if a person has a lifestyle where they eat mcdonalds everyday or they only eat fastfood they are more likely to get diabetes, heart disease, or cancer because fastfood like that isnt really food and i would tell you what its made out of to make more of a point but i'll spare you the gory details (*cough* tho i must say velveta has no dairy in it what so ever:) sorry)
Many people look up to certain celebrities and want to follow their examples. Even the bad ones. Peer influence is very real and very active in schools and even at works. Children will follow their friends example even if they know it is wrong, simply because of peer pressure