Junk food is one example of unhealthy food. This type of food is typically high in sugar, salt, food additives, and unhealthy varieties of fat.
Speaking of fat, this is the source of a great deal of misunderstanding. For example, saturated fat and trans-fats are very unhealthy, where as other types of fats, such as omega-3 and omega-9 (especially in the correct ratio) are essential to your health.
Refined food is probably one of the biggest culprites when it comes to unhealthy food. When food is refined, it looses much of the nutritional value and dietary necessities present in whole foods. It also oxidizes, and oxidized food is unhealthy food.
Food additives are another cause of unhealthy food. Preservatives, for example, have to problems. Many preservatives are unhealthy, even carcinogenic. The use of preservatives often indicates a flawed food processing system, where the food is exposed for too long. Watch out for this in tinned food. Canning should keep the food fresh, so there is normally no need for preservatives in canned food.
Heavy metals and other toxins are another cause of unhealthy food. These enter the food chain in many ways, including industrial pollution, pesticides, veterinary treatment of agricultural animals, and growth hormones.
Unhealthy food should be avoided by all, especially for those with allergies. Unhealthy food could be a factor in triggering allergies in the first place.
- Wikipedia on junk food
- Wikipedia on fat
- Center for Science in the Public Interest (food safety. The rest of the site is interesting too)