any tips for ways to lose body fat at 13 with bulking up with weights?

Answer 1

Combine weight lifting with cardio. Ride your bike, go skating, or skate boarding, run, and swim in the summer for cardio. All that new muscle is a fat burning power house. Muscle burns calories where fat does not. The more muscle mass you have (esp in the legs) the more calories you will burn. You will burn more calories doing your everyday stuff than someone with less muscle would doing the same things. You're on the right track.

Answer 2

At 13 you shouldnt be lifting heavy weights since your muscles havent fully developed yet. And lifting weight will not help to lose fat, unless you are using lightweights with high reps. Try doing the hydraulic circuit at a gym, or do cardio exercise (running, swimming, cycling, boxing) to tone up and get fit. These will strengthen your body and get you better equipped to hit the weights when you reach 16 or 17.

Answer 3

You need to introduce circuit training into your lifting. For example, less recovery time between sets, and use lighter weights. Also, don't neglect the cardio-vascular workout. The calories burned and the endurance you gain make it a very good part of the workout.
Also, don't get caught in the trap of eating BIG to be BIG muscled. Just eat a sensible diet, with a good amount of protein. Genetics also play a part in how muscular you get from lifing, but all things being equal muscle burns calories more, even when you sleep.. Go for it!