a. RYGB resulted in weight loss in high-fat diet (HFD)-fed NZO mice. NZO-Chow, NZO chow-fed mice (n = 8); NZO-HFD, NZO mice with HFD starting at 6 weeks old (n = 8); NZO-SHAM-PF, sham surgery and pair feed with HFD starting at 6 weeks old (n = 8), and NZO-RYGB, RYGB with HFD starting at 6 weeks old (n = 10). NZO-RYGB vs. NZO-HFD, p < 0.01 from 2 weeks to 12 weeks; NZO-RYGB vs. NZO-SHAM-PF, p < 0.05 from 6 weeks to 12 weeks, and NZO-SHAM-PF vs. NZO-HFD, p < 0.01 from 4 weeks to 12 weeks post-surgery. b. RYGB improved hyperglycemia in HFD-fed NZO mice. NZO-Chow, chow-fed NZO mice (n = 8); NZO-HFD, HFD-fed NZO mice (n = 8); NZO-SHAM-PF, NZO mice with sham surgery and pair feeding (n = 8), and NZO-RYGB, HFD-fed NZO mice with RYGB (n = 10). NZO-RYGB vs. NZO-HFD and NZO-SHAM-PF, p < 0.01 from 6 weeks to 12 weeks post-surgery. The shaded area represents a normal range of lean mouse blood glucose levels.