Preoperative weight loss improves bariatric surgery outcomes, according to findings from a single-institution retrospective analysis. The weight loss came from following a 4-week low-calorie diet (LCD) and was of greatest benefit to patients who lost 8% or more of their excess weight. These patients had a greater loss of excess weight in the 12 months following surgery, as well as shorter average hospital length of stay.

The results appeared online in the Journal of the American College of Surgeons .

Preliminary studies indicated that short-term weight loss before surgery might reduce surgical complexity by reducing the size of the liver and intra-abdominal fat mass, but it remained uncertain what effect weight loss might have on long-term outcomes.

The LCD included 1,200 kcal/day (45% carbohydrates, 35% protein, 20% fat), which were consumed through five meal-replacement products and one food-based meal. Liquids included at least 80 ounces of calorie-free, caffeine-free, carbonation-free beverages per day. Patients were also instructed to conduct 30 minutes of moderate to vigorous activity per day.

Deborah A. Hutcheon, DCN, and her fellow researchers analyzed data from their own institution, where a presurgical 4-week LCD with a target loss of 8% or more of excess weight had been standard policy already. The population included 355 patients who underwent sleeve gastrectomy (n = 167) or Roux-en-Y gastric bypass (n = 188) between January 2014 and January 2016.

Almost two-thirds (63.3%) of patients achieved the target weight loss before surgery. There were some differences between the two groups. The group that achieved the target contained a greater proportion of men than did the other group (25.5% vs. 13.7%, respectively; P = .013), a higher proportion of white patients (84.8% vs. 74.1%; P = .011), and a higher proportion of patients taking antihypertensive medications (68.3% vs. 57.3%; P = .048). The two groups had similar rates of preoperative comorbidities and surgery types.

Those who achieved the target weight loss had a shorter hospital length of stay (1.8 days vs. 2.1 days; P = .006). They also had a higher percentage loss of excess weight at 3 months (42.3% vs. 36.1%; P less than .001), 6 months (56.0% vs. 47.5%; P less than .001), and at 12 months (65.1% vs. 55.7%; P = .003).

After controlling for patient characteristics, insurance status, 12-month diet compliance, and surgery type, successful presurgery weight loss was associated with greater weight loss at 12 months.

SOURCE: Hutcheon DA et al. J Am Coll Surgeons. 2018 Jan 31. doi: 10.1016/j.jamcollsurg.2017.12.032.