Boyfriend doesn’t eat often. Help!

I don’t know how to get him to eat more. He’s 5’10 and 125 lbs. He’s really skinny and usually only has one meal a day and he says he’s gotten lazy to eat and I don’t know what to do. He would end up getting some sort of fast food like taco bell or mcdonald’s. What should I do? It worries me and we’re both 18 :/ I tell him to eat but that doesn’t really do much but I was thinking of making him food every now and then so he would at least eat.