Association of postoperative dietary macronutrient content and quality with total weight loss and fat-free mass loss at midterm after sleeve gastrectomy

This study aimed to investigate the associations of macronutrient quantities and qualities with percentage total weight loss and percentage of fat-free mass loss relative to total weight loss in adults undergoing sleeve gastrectomy. This cross-sectional study included 146 patients on postoperative time since sleeve gastrectomy of 2 to 4 y. Diet was assessed using a food frequency questionnaire. Macronutrient quality index, carbohydrate quality index, fat quality index, and healthy plate protein quality index were calculated. The associations of dietary variables with percentage total weight loss and percentage of fat-free mass loss relative to total weight loss were determined using linear regression. Logistic regression was used to estimate the odds of non-response (percentage total weight loss < 25%) and excessive fat-free mass loss (percentage of fat-free mass loss relative to total weight loss > 28%) based on dietary intakes. Forty-six (31.5%) were non-responders, and 49 (33.6%) experienced excessive fat-free mass loss. The fully adjusted model showed a 0.75 decrease in percentage total weight loss per 5% carbohydrate increase (95% CI, –1.45 to –0.05). The odds of non-response were 53% lower per 5% increase in protein (95% CI, 0.23–0.94). Each 5-g higher intake of fat was associated with 0.29 higher percentage of fat-free mass loss relative to total weight loss (95% CI, 0.03–0.55). The odds of excessive fat-free mass loss were reduced by 5% per gram of fiber intake (95% CI, 0.90–0.99). Each 5% increment in energy intake from protein that was isocalorically substituted for either carbohydrate or fat was associated with lower odds of nonresponse. Macronutrient quality indices had no significant associations. Adherence to a high-protein, high-fiber diet after sleeve gastrectomy may enhance surgical success by improving total weight loss and preventing excessive fat-free mass loss.