Where do we get energy?
Where do we get energy?
My recent post about energy drinks mentioned that if the beverage has no calories, how can it have energy?
This post made me remember that not everybody understands or knows where energy comes from or how we define "energy" in the field of nutrition.
In the science of nutrition, we measure energy in the unit of calories. Calories are what the body uses for energy. We get energy from the foods we eat, specifically foods that contain nutrients that have calories or energy. We call these the "energy nutrients."
There are four sources of calories in the diet – and only three are nutrients.
What is a calorie?
A calorie is a unit of energy. Technically the term is "kcal" or "kilocalories," – but in the U.S., people freak out when we use the metric system, so we simplify it to calories.
Scientifically speaking, a calorie is the measure of the amount of energy needed to raise the temperature of 1 gram of water by 1 °C.
What does that mean in real-world nutrition? Not much to most people.
What it does do is allow scientists to determine how many calories are in food. A fancy device called a "bomb calorimeter" assesses the amount of energy in a food.
Some people assume that calories are just known. However, some scientists are doing this behind the scenes getting this information in a database. Then food companies use this database to source their source information.
How Humans Use Calories
Getting back to a "calorie."
There are calories in food and beverages we consume.
There are the calories that humans burn daily to exist -- we need the energy to function daily, hence the reason we consume food.
There are the calories that we burn by doing physical activity. The amount we burn varies based on many factors, including the intensity and type of activity and the person doing the activity.
How many calories we burn by doing activities varies based on many factors. So, it is virtually impossible to say to somebody you burn xx calories doing this activity without considering five things: height, weight, age, sex, and physical activity level.
It is a bit easier to measure the number of calories we consume. But even then, it's not exact. Instead, it is an estimate or an average of foods.
For example, we say a medium apple has about 80 calories. It is an average of multiple measures of apples over time and estimated that it is about 80 calories for a medium apple. However, we could have 50 apples from the same tree, and they could all be different. If we took just four and got the calorie content, we could have them come out at 73 calories, 77 calories, 96 calories, and 84 calories. That would be an average of 82.5 calories between those four apples. So, there is no way to know every single day what every food has.
Back to Energy
But let's get back to "energy." The term calories is also another word for energy in nutrition.
Returning to this statement: There are four sources of calories in the diet – and only three of them are nutrients.
These four sources of calories are:
Carbohydrates
Protein
Fat
Alcohol
Alcohol isn't a nutrient, and not everybody consumes it, but it does have calories independent of carbohydrates.
Carbohydrates contain four calories per gram – from sugar, a piece of fruit, a piece of bread, a carrot, beans, or a chocolate bar. So for each gram of carbohydrate, it provides four calories. Therefore, if something has 12 grams of carbohydrate, it will provide 48 calories from carbohydrate.
Protein also contains four calories per gram – it doesn't matter if it's coming from chicken, beans, broccoli, or protein drink. All sources of protein will have four calories per gram. So, if something has 8 grams of protein, it will provide 32 calories from protein.
Protein and carbohydrates have the same number of calories per gram. Many people are surprised by this. They think sugar or carbohydrates have more calories per gram than protein, but it doesn't.
Fat contains nine calories per gram, so more than twice the calorie content of carbohydrates and protein. Fat is energy dense with more than twice the energy of carbohydrates and protein. Once again, it does not matter the type of fat. Whether coconut oil, olive oil, or omega-3 in salmon, all those fats have nine calories per gram. A food with 3 grams of fat has 27 calories from fat.
Of course, there are healthier fats and not-so-healthy fat, but no matter what, those will have the same number of calories per gram. There is no such thing as "low fat," oil, "low-fat," fat, or even "reduced fat" fat. When you see light oil, it is probably referring to the taste. People are often surprised to learn that light olive oil isn't lower in calories or healthier. Look closely at the label, and it says light-tasting olive oil.
These three nutrients are known as macronutrients (or "macros"). However, it is essential to note that most foods are a combination of at least two if not all three of these nutrients. So, unless we're consuming sugar or straight oil, we're getting a mixture of carbohydrates, protein, and fat in most cases. So, for example, we get carbohydrates, protein, and fats when eating nuts.
Alcohol – A Source of Energy
Alcohol is a source of calories independent of carbohydrates and provides 7 calories/gram. There is not such thing as no calorie alcohol.
Now the fourth source of energy or calories is alcohol. Alcohol is not a nutrient. It is not something humans need to live.
Even if one chooses "low carb," beer or alcohol that advertises as being "low in sugar" or "low in carbohydrates," that doesn't change much for most forms of alcohol. It is marketing. Alcohol by itself has energy; it has calories. Distilled spirits have no carbohydrates, fat, or protein, yet it's still 90-110 calories in a 1½-ounce serving (equivalent to a shot). The amount varies based on the "proof" 80 proof will have fewer calories than 90 proof. Liqueurs will have added sugars, increasing the overall calories (from carbohydrates).
Alcohol has seven calories per gram. There is no way to have a "no calorie" alcohol – it doesn't exist. If a brand or type of alcohol is advertising that it's low calorie, that means it's lower in alcohol content.
Low Energy?
When people say they're "low energy," they may be many reasons. They are tired, have a lot on the calendar, or may even be sick. But in many cases, we can adjust our eating patterns and habits to ensure adequate energy throughout the day.
A common thing I bring up is when people feel tired in midafternoon or even later afternoon, there is low energy, and that's when I encourage people to have a snack.
When it comes to energy drinks, if they have no calories, they cannot possibly have energy in them. So, therefore, I refer to it as a stimulant drink rather than an energy beverage.
Let me know: Did you know that calories are just the unit of energy? It measures how much energy you need, how much energy you consume, and how much energy you burn, all just calories.
