I am 4 years out of an open gastrectomy partial obstruction surgery and 3 years out of the gastric bypass to repair gastroparesis from a perforated ulcer. Yes, I was overweight and the surgery helps me lose weight. But it has left me for the rest of my life with a malabsorption Disorder. So I do get iron treatments. Every 3 weeks. I do take all of my medications liquid. I do have chronic bowel obstructions.
Now I'm a female so my malabsorption issues are going to be different than yours as a male. My best advice is to Take your vitamins. Get your blood work. Have a great doctor when you retire. And keep up your protein. Live life like you've lived it the day after surgery 20 years from now.