Calorie
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A: What are calories?
B: Calories are a way of keeping track of the body’s energy budget. A healthy balance occurs when we put in about as much energy as we lose. If we consistently put more energy into our bodies than we burn, the excess will gradually be stored as fat in our cells and we will gain weight. If we burn off more energy than we replenish, we will lose weight
A: How can we be able to measure the energy we consume and use?
B: We do so with a unit called the calorie. One calorie is defined as the amount of energy it would take to raise the temperature of one kilogram of water by one degree Celcius
A: How do these calories relate to calories in the food we consume?
B: Calories in food measure how much energy the item stores in its chemical bonds. That energy is released during digestion, and stored in other molecules that can be broken down to provide energy when the body needs it
A: How do our bodies use that energy?
B: Our bodies use that energy in three ways: about 10 percent enables digestion, about 20 percent fuels physical activity, and the biggest chunk, around 70 percent supports the basic functions of our organs and tissues. The third usage corresponds to your basal metabolic rate
A: What is that rate?
B: It is the number of calories you would need to survive if you weren’t eating or moving around. Adding in some physical activity and digestion, you arrive at the official guidelines for how many calories the average person requires each day. Researchers estimate 2000 calories for women and 2500 for men.
A: Do these estimates apply to everyone?
B: Not necessarily. These estimates are based on factors like average weight, physical activity, and muscle mass. If you are doing an energy-guzzling activity, your body could use up to nine thousand calories per day. Pregnancy requires slightly more calories than usual. Elderly people typically have a slower metabolic rate. Energy is burned more gradually, so less is needed
A: How can I measure my own calories?
B: Before you do that, you should know that calorie counts on nutrition labels measure how much energy the food contains, not how much energy you can actually get out of it. Fibrous foods like celery and whole wheat take more energy to digest, so you would actually wind up with less energy intake. Some foods also offer nutrients like protein and vitamins, while others provide far less nutritional value. Eating too many of those foods could leave you overweight and malnourished. Even with the exact same food, different people might not get the same number of calories. Variations in things like enzyme levels, gut bacteria, and even intestine length, mean that every individual’s ability to extract energy from food is a little different
A: So, there isn’t any way to count exactly the amount of calories I need
B: Yes. You need to factor in things like exercise, food type, your body’s ability to process energy