…in terms of weight loss, lowering of HgbA1c, and weight-related quality of life. The specific gastric bypass surgery used in the study is the Roux-en-Y version.
Average initial weight of participants was 104 kg (229 lb). Bypass patients dropped their weight by 25 kg (55 lb)and HgbA1c decreased by 1.8% (absolute decrease), compared to intensive medical management participants who lost 10.3 kg (32 lb) and dropped HgbA1c only by 0.4%.
I doubt that intensive medical therapy included a low-carb Mediterranean or paleo diet.
Source: Clinical and Patient-Centered Outcomes in Obese Patients With Type 2 Diabetes 3 Years After Randomization to Roux-en-Y Gastric Bypass Surgery Versus Intensive Lifestyle Management: The SLIMM-T2D Study | Diabetes Care