Diet and physical activity behaviors associated with weight maintenance in bariatric surgery patients
Mehta, Tarun R.
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BACKGROUND: One of the most common long-term problems after bariatric surgery is weight regain, occurring between 18 and 24 months after surgery in 30% of patients.1 Weight regain after bariatric surgery supports the concept that obesity is a chronic, progressive disease that needs constant follow-up.2 To ensure long-term post-operative success, patients are recommended to adopt comprehensive lifestyle changes, which include adhering to a diet of at least 60-120 g/day of protein and engaging in mild exercise 20 min/day 3-4 days/week.3–7 Based on the current literature there is growing evidence that patients' health behaviors, including physical activity and protein intake, may play a significant role in weight loss and other postoperative outcomes.8–11 However, there is little long-term evidence for behaviors important for sustained weight loss following bariatric surgery. OBJECTIVE: The purpose of our research initiative was to determine whether protein intake and physical activity have an effect on maintaining weight loss in patients who underwent bariatric surgery 1-2 years earlier. METHODS: Our study included 368 patients who underwent bariatric surgery at Boston Medical Center from 06/01/2016-05/31/2017. We extracted baseline clinical data from electronic medical records (EMR), including gender, self-identified race, weight, height, date of birth, date of enrollment in the bariatric surgery program, and surgery date. We also collected self-reported physical activity (calculated as active metabolic equivalent [MET]-hours) and 24-hour dietary recall information from patients who had this data available in their EMR at least 1-year post surgery (n=121, 80.2% female), and assessed weight status through 06/01/2019. We conducted a retrospective analysis to observe the association of lifestyle factors with weight maintenance post-bariatric surgery. Prevalence and odds ratio (OR) were calculated for % weight regain (<2% vs. ≥2%) by active MET-hours & percent protein in diet, with adjustment for age, gender, race, and time to nadir weight. We ran additional analysis to test the combined effect of physical activity and high protein diet by comparing percent weight regain in those consuming a low protein diet (with any activity level) to those consuming moderate-high protein & lower active METS-hour vs. moderate-high protein & higher active METS-hour. RESULTS: Our study implemented two novel ways to examine physical activity and dietary recalls in the context of bariatric surgery patients, and how they influenced percent weight regain of nadir weight. Our results show that patients had an average of 84.4 pounds of weight loss at 1-year post operation, the average nadir weight was 179.0 pounds. However, many participants experienced weight regain after achieving their nadir weight. In fact, the average weight regain was 5.8 pounds. Patients who had active MET-hours <1.5 (n=78) had an average of 5.77 pounds regained after reaching nadir weight, compared to patients who had an active MET-hour ≥1.5 (n=43) who had an average of 5.89 pounds regained. But after adjusting for age, gender, and race, those who were less active (active MET-hours <1.5) did not have significantly higher odds of gaining more that 2% of their nadir weight back during out follow-up period (OR = 0.71 [CI 0.32-1.60]). Protein intake was defined as either a low protein intake (<26.7% protein of total diet) or moderate-high protein intake (≥26.7% protein of total diet). A patient consuming a low protein diet had 2.71 (CI 1.16 – 5.29) times the odds gaining ≥ 2% of their weight back from nadir compared to patients who consumed a moderate-high protein diet, after adjusting for age, sex, and race (p-value <0.05). After adjustments, those with moderate-high protein and low activity had 1.84 (CI 0.69-4.94) times the odds of ≥2% weight regain of nadir weight compared to patients who were moderate-high protein and higher activity, which, although not statistically significant, may be an important relationship to explore further. CONCLUSION: The findings indicate that consuming a moderate-high protein diet while engaging in physical activity tend to gain less weight after bariatric surgery in comparison to consuming less protein. There is also some evidence that those achieving moderate-high protein levels see an added benefit on weight maintenance if they are physically active. Future prospective longitudinal studies and strategies are needed to investigate implications further and define the magnitude of the association between protein intake, physical activity and bariatric surgery, as well as targeting various demographic subpopulations who might stand to benefit more from certain lifestyle interventions post-bariatric surgery.