I am so Parinoid!
That said, your personal diet history, age, sex, activity level, medical issues etc will be a factor in how quickly you lose. I'm 56, female, mildly active, hypothyroid and was maintaining 270# on 15-1800 calories a day. Of course I'm going to lose slower than a 30 yo male that has a physical job and used to eat 4-5000 calories a day. So? I'm still losing and feel better than I have in a very long time.
Trust the process. Pay close attention to your sleeve. Name it. Make friends with it. It's your new partner in weight loss and WILL help you if you let it.
Highest 303.4, Surgery 263, Current 217.8, Goal 180
Its pretty simple math. With a sedentary lifestyle just sitting around you burn about 2200 to 3400 calories in a 24 hours period just living and your body processing "stuff". It takes 3500 calories to create a lb.
If you are sticking to the plan you should be consuming about 600-800 calories. It would take you 5 to 6 days to eat enough to gain a pound. If you don't exercise you should still lose about .5 to 1 lb a day. Now that is an overly simple explanation of how it all works and does not mean you should not exercise because your muscles will shrivel to nothing and your heart would give out in short order, but my point is that with a smaller stomach unless you are eating snickers at every meal and ice cream between meals, you should lose weight.
Don't get me wrong, you can screw it up, you have to stick to the plan your doctor gave you and you do need exercise. Your body needs fiber for elimination, you need water for proper hydration, these are all factors that could contribute to not losing. Not getting enough water will cause you to retain water, retaining water means GAINING weight. 1 gallon of water weighs 6 lbs. If you are only getting 32 oz of water a day and your body starts retaining it in survival mode, in 4 days you could theoretically gain 6 lbs. Exercise mean sweat, sweat means the expulsion of excess water which also cleanses your body of toxins.
Toxicity also plays a role in weight loss. If you are toxic from artificial sweeteners, artificial colors, etc. Your body will be slower to expel the other wastes in your body (i.e. fat). So eating organic and/or washing vegetables well is also helpful. Adding lemon juice to water helps detox efforts, certain herbal teas help too. I am not saying you need to go through any detox program or anything, Small things can yeid big results.