Help! Sleeve patient how Can I gain 10 lbs

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I had the weight loss sleeve surgery in 2018. Im 5’4 and weighed 243 lbs. I was addicted to food and at the time it seemed like my best option. I lost 100 pounds within a year. Im waaay too thin. I’m 144 but would like to gain 15 pounds. Anyone out there that can tell me what to do. I get full fast, I started making shakes with weight gainer from GNC. I feel it helps with my calorie intake. Lmk any advise please....