If you stand at the edge of a picture, it will make your body look bigger than it is.
When you have your picture taken, don't stand near the edge of the picture, otherwise you'll look fatter than you really are.
この場合、次のような言い方ができますよ。
ーIf you stand at the edge of a picture, it will make your body look bigger than it is.
「写真の端に立つと、実際より体が太って見える」
the edge of a picture「写真の端」
to look bigger「大きく・太って見える」
ーWhen you have your picture taken, don't stand near the edge of the picture, otherwise you'll look fatter than you really are.
「写真を撮ってもらうとき、写真の端の方に立たない方がいいよ。じゃないと実際より太って見えるよ」
to have one's picture taken「写真を撮ってもらう」
to look fatter「太って見える」
ご参考まで！
カナダ 
