Short-term weight loss before surgery leads to better outcomes

Patients who lose at least 8 percent of excess weight just one month before the bariatric surgery have an increased probability of losing additional in the year following surgery, according to researchers from the University of South Carolina School of Medicine, Greenville, SC. Apart from surgery, diet and weight loss before the operation may also determine how successful a person is in losing weight during the first year after the procedure.

"Currently, controversy exists for the optimal preoperative dietary optimization of patients prior to bariatric surgery,” said study co-author John David Scott, associate professor of surgery, University of South Carolina School of Medicine, Greenville, and the metabolic and bariatric surgery director of Greenville Health System (GHS), SC. “On one side, insurance policies often mandate six or 12 month weight management programmes. This mandate is in direct contrast to many bariatric surgeons, who prefer to use short-term, calorie-restricted diets several weeks prior to surgery in order to optimize outcomes."

The paper, ‘Short-Term Preoperative Weight Loss and Postoperative Outcomes in Bariatric Surgery’, published in the Journal of the American College of Surgeons, sought to determine what impact short-term pre-operative excess weight loss (EWL) has on postoperative outcomes in patients undergoing primary vertical sleeve gastrectomy (SG, n=67) or Roux-en-Y gastric bypass (RYGB, n=188).

Led by Dr Deborah A Hutcheon, a clinical nutrition specialist at GHS, the study involved 355 patients who undertook the recommended four-week low-calorie diet before surgery, between January 2014 and January 2016 at GHS. The study patients were asked to lose at least 8 percent of their excess weight by following a 1,200 calorie diet for four weeks immediately preceding their operations. For the analysis, the patients were divided into two groups based on whether they actually achieved that weight loss goal (224 patients achieved that goal, and 131 did not). Primary endpoints included percent excess weight loss (% EWL) at one, three, six and 12 months postoperatively.

Patients achieving ≥8% EWL preoperatively experienced a greater %EWL at postoperative month three (42.3±13.2% vs 36.1±10.9%, p<0.001), month six (56.0±18.1% vs 47.5±14.1%, p<0.001), and month 12 (65.1±23.3% vs 55.7±22.2%, p=0.003). Median operative duration (117 minutes vs 125 minutes; p=0.061) and mean hospital length of stay (1.8 days vs 2.1 days; p=0.006) were also less in patients achieving ≥8% EWL.

There were no significant differences in follow-up, readmission or reoperation rates were seen. Linear regression analysis revealed that patients who achieved ≥8% EWL during the four-week low-calorie diet lost 7.5% more excess weight at postoperative month 12. This finding was consistent even when other factors such as age, gender, ethnicity, and health problems including high blood pressure and diabetes were considered.

Patients who lose some excess weight prior to weight loss surgery achieve greater weight loss after surgery, and also experience shorter hospital stays and shorter procedures (Credit: American College of Surgeons)

Hutcheon explained that there is this key window of opportunity after bariatric surgery, up to 18 months, when many physical and metabolic changes occur that help facilitate weight loss.

"After that time point, patients will have to rely on diet and exercise and lifestyle management to maintain that weight loss," she said. "One of the things we often say is bariatric surgery is a tool; it's not the end-all-be-all for weight loss. So it's really about making sure this tool is used wisely and proactively by our patients and having it work most effectively in the long run.”

Scott explained that the most important aspect of this study is that it adds to the body of research data showing that it is beneficial for bariatric surgery programmes to encourage and counsel patients to follow a short-term diet or aim to achieve weight loss prior to bariatric surgery.

"Our ultimate goal was to see what makes postoperative outcomes better for our patients undergoing this lifesaving procedure," he said. "We call it the honeymoon period of bariatric surgery. After a year or year and a half, your body starts to figure out what it can and can't do, and your behaviours may change a little bit, so the odds that you are going to lose a significant amount of weight after that time period are definitely decreased. Therefore, the more weight you can lose during that honeymoon period, the better, because that effort will help establish a set point, in terms of where your steady weight is going to be further down the road."

For future investigations, the researchers hope to explore the impact that pre-surgery weight-loss programs have on longer term (more than one year) surgical outcomes.

"Ultimately, we believe that preoperative preparation for bariatric surgery should be mediated by individual surgeons taking care of their patients and this 8 percent target should not be used as a hard set point to qualify patients for bariatric surgery,” he concluded. “Because patients with obesity who weren't able to achieve that 8 percent goal still had dramatic effects in terms of how much weight they lost and comorbidity resolutions."