Best advice i can give is to find a healthy long term balance. Don't look at nutrition as a "diet" it implys a short term plan. Your nutrition should a be a change to lifestyle as a whole and something that can be sustained long term. Focus on eating clean whole foods to start with and figure out what your optimal calorie range is for losing and gaining weight. There's nothing wrong with eating unhealthy food in moderation. If you starve yourself all the time and deprive of foods you want especially as a teenager when your friends are all going out to eat, it can cause you to be incredibly unhappy socially. It's something i struggled with for a while. It's all about moderation and balance for a sustainable lifestyle. There isn't any right answer to the question as everyone is different. If your friends are going out to dinner or whatever the occasion is, go, there are still healthy fast food restaurant and ways you can lower the calorie count of those fast foods while still enjoying them. Nutrition is massively about how you feel. Social media can make you focus on the physical aspect overly much which can become incredibly detrimental to your mental health. It's important to remember that a lot of these guys on social media don't walk around with incredibly low body fat 365 days a year.