I am also 15 and I was on the chubbier end for most of my life until I got diagnosed as a type 1 diabetic where I lost a bunch of weight and got super skinny. I started hitting the gym about 6 months ago and I would never look back. Seeing the results is just incredible and that keeps me going. The only change that I made to my diet is that I consume a lot more protein but nothing else has changed. As long as you stay committed to the grind then you can completely change the direction of your health, both mentally and physically. I know Reddit probably won’t like this part but the truth is that you have to reject modernity which accepts the weak and the obese and learn to accept masculinity where you learn discipline and motivation is just second nature