Talk to Dietitian/Nutritionist on Weight Loss Surgery. Post Surgery Life

My friend Adan has BMI 45. he is Diabetic type 2 with good control, A1c is less the7%. Taking HTN medicine, all labs are okay. No diabetes complications. the diet with low carbs, daily 40 minutes walk. A surgeon suggested him weight loss surgery (Bariatric Surgery). the Question is if he started more activated as 60 minutes walk with extra exeresis cut on extra calories etc or maybe the surgery will better for him. he only not ready for surgery due to post-surgery life, like vitamin deficiency, taking vitamin pills forever, taking liquid food for the too long time,etc, is that all right what he thinks or maybe just his fear? should he prepared hemdelf for weight loss surgery?cneed your great opinon.