After Having Bipass Surgery My Sister Lost 180 Lbs. However,

After having bipass surgery my sister lost 180 lbs. However, after she stopped just drinking the protein shakes and began eating, she found she could not eat anything that could not dissolve in water immediately..like chicken, steak, any meats, lettuce, veggies etc. The only thing she can eat is chips, donuts, pretzels, etc and yes she has gained all her weight back. Someone told me that she might have a "web"..something that blocks the real food from going to the stomach...can you explain what a "web" is?
My email is YYYY@YYYY Thank you.