Sit at a computer for 18 hours a day with no exercise, and then have disturbed sleep, that will help!
Suggest going to 4 then 5 meals a day with extra protein to keep your muscle mass higher, but you REALLY should see a nutritionist, or dietician. The high protein quick shakes could be added as between meal snacks until you slowly stretch the stomach capacity again.
Good luck, but do make sure you get some professional guidance.