The restriction has physical symptoms. It’s a tightness across your chest. I find myself thumping my chest as if that will help move the food through my digestive system & ease the tightness - it doesn’t. The goal is not to feel the restriction as it is generally a signal you’ve eaten too much. Sometimes, though, I find it sneaks up on me. Stress, eating denser food or foods that sit heavily in my tummy (bread, pasta, rice, cous cous, potato, & such) can set it off early when I’ve eaten very little.
You wont start to feel it until you’re more healed & on solid foods. It does fade over time & as you get better at recognising when you’ve eaten enough - not full but enough that you don’t need the next bite. Learning to recognise the difference between needing to eat & wanting to eat is some of that head work that gets talked about.
Vomiting can occur but generally you’re more likely to experience the foamies. You may feel your restriction at the same time because food is ‘stuck’ because it’s too dry, too coarse or you’ve eaten too big a bite or too quickly. You’ll spit up slimy foamy saliva & may regurgitate (not the deep muscle cramping of vomiting) the last bite or so of what you ate. My nose often runs with it. Often after you bring up that bit of food you can continue to eat after a short break. Another one of those learning things & getting to know your body’s idiosyncrasies. It’s not a common or frequent occurrence.
You may not get a drain after your sleeve surgery. I didn’t & no one I knows did, though seems more common in the US.