My 13 year old sister is having some pimples, although avoiding fast and oily foods including chocolates. is it natural with age?

Yes: It's normal during adolescence for acne to occur in both males and females. It is not caused by eating the wrong foods, but by a combination of hormones, bacteria on the skin and oil from the glands in the skin. Treatment is usually effective in lessening the pimples.

Acne: It is important to treat your acne so that you don't get permanent scarring. Some patients wait too long before seeing their dermatologist to have their acne treated. Normally topical medicines and internal antibiotics are used to keep acne under control. You can start with an over the counter benzoyl peroxide wash while you are waiting for your appointment with your dermatologist.