You see them counted on food labels and now on restaurant menus. But do you know what calories are?
Anya Guy, a Mayo Clinic dietitian, says calories are units of energy. And even though they are all technically the same, the effect they have on your body can differ depending on what kinds of food you eat.
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"A calorie is a unit of energy," Guy says. "It is calculated for various types of foods, more so in the categories of calories from carbohydrates, protein and fat."
She says calories are all technically the same.
"In the laws of science ... all calories are created equal, but our body breaks down carbohydrates, protein and fat very differently," she says.
And, while 1,000 calories from a fast food burger and fries are technically the same as 1,000 calories from lean meats, fruits and vegetables, Guy says there are other health implications you should consider when picking which foods to eat.
"I recommend the majority of your calories come from unprocessed or minimally processed whole foods, since the quality of your calories can impact your weight and your overall health," Guys says.
She says everyone's calorie requirements are different. But getting 2,000 calories a day from lean chicken, whole grains, fruits and vegetables is going to keep you healthier than getting 2,000 calories a day from processed foods that are high in sugar and saturated fats.