The U.S. Department of Agriculture regularly reviews and revises its Dietary Guidelines for Americans, issuing a new set of guidelines every five years. The goal of each successive set of guidelines is to provide Americans with the information they need to eat a healthy diet, based on current nutritional research. A primary focus in each edition is how much of the day's caloric intake should come from each type of food. The more ideal the nutritional composition of a food, the more valuable it is as a source of calories.
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2010 USDA Guidelines
The 2010 Dietary Guidelines were released in January 2011. They replaced the often-criticized food pyramid with a new metaphor called MyPlate, as a simpler way to visualize an optimal division of foods by category. The new symbol divides a stylized plate into larger and smaller portions for fruits, vegetables, grains and protein, with "dairy" represented as a glass beside the plate. If the foods on your plate are represented in roughly the same proportions, you're probably eating a well-balanced diet.
MayoClinic.com breaks down the current guidelines by percentages. The largest percentage of daily calories should come from carbohydrates the body's main fuel, totaling one-half to two-thirds of the day's calories. The majority should come from vegetables and fruits, and the remainder from grains. For optimal health and nutrition, most of the grains should be from whole grain products such as oatmeal and whole wheat bread. Most beans and lentils offer quality carbohydrates as well as protein.
Proteins are necessary for the body to grow and repair itself. Protein can account for 10 to 35 percent of a balanced diet, and can be derived from many sources. Dairy products, meats and fish are all high in protein. So are vegetarian sources including peas and beans, soy products such as tofu and many grains. The 2010 guidelines emphasize switching from red meats with saturated fats, to leaner meats and vegetable sources.
Fats are one of the most contentious topics in dietary circles. The 2010 guidelines suggest that fat be limited to no more than 20 to 25 percent of the day's calories. Furthermore, those fats should be unsaturated as often as possible. Use monounsaturated and polyunsaturated oils as your cooking fats, wherever possible. Avoid processed foods that contain hydrogenated oils and their associated trans-fats, which are the unhealthiest of all. Fats are necessary to the body's health and function, and should not be reduced below 15 percent of the daily total except on medical advice.