How do I stop my mum from being suspicious in terms of my eating?

I want to start eating less, but healthier, and I don't want her to get suspicious and pissed off at me. I'm 165cm (5'5'') and 53kg (116lb), so I'm not overweight, I just wish to be a bit slimmer. I have no desire at all to be anorexic or to be stick thin, I just want to be a bit more confident. Help?