Calorie requirements

What are Calories?

So what are calories, how do we process energy and are all calories the same?
What are Calories and Kilojoules?

Calories and kilojoules are both units of measurement that are used to describe the same thing. They measure the energy in food. One calorie is equal to 4.18 kilojoules. You will often see the symbol kJs when the energy is represented in kilojoules or kcal if it’s calories.

How do you Determine Your Daily Calories?

Daily calorie requirements are subject as they are based on an estimate of activity levels. For this reason, they are best calculated by a nutritionist so feel free to book in for a free consultation. Should you choose to make a rough estimate yourself the formula used in Australia is the Harris-Benedict Equation which provides an estimate of the Basal Metabolic rate and then multiplies this by an estimate of your activity factor. This arrives at your total calorie requirement.

Please note that the equation varies for men and women.

Female Basal Metabolic Rate (BMR)

Calculating the BMR for an Australian female involves a calculation that uses age, weight, and height to obtain an estimate of Basal Metabolic Rate (BMR) This is the number of calories the body needs at rest.

Once the BMR is reached, that amount is multiplied by an activity factor to estimate total daily calorie needs.

Here’s a step-by-step guide:

1. Calculate Basal Metabolic Rate (BMR):
   • For women: BMR = 655 + (9.6 × weight in kg) + (1.8 × height in cm) – (4.7 × age in years)
2. Determine Activity Level:
   • Sedentary (little or no exercise): BMR × 1.2
   • Lightly active (light exercise/sports 1-3 days/week): BMR × 1.375
   • Moderately active (moderate exercise/sports 3-5 days/week): BMR × 1.55
   • Very active (hard exercise/sports 6-7 days a week): BMR × 1.725
   • Extremely active (very hard exercise/sports & physical job or 2x training): BMR × 1.9
3. Calculate Total Daily Calorie Needs:
   • Total Daily Calorie Needs = BMR × Activity Level

Male Basal Metabolic Rate (BMR)

Macro and micronutrients, antioxidants, probiotics, prebiotics, fiber, and polyphenols all play a crucial part in ensuring a healthy balanced diet, that nourishes the body. Considering calorie requirements in isolation might lead to a deficient diet that only meets the basic energy needs without addressing broader nutritional needs.

1. Determine Activity Level:
   • Sedentary (little or no exercise): BMR × 1.2
   • Lightly active (light exercise/sports 1-3 days/week): BMR × 1.375
   • Moderately active (moderate exercise/sports 3-5 days/week): BMR × 1.55
   • Very active (hard exercise/sports 6-7 days a week): BMR × 1.725
   • Extremely active (very hard exercise/sports & physical job or 2x training): BMR × 1.9
2. Calculate Total Daily Calorie Needs:
   • Total Daily Calorie Needs = BMR × Activity Level
3. Calculate Basal Metabolic Rate (BMR):
   • For men: BMR = 66 + (13.7 × weight in kg) + (5 × height in cm) – (6.8 × age in years)

Calorie Surplus

When we consume more calories than we require in a day we are said to have a calorie surplus. This surplus means our body will store the energy for future use. We will see this as a rising number on the scales.

Regardless of whether the calorie surplus stems from chocolate, rice, stir-fried vegetables, or apple pie, the key point remains constant. A calorie serves as a measure of the energy a particular food supplies upon consumption and metabolism by the body. All foods undergo breakdown into glucose, amino acids, or lipids. As units of energy, calories must be used or appropriate accounting by the body.

• Carbohydrates: Found in foods like rice and sweets (chocolate, apple pie), carbohydrates are broken down into glucose, which is a primary source of energy for the body.
• Proteins: Found in foods like stir-fried vegetables, proteins are broken down into amino acids. Amino acids play a crucial role in various bodily functions, including the building and repair of tissues.
• Fats: Present in foods like chocolate and some pie crusts, lipids (fats) are broken down into fatty acids. Fats serve as an energy reserve and are involved in various physiological processes.

The body processes and utilises energy from diverse food sources in a comparable manner. It will use or store calories based on immediate needs. This fundamental concept is crucial for comprehending nutrition and adopting a well-balanced, healthy diet that avoids surplus calories and prevents weight gain.

Calorie Deficit

A calorie deficit arises when the daily calorie intake falls below the required amount for maintenance. In a calorie deficit, weight loss is likely as the body taps into stored energy to compensate for the shortfall. However, it’s important to be cautious and ensure that, even in a deficit, one does not fall below the Recommended Daily Intake (RDI) to maintain essential nutrient levels.

Care should be taken when you are in a calorie deficit not to be consuming under the recommended RDI protein requirements. Consuming under the RDI whilst in a calorie deficit can lead to muscle catabolism which can lead to poorer metabolic outcomes in the long term.

Conclusion

Having an idea of your daily calorie requirements is a handy way to ensure that you maintain a balanced calorie input for your physical needs. This being said calories are only one part of the health equation.

A diet that helps you feel better each day whilst achieving your personal goals can be designed by Julie, your Nutritionist at Positive Nutrition. Book in for her 6 Week Intensive Kickstart Plan.

FAQ Calorie Requirements