Calories are units of energy. The number of calories in a food or drink is an indication of how much energy it can provide to your body for use in metabolic processes or to fuel physical activity. When you consume enough calories each day, your body is able to use them all to move you around, take care of essential functions, and allow you to think.
When you eat too many, your body cannot use all that energy and it stores it for use in the future in the form of fat. When you eat too few calories to supply your energy demands, your body uses your fat stores, burning the extra calories they store.
We don’t all require the same number of calories each day for our needs, which is why it can be hard to know how many calories to consume. The USDA recommends that the average man eat about 2,700 calories per day while the average woman eats about 2,200.
But, if your metabolism is slower or faster than average, if you exercise a lot or a little, if you have a medical condition, or if your goal is to lose weight, your calorie needs will differ from these averages.
What About Macros?
We all need calories to survive, which is why food is one of the essentials for living, along with water and shelter. Your body needs the energy in food to keep you breathing, keep your heart pumping, and support brain function. When you read a food label, it will tell you how many calories, or how much energy, is in that food. It will also tell you how many of those calories come from carbohydrates, proteins, and fats, which are called macronutrients or macros. Not all calories are alike, and your body processes calories from various sources differently. One gram of carbohydrates has about four calories, as does one gram of protein. One gram of fat, however, contains about nine calories.
When you eat these macronutrients, they must be broken down into compounds your body can process.
Carbohydrates are your body’s preferred energy source, because they are the easiest for your body to access. There are simple carbohydrates, which are easily converted to fuel for your body, and there are complex carbohydrates, which take more energy to convert and burn.
Proteins are the second most common substance in your body, after water. Proteins are comprised of chains of amino acids, which your body breaks down and uses to perform many vital functions. Amino acids are required to rebuild your cells and tissues, to regulate your hormones, and for the healthy functioning of all your metabolic processes.
Finally, fats are necessary for nearly all your organs, including your brain. Fat keeps you insulated and protects your internal structures, and fat is a significant source of energy that we can store and use on-demand. Your body stores fat under the skin, called subcutaneous fat, as well as in the midsection, which is known as visceral fat. You need healthy sources of fat in your diet, but you only need small amounts of these macros.
Knowing precisely how many calories and how much of each type of macronutrient you need can be a bit of a guessing game, depending on your activity level, physical fitness, weight loss goals, and medical history. In general, healthy people do well when they eat a diet that contains between 25 and 45 percent of calories from protein, between 45 and 65 percent from carbohydrates, and less than ten percent from healthy fats. These ranges offer many options to fit your individual needs and focusing on healthy sources of foods will be vital to optimizing every calorie you eat.
Next week we will look at healthy sources of calories. Don’t forget to stick around until the end for free access to “The Ultimate Guide to Burning Calories“!