People nowdays are not healthy due to a sudden incresease in consumption of Junk Food and a lack of a proper and balanced diet. In today's world there is no place for food with nutritional value. Junk food like Pizza, Burger, Fries, Smilies, Noodles, Buns etc..... have replaced the nutritional food. That is why Due to these sudden changes in the food habits of today's people they are not healthy.
Hope it helps!!!