If you ever really need proof of how the human body works, find your way to a metabolic chamber. There are about 30 of them in the world and they cost millions of dollars. They use the best technology to measure every ounce of energy consumed or burned.
These cameras allow scientists to better understand diseases that affect the human body, including things like obesity and metabolic disorders. They also definitively answer the question that has been debated for decades: calories. if it matters. And they are the main factor influencing weight gain or loss. The question is whether a “calorie is a calorie” and more about understanding why all calories are not created equal.
No scheduled trips to your nearest metabolic chamber? Don’t worry. We’ll help you understand which foods influence your metabolism and hunger, and how you can make food work for you.
What is a calorie?
We often think of calories as something we eat, but the truth is that a calorie is simply a unit of energy. More specifically, a calorie is the amount of energy required to raise the temperature of one gram of water by one degree Celsius.
What does water temperature have to do with calories in food? Well, scientists determine the amount of calories in a food using a technique that we are all guilty of in the kitchen: they burn it.
This process is called bomb calorimetry. First, you place an ingredient in a sealed stainless steel container surrounded by water. Then, heat is applied to the food until it burns. This chemical reaction generates a ton of heat and slowly warms the surrounding water. The scientists then measure how much the temperature of the water rises to calculate the number of calories in the food.
Although accurate, this process is slowly losing popularity. Today, most of the calories listed by the USDA and FDA are calculated differently. Instead of burning the food, the total amount of calories is determined by adding the calories provided by the individual components of the food. This means determining the amount of energy from protein, carbohydrate, fat, and alcohol.
This method works because the calories in a gram of protein, carbohydrates, fat, and alcohol remain constant. Each macronutrient has the following caloric values:
- 1 gram of protein = 4 calories
- 1 gram of carbohydrates = 4 calories
- 1 gram of fat = 9 calories
- 1 gram of alcohol = 7 calories
This is how you add up the calories in your food. But, that’s not the whole story. As you’re about to discover, macronutrients are metabolized differently, so not all calories are created equal. Some foods (such as protein) burn more calories during digestion, and other foods (such as fiber from carbohydrates) affect hunger and appetite.
Understanding how to balance your diet to give you the right amount of sanity, without letting your hunger run wild, is the key to feeling in control of your diet.
Why Calories Aren’t Equal (And What It Means for Your Meals)
The confusion about calories is less about how many grams are in a particular food after it’s cooked or when it’s in a package, and more about how your body uses those calories once you eat and digest the food.
The human body is the largest machine ever built. You need a certain number of calories to carry out daily functions such as breathing, walking, and thinking. And because your very survival depends on calories, your body processes food differently to help meet all your needs.
To understand how you gain and lose weight, you need to think about energy balance, which is the age-old debate about calories in versus calories out. Although many things can affect energy balance, the type of calories you consume plays a role. That’s why all calories are not created equal.
Your daily metabolic rate is influenced by many things. The three main components are:
- Basal metabolic rate (BMR): This is the amount of energy your body needs to function.
- Thermic effect of food (TEF): This is the amount of energy you burn when you eat.
- exercise and activity: These are the calories you burn with movement and exercise. You can break this down into different categories such as NEAT (lean as move and fidget) and your traditional workouts.
What most people don’t realize is that 65 to 80 percent of the calories you burn every day comes from your basal metabolic rate. Physical activity and the food you eat make up the rest of your metabolism, but that does not mean they are insignificant.
Protein, carbsand fat are metabolized differently. Eating 100 calories of protein is different than eating 100 calories of carbs because protein has a higher thermic effect of food (TEF).
When you eat protein, you can burn up to 30 percent of your calories. In the example above, if you ate 100 calories of protein, approximately 70 calories would reach your body because 30 calories would be burned as a result of the high TEF of the protein.
In other words, the higher the TEF, the more it influences the “calories burned” portion of the equation calories in fewer calories out (because not all of those calories will end up in your body and be stored). Relatively, carbs they have a TEF of only 5 to 10 percent, and fat is usually around 3 to 5 percent.
This is one of the reasons that high-protein diets tend to be associated with weight loss and maintenance. But, it is only part of the story.
The ripple effect of eating more protein
Protein also has a ripple effect on hunger that makes it an excellent foundation for muscle gain and weight loss.
When you eat protein you increase what is called satiety. This means that a protein-rich meal makes you feel fuller and crave less food (i.e., eat Fewer calories).
That’s why high-calorie options (some might consider them empty calories) like fast food or ice cream can leave you hungry just a few hours later. It’s not just the calorie count of these foods. It’s that they don’t meet your body’s needs to control hunger, so you crave more food even when your calorie intake is high. It’s okay to eat these foods once in a while, but they make it harder to stay full.
A protein-rich meal can stimulate the release of a hormone (ghrelin), which helps quell hunger and plays a role in determining how quickly hunger returns after a meal.
When you combine all the benefits, it’s easy to see why eating more calories from dietary protein helps create a caloric deficit. Protein burns more calories (higher TEF) and reduces the “calories in” part of the equation by affecting how much you eat later in the day.
Plus, giving your body the protein it needs to recover from strength training can help you build more muscle mass.
Protein isn’t the only macronutrient that helps curb hunger. Fiber, found in carbohydrates, is also incredibly effective at increasing satiety without adding too many calories. Most fibrous foods are low in energy density, which means you can eat a lot without taking in too many calories.
Learning to eat the foods that keep you full is an easy way to give you more flexibility. The goal of any diet is not to be too restrictive, it is to provide more freedom.
If you focus on making at least half of your plate protein and fiber, you’re more likely to stay full and not overeat.
That way, you still have the ability to eat other foods that aren’t as nutritious. For example, although 100 calories in chicken is different from 100 calories in a candy bar, we’re still talking about 100 calories. If the candy bar doesn’t get you to eat 10 more candy bars, then worrying about those 100 calories is time and stress your mind and body don’t need.
That’s why effective diets, in general, can consist of 80 to 90 percent more nutritious foods (think vegetables, fruits, nuts, seeds, high fiber carbsand protein) and 10 to 20 percent of foods with the least direct health benefits. That’s the kind of balance that will pay off and prevent burnout.
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Adam Bornstein is a New York Times bestselling author and, according to The Huffington Post, “one of the most inspirational sources on all things health and fitness.” An award-winning writer and editor, Bornstein was the Fitness and Nutrition Editor for men’s healtheditorial director of LIVESTRONG.com and columnist for SHAPE, fitness for menand Muscle and fitness. He is also a nutrition and fitness consultant to LeBron James, Cindy Crawford, Lindsey Vonn, and Arnold Schwarzenegger. His work has appeared in dozens of publications, including The New York Times, fast company, ESPN, and G.Q., and appeared on Good Morning America, The Today Show, E! News and The Cheddar.