how to gain weight

I don't really feel like eating so much lately even though i try to consume as much as i can tolerate. Has anyone taken any meal replacements such as ensure to get to and maintain a normal, healthy weight? (without giving or making d any worse)Also, I've looked at the first three ingredients for ensure and it's water, corn syrup, and sucrose. I'm thinking that it is probably not the best option but i'm not sure what other meal replacements there are.Thanks