Hi there, 4lb is not a bad loss and depends on lots of things, like how much weight do you have to lose, have you been on another diet recently, what exactly you are eating and are you actually sticking to 800 calories and not eating any white carbs which will hold fluid. Are you compensating for exercise by having slightly more calories thinking you can do that. Also, what is your fluid intake like and are you getting plenty of good fats and oils. As you can see there are so many combinations of reasons. Do keep on with it as reversing (or reducing) your diabetes is much more important than actual weight loss. You should also be peeing lots as that is a sign the fat is leaving the body.