Night shift work is prevalent in the United States with notable negative health consequences. Here, we study the outcomes of bariatric surgery upon night-shift (NS) and day-shift (DS) workers.


A retrospective chart review of 1047 patients that underwent gastric bypass between 2003 and 2016 was performed. Patients working outside the hours of 8:00am to 8:00pm were identified as night shift workers. Using Student’s t-tests, BMI, excess body weight loss (EWL), and metabolic risk factors were compared between the night-shift and day-shift workers.


34 night-shift workers were identified. Night-shift workers had an average age of 47.97±1.72 and an average preoperative BMI of 47.88±1.68, compared to day-shift workers who had an average age of 45.44±0.34 and an average BMI of 46.89±0.24. Both cohorts lost a significant amount of weight at 3 (NS: 38.62±2.41%EWL, p=0.0014; DS: 41.76±0.45%EWL, p<0.0001), 6 (NS: 60.46±3.85%EWL, p<0.0001; DS: 61.31±0.59%EWL, p<0.0001), and 12 months (NS: 74.39±4.02%EWL, p<0.0001; DS: 74.23±0.71%EWL, p<0.0001) after surgery. No significant change in the percentage of excess weight loss at 3, 6 and 12 months was recorded between the two groups (all p>0.05). Night-shift workers displayed significantly higher levels of HbA1C preoperatively (NS: 7.13±0.30%; DS: 6.32±0.04%; p=0.0005). A significant change occurred in HbA1C 12 months postoperatively (p=0.0015) when comparing night-shift workers (pre, 7.1±0.30% to post, 5.6±0.13%) and day-shift workers (pre, 6.3±0.04% to post, 5.5±0.02%). Diabetes remission one year after surgery was similar in night-shift and day-shift workers. Night-shift workers, unlike day-shift workers, see no significant improvements in their levels of LDL (NS: 96.92±6.82 to 100.3±9.97 mg/dL, p=0.6695; DS: 110.8±1.08 to 94.3±1.07 mg/dL, p<0.0001), cholesterol (NS: 177.2±7.97 to 165.6±11.06 mg/dL, p=0.4303; DS: 182.8±1.21 to 168.5±1.27 mg/dL, p<0.0001), triglycerides (NS: 161.5±30.09 to 99.54±12.21 mg/dL, p = 0.096; DS: 150.6±3.61 to 96.47±2.20 mg/dL, p<0.0001), lipoprotein-A (NS: 32.93±7.09 to 20.13±8.1 mg/dL, p=0.085; DS: 27.98±1.32 to 21.75±1.27 mg/dL, p=0.0078) and homocysteine (9.61±0.74 to 8.99±0.74 μmol/L, p=0.372; DS: 10.03±0.15 to 8.98±0.18 mg/dL, p<0.0001).


Night-shift workers achieve similar benefit postoperatively in weight reduction and HbA1c reduction, but fail to see similar benefit in biochemical cardiac risk factors. Night shift workers may need additional therapy including change in work shifts to achieve similar benefits as day shift workers undergoing weight loss surgery.