True or false ?

So with my first pregnancy since my husband and I weren't really stable we would eat out a lot and my baby was 7 pounds. With this current pregnancy, i'm just not hungry , i'm almost 20 weeks and I either get full so fast or don't get hungry. Someone in my family keeps telling me " if you don't eat and keep doing what you're doing , that baby is going to come out skinny " is this true ? I mean no I don't want my baby to be underweight but I just can't force myself to eat it's hard