Diet schemes? HELP

So, I’m 17 and have recently started to be worried about my weight. When I was in my early teens I wasn’t the skinniest and had quite a lot of fat on me.

When I got to 15-16 I lost a lot of weight and became skinnier. I had ab lines and was very healthy.

Now I’m 17, and I’m not fat but I have put on some weight on my lower stomach and thighs and I want to loose it again and change back to the way I used to be.

I try to go to the gym and do body combat once a week as that is the only time I can go but haven’t been in a while, which I’ll be starting again next week.

What is the best way to loose the weight on my thighs and lower stomach other than the gym and working out?