Energy 101 : Understanding Calories, TDEE, and Their Impact On Your Goals.

Welcome to Fitness 101, your trusted resource for fitness fundamentals! In this blog post, we'll clarify calories and explore the concept of Total Daily Energy Expenditure (TDEE). Understanding calories and assessing your TDEE is fundamental to achieving your fitness and nutritional goals, whatever those goals may be. With that in mind, let's work to demystify calories and unlock the key to managing your energy intake!

What’s A Calorie?

The Energy Currency: Calories are units of energy that measure the amount of biochemical “fuel” a food or beverage provides. Your body uses this energy for various functions, including physical activity, maintaining body temperature, and powering essential bodily processes. By definition, one calorie is the energy required to raise the temperature of one gram of water by one degree Celsius. The calories listed on nutrition labels, and the ones we’ll be discussing from this point on, are technically kilo-calories (Kcals), which equal a thousand “small” calories.

Found in Macronutrients: Calories come from three main macronutrients in your diet: carbohydrates (4 calories per gram), proteins (4 calories per gram), and fats (9 calories per gram). Some would include alcohols on this list, but while they do provide calories (about 7 calories per gram), those calories are devoid of nutritional value. Each macronutrient provides a different energy source and affects your body differently.

Caloric Balance and Weight Management: Managing energy intake and expenditure is crucial for maintaining a healthy weight. To lose weight, you must consume fewer calories than you expend; to gain weight, you must ingest more calories than you burn. The amount of calories you burn in a day is known as your total daily energy expenditure, or TDEE.

Assessing Your Total Daily Energy Expenditure (TDEE)

Calculate Your Basal Metabolic Rate (BMR): Your BMR is the number of calories your body needs to perform vital functions at rest, such as breathing, maintaining body temperature, and supporting organ function. Several equations can estimate your BMR, with the Mifflin-St Jeor formula being one of the most accurate.

For Men: (10 X weight in kg) + (6.25 X height in cm) - (5 X age in years) + 5

For Women: (10 X weight in kg) + (6.25 X height in cm) - (5 X age in years) - 161.

Note: Remember to convert inches to centimeters (1 inch = 2.54 cm) and pounds to kilograms (1lb = 2.2kg)

Assess Your Physical Activity Level: To calculate your TDEE accurately, consider your activity level. The more active you are, the higher your TDEE will be. Typical activity levels range between sedentary, lightly active, moderately active, very active, and extremely active.

Activity Multipliers

Sedentary (little or no exercise): BMR x 1.2

Lightly active (light exercise/sports 1-3 days/week): BMR x 1.375

Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55

Very active (challenging exercise/sports 6-7 days/week): BMR x 1.725

Extremely active (intensive exercise, physical job, training twice a day): BMR x 1.9

Calculate Your TDEE: Your TDEE combines your BMR and your activity level. You can use the following formula to estimate your TDEE:

TDEE = BMR x Activity Multiplier

That’s a lot of math… Let’s run an example together!

Imagine that you’re Kyle, a 27-year-old male. You weigh 180lbs (81.65kg) , you’re 6’1 (185.42cm), you workout twice a week and you’re trying to assess your TDEE.

First, you’ll need to calculate your BMR with the Miller St. Jeor formula, which would look like this:

BMR=(10 X 81.65kg) + (6.25 X 185.42cm) - (5 X 27years) + 5 = (816.5) + (1158.875) - (135) + 5 = 1,845.4 Calories Per Day

Since you workout twice per week, we’ll use the “Lightly Active” activity multiplier (1.375) to calculate your TDEE from your BMR.

TDEE = BMR X Activity Factor = 1845.4 Calories Per Day X 1.375 = 2,537.4 Calories Per Day

If you were Kyle, you would burn around 1850 calories per day without exercise, and your exercise regimen brings that expenditure up to around 2540 calories. If you could eat that many calories each day, your weight would stay the same, while eating more or less would result in weight gain or weight loss, respectively.

Next Steps and Closing Thoughts

Once you know your TDEE, you can set goals for weight loss, maintenance, or muscle gain. To lose weight, create a slight calorie deficit by consuming fewer calories than your TDEE. For muscle gain, you should aim for a slight calorie surplus. We’ll cover both of these processes in depth via later blog posts, but once you know how many calories you burn in a day, you’ve set a solid foundation for future success. By learning how to balance your calorie intake and expenditure, you can take control of your weight, your health, and make informed decisions about your diet and exercise routine!

With this fitness fundamental in hand, you’re well on your way toward a healthier, more energized you!