Exactly what a well-balanced diet consists of is open to interpretation and will depend on each country as well as individual taste preferences, but in general, it's a healthy eating plan. Well-balanced diets are the opposite of fads or restricted plans. A restricted diet is usually low calorie and focuses on just a few foods; it may eliminate whole groups, such as grains or dairy. A fad diet is often extremely low in calories and may consist only of a single food, such as grapefruit or soup. In both cases, important nutrients are left out, whereas a well-balanced diet meets daily vitamin, mineral, calorie and protein requirements.

The main food categories that form what is usually considered a well-balanced diet are proteins, produce, grains and dairy. Healthy diets are often said to concentrate mostly on fresh fruits and vegetables. Whole grains are considered an essential part of a well-balanced food plan. Oats, wheat and other whole grains add good sources of fiber and nutrients to the body, whereas processed grains, such as those found in white bread, lack nutrition.

Healthy protein sources contain Omega-3 fatty acids rather than saturated fats. Omega-3 fatty acids are healthy fat sources found in foods such as salmon, walnuts and olive oil that are considered to be part of a well-balanced diet. Low-fat dairy products are included in many well-balanced diets, as they add some protein as well as important minerals such as calcium. Foods that are high in sugars or saturated fats such as chips, cookies and cakes should be eaten in small amounts only occasionally if they are to be part of well-balanced diets. High sodium, or salt levels, are found in many packaged and processed foods, and these should also be limited.

Well-balanced diets contain the necessary amount of calories, fats and nutrients that a person needs to function healthily while allowing him or her to maintain a proper body weight. While taking a multivitamin supplement is recommended by many physicians, eating a well-balanced diet is still necessary, as the body uses nutrients from real food more efficiently than those from supplements. Supplements, as approved by a doctor, are meant to nutritionally enhance a balanced approach to eating.

Within the definition of well-balanced diets there can be many different variations. For example, a vegetarian diet contains no meat, but can and should still be well-balanced by including other protein sources. A low-fat diet is still balanced in nutrients and types of food such as protein, dairy, produce and grains, but focuses on reducing unnecessary fats.