How to cheer a girl up?

I’m in highschool, and I’ve been flirting with a girl, we have each other on snap and have a streak going. She snapped me a picture of her in the mirror. She looked beautiful, but I noticed that there was writing on it, “I’m skinny”, “I’m not fat”, “I’m beautiful”. I was concerned, she definitely wouldn’t be described as fat, nor would she be described as scrawny and skinny either. I’m concerned and want to make her feel better, how should I do that? Or is it none of my business?
How to cheer a girl up?
Post Opinion