Calories: Functions, Importance and Recommended Intake
Calories are one of those things that get talked about and thrown around as if we all completely understand what calories are. Calorie counts appear on just about all food packaging labels. We all have a basic understanding that we need to pay attention to calories.
But there is the real science behind the term calories. Calories play an essential role in our fitness and health. Calories are simply abstract numbers to be counted. When we talk about calories, we should probably have some understanding of what we mean.
The fact is, not all calories are bad. We need calories in our diet to fuel our bodies. It is when we consume too many calories that we run into problems. And it is not only the number of calories that matter. The minds of calories we consume also determine how healthy they can be.
What are calories? What do we mean when we talk about the number of calories in foods and drinks? What are the different kinds of calories? And what is the importance of calories? We will give you everything you need to know about calories so you can be better equipped to stay healthy and fit.
What are calories?
First, some may find it surprising that calories are not a substance in food like vitamins, cholesterol, or fats. Calories are a unit of measure of the energy content of foods and beverages.
A calorie is the amount of energy it takes to raise the temperature of 1 kilogram of water by 1 degree Celsius. This sounds extremely technical but as we will see, it translates into some understandable features of foods and drinks.
Calories as a unit of measure translate into the energy you derive from the things you eat and drink. Even maintaining the most basic functions of your body requires calories. When we consume excess energy stored in the form of calories, we retain that excess in our bodies. This is where we find one of the most central issues in fitness.
Too many calories, or too many of the wrong kinds of calories, will be stored in the body and this is what leads to weight gain. We need to burn the calories we consume, or we will retain the sources of those calories.
How do calories work?
To survive, we need energy. We require energy for those most elemental functions like breathing, pumping blood, and even digesting food. Anything the body does requires energy. The amount of energy we derive from food is measured in calories.
In essence, the number of calories in food is a measure of potential energy. That is, the energy we may derive from the foods we eat but remains unused. A gram of carbohydrates, for example, contains 4 calories. A gram of protein also contains 4 calories. But a gram of fat contains 9 calories. To make sure this potential energy meets our bodily demand, we need to make sure we do not take in more calories than we use. But we also need to make sure we take in enough calories to support the energy demand of the body.
By way of an example, a pack of maple and brown sugar oatmeal contains 260 calories. If we examine the nutrition information, we find that this pack of oatmeal contains 2 grams of fat, 4 grams of protein, and 32 grams of carbohydrates. This equals 162 calories (slightly more than the product label offers).
When we eat this oatmeal, our bodies break down the constituent components of the food, with the help of enzymes and digestive chemical reactions, into glucose and other sugars, glycerol and fatty acids, and amino acids. These are transported through the bloodstream to the areas where they are needed and absorbed by our bodies. If we do not use all of these chemical compounds, they are converted into fats to be stored for later use.
Each of us processes and breaks down calories and food components in our way. How calories are processed depends on several factors. Height, weight, age, gender, physical activity—all of this will determine the way calories are used for energy or stored as fat. The three main things to consider are:
- Basal metabolic rate
- Physical activity
- Thermal effect of food
Your basal metabolic rate, or BMR, is one of the most crucial things to keep in mind for determining how calories work. It accounts for about 60-70 percent of the calories used on any given day. You can calculate your BMR using what is called the Harris-Benedict Formula. A simple example of how the Harris-Benedict Formula works looks like this:
- Adult male: 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years)
- Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)
Types of calories
Calories come in different forms. Some foods contain calories that are easily burned by our metabolism, and other foods contain calories that tend to stay with us. We need to pay attention to the number of calories as much as the sources of the calories.
Some foods are considered high-calorie foods. These foods contain dense quantities of calories per serving size. Oils, butter, fried foods, and sugary foods are high-calorie foods.
This said, not all high-calorie foods are in the category of junk food. Avocados, quinoa, olive oil, and whole grains are all high-calorie foods. What makes them different is the nutritional value that comes with these foods. This can be weighed against the actual calorie content. Another high-calorie food is dried fruits. This means dried fruits are packed with available energy.
Low-calorie foods have a low quantity of calories per serving size. Fruits and vegetables tend to have low-calorie counts. Two cups of shredded romaine lettuce, for example, contain only 16 calories. The same amount of spinach also contains only 16 calories. Oranges, although sweet and packed with natural sugar, have about 70 calories.
These are foods that contain calories but no real nutritional content. Things like fats and added processed sugars are empty calories. These foods provide calories that are not offset by anything of any value. Some foods that have empty calories are natural, like butter, shortening, and fats from some meats.
By far, the most dangerous empty-calorie foods and beverages are junk foods. Things like soda pop, pizza, processed meats, and cheeses are all loaded with calories but have no nutritional value. The problem with these kinds of empty-calorie foods is that the calories provide little to no benefit in terms of usable energy, but store calories in the body and lead to substantial weight gain.
Importance of knowing about calories
As we said at the outset, calories are units of energy. This is the energy your body needs to fuel your metabolism and all bodily functions. Proteins, carbohydrates, fats, and sugars all contain the energy your body needs to keep you alive. Even the basic processes of breathing, maintaining a heartbeat, and digesting food require energy.
Your body converts things like proteins into amino acids that can then be used in your body. This process requires energy that comes in the form of calories from the foods you eat. The number of calories you need comes down to a combination of your own metabolic rate and your level of energy expenditure. From this, you can determine the kinds of foods you should eat and what kinds of foods you should cut down on or eliminate.
When we consume more calories than we burn, we retain calories and store them up. This is where the problem of weight gain comes into the equation. Once we begin to store calories, it can become difficult to burn the excess.
Recommended daily calories
The calories need of an average person are in the below example:
- Men: 150 pounds - 2400 sedentary. 2900 active. 3400 very active.
- Women: 125 pounds - 1900 sedentary. 2100 active. 2300 very active.
- Children: 100 pounds - 2100 sedentary. 2300 active. 2500 very active.
Calories and weight loss
The United States Department of Agriculture defines a healthy diet as one that provides sufficient amounts of essential nutrients from nutrient-dense foods. These are foods that cover all the basic food groups and provide you with enough calories to maintain your metabolic processes.
The best way to lose weight or maintain a healthy weight is to balance your calorie intake against your basal metabolic rate (BMR). There is a simple formula to determine your BMR. The BMR formula for men and women is below:
- Male: (88.4 + 13.4 x weight in kilograms) + (4.8 x height in centimeters) – (5.68 x age)
- Female: (447.6 + 9.25 x weight in kilograms) + (3.10 x height in centimeters) – (4.33 x age)
Once you have figured out your BMR, you simply determine your physical activity level and adjust the figure with your BMR. This formula is below:
- Sedentary: BMR x 1.2
- Lightly active: BMR x 1.375
- Moderately active: BMR x 1.55
- Very active: BMR x 1.725
The final number is the number of calories you need in a day to sustain your metabolism and physical activity level. This is a time, to be honest with yourself. If you spend your days sitting at a desk and do not regularly engage in physical exercise, you fall into the sedentary category. If you are extremely physically active, you are in the very active category.
From this final number, you can calculate how many calories you should consume and how many to avoid. Remember, the simple formula of fewer calories in than calories you burn, and you will have a calorie deficit. This is the best way to use calories as a benchmark for losing or maintaining weight.
What are calories?
A calorie is the amount of energy it takes to raise the temperature of 1 kilogram of water by 1 degree Celsius. This sounds extremely technical but, as we will see, it translates into some understandable features of foods and drinks.
How do calories work?
The number of calories in food is a measure of potential energy. That is, the energy we may derive from the foods we eat but remains unused. A gram of carbohydrates, for example, contains 4 calories. A gram of protein also contains 4 calories. But a gram of fat contains 9 calories. To make sure this potential energy meets our bodily demand, we need to make sure we do not take in more calories than we use. But we also need to make sure we take in enough calories to support the energy demand of the body.
How do calories work with weight?
The best way to lose weight or maintain a healthy weight is to balance your calorie intake against your basal metabolic rate (BMR).
Counting calories is perhaps the tried and true method for controlling weight and for weight loss. This method works with simple math. You take in fewer calories than you burn, and you burn up excess calories in the form of fat. The net result is weight loss.
But many of us do not even know what calories are. Counting calories is not the same as watching specific types of foods. A calorie is really a unit of measure, and the number of calories in the foods we eat can vary considerably. Keeping track of calories can get tricky when we start looking at specific types of foods.
But the good news is that most foods come with calorie counts listed on the labels. We simply need to pay attention to product nutrition information, and we can do some simple math to count calories.
Taking into consideration, the rest of the information in this guide will help you monitor your calories intake. With these simple formulas, you can easily keep track of calories and learn to lose weight or simply maintain a healthy weight.