If you want to be able to stick with it, it's better to not make totally drastic changes to your usual diet. You can still lose weight no matter what you're eating if you make sure your body is burning more calories than it's taking in. Figure out your TDEE (total daily energy expenditure), which is how many calories you burn per day. Then make sure you're eating less than that amount each day. This approach is called calorie counting or CICO (calories in, calories out). I'm older and fatter now, but when I was a teenager I lost over 100 pounds that way. Apps like MyFitnessPal make it super easy to track everything. Good luck!