MODEL RELEASED. Junk food. Teenage boy smiling as he takes a handful of popcorn from a bowl. Junk foods such as popcorn, cakes, biscuits and crisps are considered unhealthy as they may contain high levels of sugars and saturated fats. The sugars may lead to tooth decay, while excessive amounts of saturated fats can cause obesity and raise the risk of heart disease. Junk food contains few of the vitamins and minerals essential to health.