I was exhausted for a good 2 weeks post surgery. I am talking sit on the couch, lay in bed don't do anything kind of exhausted. My doctor said that was normal, some people just don't recover very fast. Honestly, I didn't start getting the increased energy that I kept hearing people talk about until 8 weeks out (I am 11 weeks now). In fact I didn't get back to my "old self" until I hit that 8 week mark. I have lost 65 pounds in 11 weeks and haven't used my CPAP machine since surgery. Everyone is different; while some people feel great and energized right after surgery, others, like me, take weeks to feel normal let alone energized. But your husband is still very early out from major surgery so I would venture the exhaustion he is feeling is normal. However, if it continues too long, tell the doctor. There are several vitamin deficiencies that can cause low energy. While the VSG surgery has less risk of long term vitamin deficiencies, for the first few weeks it can be hard to get all the nutrients your body needs. If all else fails and you are seriously worried, call the doctor. That is what they are there for. Mine was very clear about that fact.