Skipping meals is never a good idea, as your body needs the nutrition. Healthy weight loss happens at a rate of 1-2lbs per week, max, so if you're losing more than that you need to step back and re-assess what you're doing. Ideally you should eat 3 meals per day, and 2 snacks. You should, hopefully, also do some sort of exercise for 30 mins a day, even if it's just light cleaning.
Skipping meals can cause hunger and cravings. Or, more severe, it can cause a large calorie deficit, which would make you lose weight even faster, but could also cause health problems like malnutrition.
Not eating lunch isn't a good idea, and your friend's advice (to skip breakfast as well) is even worse.
Without more info (age, weight, height, gender, goal, calorie intake, activity level) it's hard to give you specific advice, but skipping meals is rarely the answers, especially for teens.