleep apnea. However, the duration of weight loss and improved health status has not been thoroughly studied.
The Review: Shah and colleagues reviewed the literature on the long-term effects of Roux-en-Y gastric bypass and gastric banding on weight and related diseases. Only articles with at least three years of postoperative follow-up in which patients had achieved maximal weight loss were included.
Results: Most of the available studies were case series or cohort studies. All studies showed initial substantial weight loss followed by a decrease in excess weight loss (weight regain) over the postoperative years (up to 16 years of follow-up). The percentage of weight regained was minimal in some case series, but all studies had several weaknesses (e.g., lack of control groups, significant drop-out rates, incomplete comorbidity data). One prospective study reported similar initial weight loss and tendency to regain weight at two and 10 years after surgery, but it showed that recovery from hypertriglyceridemia, low high-density lipoprotein levels, type 2 diabetes, hypertension, and hyperuricemia persisted at both follow-up points. Because these improvements were much less impressive at the 10-year mark, the authors suggest that comorbid diseases tend to recur as weight is regained.
None of the studies were designed to clarify the reasons for weight regain, although one reported gradual but steady increases in daily caloric intake from six months to four to 10 years after surgery. The prospective study reported increased physical activity in patients after surgery but did not objectively assess the effects or amount of that activity. Other studies have reviewed metabolic rates and gut and adipocyte hormones in maintenance of weight loss and weight regain, but the results are inconsistent.
Conclusion: The authors conclude that although bariatric surgery may be an appropriate therapy for morbidly obese patients, weight regain seems to mitigate the advantages over time. Randomized controlled trials are needed to better determine long-term effects on weight maintenance, comorbidities, and mortality.