3 year old son is obese

At my son's 3 year old appointment in January, I noticed his BMI was in the 90th percentile, aka overweight (39inches tall and 39lbs). His pediatrician was not concerned at the time. He has been large his whole life, height and weight percentiles consistently in the high 90s. But I just measured him because he's growing out of his clothes, and he is now 40 inches and 42lbs, which is in the 95th percentile, obese.I'm worried sick. He has a huge appetite and would eat non stop if we let him (like, he would eat 2 sandwiches if it was up to him). He does eat kid stuff like chicken nuggets, PB&J, and pizza. But he also eats strawberries, blueberries, peaches, bananas, oranges, carrots, broccoli, cauliflower, peas, and tomatoes. He eats what we eat at dinnertime, which includes stuff like baked chicken, spaghetti, stir fry, and Indian food. I am in the process of losing weight, and he eats a lot of the same food I do (low calorie bread, cauliflower tater tots, tons of turkey, zucchini noodles, etc). We do not routinely keep candy, cookies, or ice cream in the house, although he does eat it sometimes, like if he brought home treats from a Valentines day party at school. He has a half cup of pear juice in the morning to keep him regular, but otherwise it's just water and 2% milk for liquids.He is fairly active, although I admit we could cut back on screen time (1-2hrs daily right now). He plays soccer at preschool and we go to the playground at every opportunity. I've also signed him up for soccer during the summer too.I'm so concerned about his weight, but I'm not sure what to do about it. Any suggestions? via /r/Parenting http://bit.ly/2Zwimg1