I've got a solid amount of experience using met and I've never really had that feeling. Met is known to blunt hunger. It is interesting and wonder if others have had a similar experience but I definitely haven't.
Probably 250 protein on non training days, 320 training, lots of fatty fish, carbs vary probably 200-300 grams. I have been geating much the same before I started the metformin but since I started it at 500 mg twice a day I just crave sugar and often feel mildly hypo it is an odd feeling. I did search the net and find some female non bodybuilding forums complaining about something similar. Perhaps I am just a whiny little girl! I really want to reap metformin benefits but it has not happened I stuck it for about three months but have now taken a break and cravings are gone again.
Also just realised my predictive typing entitled the thread surgery rather than sugary cravings.
Interesting, I deal with a LOT of people on metformin.. endocrine system is my day to day.. this is actually pretty common albeit more so in females.. pcos, etc.
Usually this happens at the beginning of treatment when your blood glucose drops and you crave carbohydrate. Some people find this is a mistaken craving for good old h20, but this is more common in type 2 diabetics.