Calories In Vs Calories out

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Written By Cameron Johnson

Weight Management explained

 

You may have heard the idea that weight management is all about calories in vs calories out. This simple concept is the foundation of weight management: if you consume more calories than you burn, you gain weight; if you burn more than you consume, you lose weight. However, while the concept sounds straightforward, many factors influence how our bodies manage calories, including metabolic rate, physical activity, and even hormones

Calories in

We need energy for our body to function, both at rest and for movement. Calories are provided by three macronutrients and alcohol.

Carbohydrates:

Carbohydrates are sugar molecules either by themselves (glucose, fructose, and galactose) paired with one other sugar molecule (sucrose, lactose or maltose) or paired with multiple other sugar molecules (starch, glycogen, cellulose, chitin, pectin and agar).

All carbohydrates provide four calories per gram if your body is able to break it down fully.

Protein:

Proteins are made of smaller units called amino acids. There are 20 amino acids in our body. Nine of them are called essential because our body is not able to make them so they must come from your diet. The 11 others can still be obtained from your diet but your body can make them if you are deficient. 

All protein provides four calories per gram if your body utilizes them for energy instead of other purposes. 

Fats:

Fats are made of small units called fatty acids. They are made up of a chain of carbon atoms with hydrogen atoms attached, and it usually has an "acid" group at one end.  There are three categories of fatty acids

  1. Saturated fats

  2. Monounsaturated fats

  3. Polyunsaturated fats. 

The differences between these is how many double bonds there are inside the carbon chain. Saturated fats have no double bonds, Monounsaturated fats have 1 double bond and polyunsaturated fats have multiple double bonds. 

An easy way to identify what type of fat it is is the consistency at room temperature. Saturated fats are solid at room temperature. Unsaturated fats are liquid at room temperature. 

All fats provide nine calories per gram making this the most dense form of energy intake.

Alcohol:

Alcohol can also be broken down by the body and utilized for energy. 

Alcohol provides seven calories per gram. 

Calories Out

We can break down how your body utilizes energy into four main categories.

Resting metabolic rate:

Your resting metabolic rate is how many calories your body utilizes to simply stay alive. This is the energy you would burn through if you just laid still all day long. It includes the energy needed for your heart to beat, for you to breathe, for your brain to communicate with your body, for chemical reactions to take place, and any other function for you to simply stay alive. 

This number can change depending on your body size, your body composition (muscle requires more calories to maintain than fat tissue), your hormone levels such as thyroid, testosterone, estrogen, growth hormone etc, external temperature and many other factors. 

Exercise Activity Thermogenesis (EAT)

This is a fancy phrase for how many calories you burn with planned exercise such as lifting weights, going for a walk or jog, or anything else that you plan that also gets your heart rate up. The amount of calories burned through exercise depends on the duration, intensity, and type of activity. 

Non-exercise Activity Thermogenesis (NEAT)

This is a fancy way of saying the day to day things we do without much thought. Examples include sitting at a desk at work, walking around the grocery store, walking up the stairs, cleaning your home, or playing with your kids or grandkids. It is our general activity level throughout the day. NEAT can vary greatly between individuals and is influenced by factors like job type (e.g., desk job vs. a job that requires physical movement) and personal habits.

Thermic Effect of Food:

Believe it or not our body uses energy to digest, absorb and metabolize the food that you eat. So some of the calories that you eat are used in just breaking down foods. Not all foods require the same amount of energy though. 

Carbohydrates: between 5-10% of the calories in carbohydrates are used to break it down.

Protein: between 20-30% of the calories provided by protein are used to break it down.

Fats: between 0-3% of calories provided by fats are used to break down and store fats.

As you decrease or increase the calories from these different macronutrients your metabolism energy needs change.

Tracking calories in vs out

Calories In:

It can be surprising how many calories are in different foods. There are many apps out there to help you track amount of calories you are eating such as my fitness pal.

Tracking for long periods of time can be daunting and isn’t always necessary. It can be beneficial to track what you eat for shorter periods of time, like a day or a week, to help identify areas where you may be eating excess calories without noticing. Prepackaged processed foods and preprepared foods can have a shocking amount of calories in them.

You shouldn’t feel the need to eliminate all calorie dense foods if you don’t want to, but be aware of how much you are consuming and keep it to a reasonable amount.

Calories out

Resting metabolic rate can easily be measured with a simple breath test. During the test you sit comfortably in a chair with your nose plugged and breath through a hose while we measure the oxygen and carbon dioxide coming from your lungs. This information will tell us how many calories you are burning while at rest. The test takes about 10-15 minutes to complete.

Exercise Activity Thermogenesis (EAT)

There are many apps to help track your exercise.

The most important thing is to find one that works for your workout goals. If you don’t have any specific exercise goals a great place to start is the recommendation from the American Heart Association:

  • Get at least 150 minutes per week of moderate-intensity aerobic activity or 75 minutes per week of vigorous aerobic activity, or a combination of both, preferably spread throughout the week.

  • Add moderate- to high-intensity muscle-strengthening activity (such as resistance or weights) on at least 2 days per week.

Non-Exercise Activity Thermogenesis (NEAT)

A common method of measuring your daily activity is a step tracker. An easy beginning target to aim for is 7,000 steps per day, when that becomes easy aim for 10,000 steps per day.

Don’t forget to include non-trackable activities as well.

  • Take the stairs instead of the elevator

  • Park at the far end of a parking lot

  • Set limits on scrolling apps such as facebook, instagram, X or Tiktok.

  • Do more things that you enjoy doing.

Thermic Effect of Food

There isn’t a good, easy way to measure the thermic effect of food. Whether your goal is to decrease, maintain or increase weight, ideally you should prioritize getting adequate protein. Protein requires more energy to digest if your goal is to lose weight, but it is also vitally important to maintain lean mass and improve the satiety of a meal.

Summary

The concept of calories in vs. calories out ultimately comes down to balance. To maintain your weight, the number of calories you consume (calories in) should be roughly equal to the number of calories your body burns (calories out) through RMR, physical activity (both exercise and NEAT), TEF, and other physiological processes.

  • If you consume more calories than you burn, the excess energy is stored as fat, leading to weight gain.

  • If you burn more calories than you consume, your body will tap into fat stores for energy, leading to weight loss.

However, the process is more complex than just a simple math equation. Factors like metabolic rate, the type and intensity of exercise, NEAT, food choices, and hormonal influences all affect how your body processes calories.

Prioritizing nutrient-dense foods, staying active throughout the day, managing stress, and getting adequate sleep can help create a more sustainable and healthy lifestyle.

Ultimately, weight management isn't just about restricting calories—it's about creating a balanced, healthy environment for your body to thrive in.

 

References

 
 
Cameron Johnson
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