What's more important nutrition or exercise?

I'm a 16 year old teenager who works out at the gym 4-5 times a week. My main goal is to get a lean and toned body. I've been working out for about 6 months now and I've noticed the progress I'm making is quite slow. I'm 5'8" and weigh 71kg and I have a lot of fat around my torso area, especially love handles. I've been trying to burn fat while also gain muscle but Im not seeing as much progress. I try and eat as healthy as I can and have 1 cheat day where I eat junkies like chocolate and chips etc. but I want to know wether I should be focusing more on nutrition or exercise?