Yes I was like that for the first few weeks, I felt absolutely dreadful, had absolutely no energy and felt dizzy a lot. When I spoke to the dietician she said it was quite common after surgery and with the sudden big reduction in calorie intake. She also advised to drink as much as I could. I only really picked up and felt much better after I had my b12 injection and moved on to 'proper' food. Hope you feel better soon x