Most people go about their day eating whatever may sound appealing, not considering what the nutritional value is of what they are consuming. Poor diet can have an injurious impact on health; causing deficiencies as well as health-threatening conditions like obesity and weight gain and metabolic syndrome, and such common chronic systemic diseases as cardiovascular disease and diabetes. There are seven major classes of nutrients: minerals, carbohydrates, proteins, vitamins, fats, fiber and water that are essential for human life. Let's evaluate some nutritional information.

Today's food labels list the nutritional value of the product inside to help you better evaluate the nutrient content in a single serving of a food item. It is provided by law and uses established daily values to compare foods from product to product on a consistent basis, as well as providing the nutrient and energy information of the food.

Minerals

Dietary minerals are the chemical elements required by living organisms, and are present in common organic molecules. They include macro-minerals like calcium, magnesium, and sodium, as well as trace minerals such as cobalt, copper, chromium, iodine, iron, manganese, nickel and zinc. Nutritional supplements are available too.

Carbohydrates

Complex carbohydrates take longer to metabolize since their sugar units are processed one-by-one off the ends of the chains. Simple carbohydrates are processed quickly and thus raise blood sugar levels more quickly resulting in rapid increases in blood insulin levels compared to complex carbohydrates.

Protein

Protein is composed of amino acids that are our body's structural materials like muscles, skin and hair. The body requires amino acids to produce new body protein and to replace damaged proteins that are lost in the urine. Amino acid requirements are classified in terms of essential and non-essential amino acids. Consuming a diet that contains adequate amounts of essential amino acids is particularly important for growing animals.

Vitamins

As of 2005, twelve vitamins and about the same number of minerals are recognized as "essential nutrients", meaning that they must be consumed and absorbed in nutritional supplement form - or, in the case of vitamin D, alternatively synthesized via UVB radiation - to prevent deficiency symptoms and death.

Fats

Fats are composed of fatty acids bonded to a glycerol. Fat is classified as either saturated or unsaturated. Generally, saturated fat is solid at room temperature while unsaturated fat is a liquid. Unsaturated fats may be further classified as mono-unsaturated or poly-unsaturated. Trans fats are saturated fats which are created from unsaturated fat by adding the extra hydrogen atoms in a process called hydrogenation.

Fiber

Dietary fiber consists mainly of cellulose that is indigestible because we do not have enzymes to digest it. Fruits and vegetables are high in dietary fiber. Dietary fiber is important because it provides bulk to the intestinal contents and stimulates peristalsis - the rhythmic muscular contractions passing along the digestive tract.

Water

About 70% of the non-fat mass of the human body is made of water. Normally, about 20 percent of water intake comes from food, while the rest comes from drinking water and beverages. Water is excreted from the body in multiple forms; through urine and feces, through sweating, and by exhalation of water vapor in the breath.

Nutritional value standards and recommendations in the US are under the supervision of the US Department of Agriculture. Exercise and dietary guidelines from the USDA are under the heading of the food pyramid, which has replaced the concept of the four food groups.