Let’s talk about the three main categories of macronutrients – fat, protein, and carbohydrates. These are the nutrients your body needs in large quantities – for energy and maintenance of cells in the body.
The fundamental principle of all weight loss is a deficit in calories. You’ve go to burn more calories than you eat. Your body’s base metabolic needs and physical activity burn the calories you take in. So it’s simple really – burn more than you eat (or more accurately what is simpler is to eat less than your body will burn). And we all know our food contains calories, but what is a calorie specifically?
What is a calorie? To keep it simple, it is the energy potential in a food item. And specifically calories measure heat. Your body needs calories – because your body needs energy – and in food that’s how energy is measured. A calorie is a unit of energy. The proper scientific nomenclature is the kilocalorie – and it represents the amount of energy in a substance that when burned, can raise the temperature of water.
So a calorie is a way to measure the energy in food – and our bodies store excess energy as body fat. Our food contains calories – but different types of food have different caloric amounts. How do we determine this? We can figure this out by understanding which macrocnutrients our foods contain.
The number of calories present in 1 gram of:
- Fat: 9 calories
- Protein: 4 calories
- Carbohydrates: 4 calories
Macronutrients are required in large quantities and intake is measured in grams or ounces (there are 454 grams in a pound.)
Alcohol is not a macronutrient but does contain 7 calories per gram – so if you are trying to lose weight limiting alcohol intake is important.
Macronutrients, commonly referred to as “macros”, are the nutrients that our bodies need in large quantities to provide energy for our physiological systems and to provide the raw structural materials needed for body maintenance. Protein, fat, and carbohydrates are macronutrients. Protein is the primary structural and functional element of every cell in our bodies. It is needed for growth and development (such as building muscle), general tissue repair, proper function of our immune system, and many other things. Protein is considered an essential nutrient – your body must acquire protein through food to survive. Protein is multi-purpose, and can even serve as a source of energy, when needed, through a process called gluconeogensis. But our bodies prefer other sources for raw energy – and that takes us to the next major macronutrient. Carbohydrates, or carbs, consist of sugars and starches and are an important source of energy that is easy for the body to use. Our bodies need lots of energy for powering everything from our brain function to muscular contraction. Carbohydrates are not considered an essential nutrient (as we mentioned earlier, your body can derive energy from protein – if it had to – or fat), but due to their abundance they make up a large portion of the average diet regardless.
Fat does not just give food great taste – it’s also an important source of energy. And certain kinds of fats are essential (omega 3 and omega 6 fatty acids) – meaning they are required by the body but can’t be manufactured by the body. We can only get these nutrients through our diet.
Fiber is also an important part of your diet – but it doesn’t contain calories. Fiber is found in grains, fruits, vegetables, and seeds. It includes the parts of plant foods your body can’t digest or absorb. Fiber, also known as roughage or bulk, passes relatively intact through your stomach and digestive tract. As such, it aids in digestion, helps provide a feeling of fullness (so you eat less), can slow the absorption of sugars and help to stabilize blood sugar levels, and is associated with a decreased risk of heart disease and certain types of cancer. Fiber doesn’t contribute calories to your body, but is still an important part of a healthy diet.
Water is also a nutrient essential for survival – but contains 0 calories.
You will often hear about “macros” or “macro counting” in popular weight loss methods. Counting macros is a convenient way to approximate your total caloric intake and also to ensure you are getting the right raw materials your body needs. This is a popular technique for weight loss, body recomposition, or body building diets – which often require specific amounts of protein.
Are all calories created equal? In theory, yes – but protein is renowned for its above average thermic effect. The thermic effect of food is the caloric cost of digesting and processing that food. The act of digesting protein burns a significant amount of calories – as much as 20% or 30% of the caloric value of the protein itself. This is much more than carbs (up to 15%) or fats (around 5%). The fact that proteins are satiating (make you feel full), digest slowly, and burn significant calories while they digest – make them an excellent cornerstone of a healthy diet or weight loss plan. This is why you often find an emphasis placed on protein intake for dieters.
Daily calorie recommendations – How many calories do you need?
How many calories do you need in a day? It will vary based on the individual. The important criteria include the person’s age, sex, height, weight, and level of physical activity.
Regarding levels of physical activity the US government definitions are as follows:
- Sedentary – a lifestyle that includes only the light physical activity associated with typical day-to-day life.
- Moderately active – a lifestyle that includes physical activity equivalent to walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to
the light physical activity associated with typical day-to-day life.
- Active – a lifestyle that includes physical activity equivalent to
walking more than 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life.
This information is provided via the Dietary Guidelines for Americans 2015-2020:
|76 and up||2,000||2,200||2,400|
|76 and up||1,600||1,800||2,000|
You are probably familiar with the nutritional label present on all food items produced and sold in the US. This is a mandate from Food and Drug Administration (FDA), a division fo the US government. On this label a “% Daily Value” (or DV) is present. DVs are based on a 2,000-calorie diet for healthy adults.
- “Each Gram of Protein & Carbohydrates Contains How Many Kilocalories? | Healthy Eating | SF Gate.”
- Nutrition, “Labeling & Nutrition – Changes to the Nutrition Facts Label.”
- “How to Add More Fiber to Your Diet.”
- “Vitamins & Minerals: Are You Getting What You Need?”
- “Estimated Calorie Needs per Day by Age, Gender, and Physical Activity Level.”
- Dietary Guidelines for Americans 2015-2020, Eighth Edition
- Appendix 2. Estimated Calorie Needs per Day, by Age, Sex, and Physical Activity Level