High-quality proteins contain sufficient components, called amino acids, needed to support growth in children and promote health in adults. Protein quality is affected by digestibility and the type and amounts of amino acids present. In general, animal sources of protein are considered complete, whereas plant proteins lack one or more of the essential amino acids needed to support growth and maintain health. Eating lean protein helps lower cholesterol levels and decreases the risk of developing heart disease and other life-threatening illnesses.

In order to improve the quality of plant-based proteins, eat a variety of plant foods that have differing amino acid contents. When combined together, their amino acid composition approximates that of higher-quality proteins. The protein quality is thus higher than for each of the foods individually. Complementary protein foods do not need to be eaten at the same meal; eating them on the same day is sufficient to receive the high-quality protein benefits.

Carbohydrates are a group of nutrients that include organic compounds such as sugar, starch and cellulose. Most of the carbohydrates in your diet come from plant foods, such as grains, fruits, vegetables, legumes and nuts. The main role of carbohydrates is to provide your body with energy, which is primarily in the form of glucose. Different types of carbohydrates are categorized based on the amount of sugar molecules that they contain.

Simple carbohydrates are those that contain only one or two sugar molecules linked together, which are called monosaccharides and disaccharides, respectively. Common monosaccharides include fructose, or fruit sugar, and galactose, which is found in dairy products. Sucrose, or table sugar, is a common disaccharide, as is lactose, which is the predominant sugar in dairy products.

Complex carbohydrates are those that contain more than two sugar molecules linked together. These carbohydrates are referred to as polysaccharides and may contain anywhere from three to several hundred sugars. Examples of polysaccharides include fiber, starch and glycogen.

Polyunsaturated fats are a type of healthy fat the body needs to function properly. When intake of saturated and trans fats are replaced with polyunsaturated fats, brain function and heart health are improved, according to the American Heart Association. Polyunsaturated fats are found in a wide variety of foods, including fish such as salmon, and vegetable oils such as soybean and corn.

The two main types of polyunsaturated fats are omega-3 and omega-6 fatty acids. Omega-3 fatty acids play a crucial role in brain function, growth and development, as well as reduce inflammation and help lower risk of heart disease, cancer and arthritis. Omega-6 fatty acids can help to stimulate the growth of skin and hair as well as regulate metabolism, and promote

bone and reproductive system health. Maintain a balance of the two fats in your diet -- while omega-3 fatty acids help reduce inflammation, omega-6 fatty acids can promote inflammation.

The typical dictionary definition of a fruit is the fleshy, edible ovary of a seed plant, or the flowering part of a plant that will flower again. It is the food that grows that contains seeds, and nuts and seeds are often classified as fruit. Vegetables are defined as the parts of plants that are cultivated for eating, such as roots (celery), stems (hearts of palm), leaves (spinach) and buds (broccoli).

The reason it's easy to mix up fruits and vegetable is that they are in fact quite similar. They are both parts of plants, either trees or bushes, that grow from the ground. They both can be fleshy and many fruits are salad-oriented, which makes them seem like vegetables: avocados, tomatoes and olives to name a few. They are both healthy, mostly low fat and packed with nutrients that make them excellent choices for healthy diets, both for living and losing weight.

Fruits often are much sweeter than vegetables and except in more nouveau faire usually are served at the end of the meal. Vegetables are generally less sweet and sometimes even salty or bitter, and usually are served as part of a meal. Vegetables typically are parts of the plant that are grown for eating, such as stalks and leaves, while fruits often are grown on the plant, not as part of it.

In terms of fat loss, vegetables will be a main staple of your daily nutrition.  Fruits, however, are higher in sugars and carbs, therefore should be limited during a phase where fat loss is the main focus.  After you have achieved your ideal body composition, fruit may be slowly re-introduced into your nutrition at a level your body will accept without storing unwanted carbs!