Is it normal for a mother to do this?

She's doing this on purpose. You could always say to her,"I know what you are trying to do and I don't appreciate it. You are too old to be carrying on in such a immature fashion. How can I be proud of you as a parent when you are bitch?!" Look her hard into her eyes as if you are trying to see into the deepest recesses of her soul. Then, dramatically turn on your heel and walk out of the door.

For whatever reason, she's sabotaging you. Does she need to lose weight too?

When I was a little kid my parents used to get me to eat as much as an adult. I would always say "I'm full" but they just wanted to make sure I wouldn't be hungry later or anything. I head the "There are kids in Africa who would love to eat what you're eating" so many times +_+ lol Idk, it's just a parents thing :P because I also wasn't too skinny at that age and completely healthy.

Oh! Also... My both my grandparents struggled financially. Life was really hard when they were kids =/ So, after finding that out I got why they are always trying to make sure I eat a very healthy and huge lunch :P

She's probably just looking after you. In a weird way but she is! =) And maybe there's a reason too. Ask her why she cares so much =)

My grandmother's like that..."Oh you've lost weight...have some cake/chocolate/ice cream." Counter productive. Thanks. Can I remind you of this next time you tell me I need to eat healthier? (I now eat healthier than she does...)

However...you never actually specified if you actually NEED to lose the weight. While it is possible your mother is just unhelpful, perhaps you're actually a healthy weight already, and she's concerned about your wellbeing.