A variety of strategies can be used to identify healthy food and junk food. The division between healthy food vs. junk food is not absolute, but healthy foods typically contain more vitamins and minerals, lower levels of sodium and chemical additives, and healthier oils and fats. Nutrition labeling offers the most effective tool for determining the health of food. If nutritional data is not available, then visual cues and a few simple rules of thumb can serve instead.
Junk food is generally understood to be food that is high in calories but low in useful vitamins or minerals. Such food often gets many of its calories from unhealthy saturated fats. Much junk food is also laden with chemicals, sweeteners that add calories, or sodium. Desserts and snacks are especially likely to fall into this category. Minimally-processed foods such as fatty cuts of meat are typically excluded from this category even if they are not terribly healthy.
Food in most nations is required to carry nutritional information labels, although vegetables, meats and other minimally-processed or unprocessed foods may be exempt from this restriction. When labels are present, the separation between healthy food vs. junk food is easy to spot. Healthy food should provide essential macronutrients such as protein, useful roughage in the form of fiber, or vitamins and minerals. Foods with high levels of trans-fat, saturated fat, sodium, or calories from added sweeteners are more likely to qualify as junk food.
If food labels are not present, a few simple rules of thumb can be used to settle the healthy food vs. junk food question. Natural foods are typically healthier than foods that have been chemically processed. Fruits and vegetables should almost always be considered healthy foods. Colorful fruits and vegetables are typically very healthy, as rich green, purple, and red hues are often produced by chemical compounds with significant health benefits.
Visual inspection can prove useful in making a distinction between healthy and unhealthy foods when eating out. Color remains a useful guide when assessing the healthiness of vegetables. Food that shimmers beneath a layer of fat is likely to qualify as junk food. High calorie beverages such as sweetened soda and alcohol should be treated as junk food, as they contain many calories and few if any nutrients.
In some cases, the processing techniques used on food may move them from one category to another. While apples certainly fall on the healthy side of the healthy food vs. junk food divide, the relative health benefits of eating an apple would be lost if that apple was first dipped in a thick rich layer of caramel sauce. An onion is a useful source of fiber but should be considered junk food when breaded and deep-fried.