What is the main causes of the pimples that come out on someone's skin? is there any related to the food that we eat?

Many causes: Acne (pimples) is a multifactorial skin disease which has many causes. These include genetics, stress, environment, hygiene, hormones, products used on face. Food can be a factor in some. It usually occurs in those with larger pores and oilier skin. If you notice that your acne worsens with certain foods then you should try to avoid those foods.