Understanding Nutrition

From deciphering the basic food pyramid to unraveling the science behind the latest fad diet, the subject of proper nutrition is one that is often misunderstood. While nutrition is a relatively simple concept to grasp, the confusion lies in the fact that nutritional requirements vary among individuals according to a number of factors including age, activity level and gender. These variations are generally a matter of proportion, however, as individual nutrients have different functions in the human body.

Carbohydrates

• Simply stated, all foods are broken down into three basic nutrients: carbohydrates, fat and protein. While all three are necessary for the health and maintenance of the body, the role of each nutrient in human health varies considerably. While no one nutrient is superior to the others, carbohydrates garner the most attention due to their abundance in many different food types as well as their popular role in supplying the body with energy.

  Carbohydrates are divided into two types, simple carbs (glucose) and complex carbs such as those found in fruits and vegetables. Though all carbs supply the body with energy, complex carbs are considered more beneficial than simple carbs due to their higher vitamin and mineral content as well as their slower absorption rate. The slower breakdown rate of complex carbs provides the body with sustained energy as opposed to the quick energy obtained by eating simple carbs commonly found in candy and sweets.

  Carbohydrate requirements vary significantly among individuals, especially in regards to physical activity. While the recommend nutritional allowance (RNA) of carbs for a healthy, average adult is about 40 percent of their daily dietary consumption (or 800 calories in a 2000 calorie diet), physically active adults need a higher proportion of carbs, up to 50 percent and even 60 percent of their daily caloric intake to meet the increased energy demands placed on their bodies.

Proteins

• Along with carbs, a healthy diet should include adequate amounts of protein to promote muscle growth as well as to make necessary repairs to the body. Scientifically speaking, proteins consist of branched chains of amino acids necessary for the proper maintenance of the human body. Proteins are generally found in meat and dairy products, but are also quite abundant in beans and legumes.

  Proteins are divided into two categories: complete (those containing all of the essential amino acids required by the human body) and incomplete (those that contain only a partial list of necessary amino acids.) While meats and dairy products are classified as complete proteins, beans and legumes are considered incomplete sources of protein. This differentiation is significant for vegetarians or those consuming little or no meat or dairy in their diet as they need to obtain protein from a variety of different sources to ensure that they consume all of the essential amino acids required for general maintenance of the body.

  The RDA for protein for the average healthy adult is about 20 percent to 30 percent of the daily caloric intake (or 400 to 600 calories based on a 2000 calorie diet.) Athletes, and in particular body-builders, should strive to consume at least 30 percent protein to promote healing as well as prevent muscle degeneration brought on by excessive physical activity.

Fats

• Perhaps the least understood and feared nutrient of all is fat. Undeserving of its bad reputation, fats in adequate proportions are actually necessary for human health. Not only do fats serve as a backup energy source, but they also work in tandem with various hormonal systems in the body to ensure that these different systems are functioning optimally.

  Fats are classified into three categories: saturated (most meat products), unsaturated (various oils) and polyunsaturated (fish products such as salmon). A healthy diet is limiting in its intake of saturated fats (about 10 percent) while a combination of unsaturated and polyunsaturated fats are preferred. A fourth type of fat produced artifically and commonly referred to as trans fats should be avoided. Trans fats are typically found in fast food items due to their lower cost.

  While it is common knowledge that consuming too much fat (especially saturated or trans fat) in the diet is unhealthy, it is less known that consuming too little fat can also be harmful. Inadequate fat in the diet can actually disrupt various hormonal systems in the body, causing a number of problems that can severely impact health. Since fat serves as a backup energy source, inadequate intake can also negatively affect energy levels as well as impact the body's ability to regulate its core temperature.

  The RDA for daily fat requirements also varies among individuals and ranges from 20 to 30 percent of daily caloric intake. For weight loss purposes, a daily caloric intake of 20 percent fat is desirable. However, for individuals pursuing physical endurance goals such as running a marathon or mountain climbing, the upper limit of 30 percent daily fat intake or perhaps slightly even higher is necessary for supplying the body with its long term energy needs.