^I'm so confused about the drink ENSURE?.plizz tell me will i gain or lose weight?

I really would like to gain weight. But i started thinkin in myself that maybe its for ppl who want to b on DIET, that why they drink it. Cuz i wonder, why do they have it in cermecial too. If it was something that would make a person gain weight, i dont think they wouldve put it on TV. plizz tell me something?. I dont wanna lose weight. im 19, n weight 102 pnds. i want at least 10 more. n i can eat meals with it too. its been two days i started drinkin. should i continue?