How Platify Works Out Your Daily Energy Needs

Platify calculates your daily energy needs by estimating your Total Daily Energy Expenditure (TDEE) using the scientifically validated Mifflin-St Jeor equation, aligning with the NHMRC standard reference intake of 8,700 kilojoules per day for the average Australian adult.

What is total daily energy expenditure?

Total Daily Energy Expenditure (TDEE) represents the cumulative energy your body burns in a 24-hour period. We measure this energy in kilojoules or calories. A kilojoule is a unit of measurement used to represent the energy content in food and drink.

According to the Victorian Better Health Channel, the average Australian adult consumes approximately 8,700 kilojoules of energy per day to maintain weight. However, your personal energy needs are highly individual. Your TDEE is comprised of three main components: your basal metabolic rate, the thermic effect of food, and energy expended during physical activity.

To understand energy balance, we must look at both energy intake and energy expenditure. The Australian Dietary Guidelines state that an adult's estimated daily energy requirements are determined based on their age, gender, body mass index, reference weight, and physical activity level. Balancing these factors ensures your body receives the correct amount of fuel.

How does basal metabolic rate work?

Basal metabolic rate (BMR) refers to the speed at which the body expends energy while at rest. According to Healthdirect Australia, an individual's basal metabolic rate is influenced by their genetics, sex, age, health status, and weight. It represents the minimum speed at which the body expends energy to maintain vital organ homeostasis.

Your BMR represents the total number of calories the body burns per unit of time while at rest to keep your heart beating, lungs inflating, and brain functioning. According to the Better Health Channel, an individual's basal metabolic rate is largely determined by their total lean mass, particularly muscle mass. This means building muscle tissue naturally increases your resting energy expenditure.

BMR is not static and changes throughout your life. For instance, data published in ScienceDirect indicates that an individual's basal metabolic rate increases by approximately 30% over the course of pregnancy to support fetal development. This demonstrates how dynamic our metabolic baseline can be during major physiological changes.

Why does Platify use the Mifflin St Jeor equation?

To calculate your resting energy expenditure, our platform utilises the Mifflin-St Jeor equation. The Academy of Nutrition and Dietetics (formerly the American Dietetic Association) recommends the Mifflin-St Jeor equation as a reliable method for estimating energy needs, particularly for individuals with obesity. It provides a highly accurate starting point for tailoring your nutrition plan.

The Mifflin-St Jeor equation calculates resting energy expenditure for males using weight, height, and age: REE (males) = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) + 5. A corresponding formula is adjusted for females to account for differences in body composition.

Research published in a 2020 PubMed Central review confirms that simplifying the predictive formula and separating it by biological sex does not negatively impact its predictive value for resting energy expenditure. This allows the platform to maintain high mathematical accuracy without requiring complex, invasive body fat measurements.

How does activity level affect energy needs?

Physical activity is the single largest variable driving differences in daily energy requirements. A study in The American Journal of Clinical Nutrition highlights that differences in physical activity are the greatest source of variation in energy requirements both within and between individuals.

Moving your body regularly is also essential for long-term health. The World Health Organization notes that people who do not engage in sufficient physical activity face a 20% to 30% increased risk of death compared to those who are sufficiently active. This highlights the importance of incorporating movement into your daily routine.

Energy expenditure patterns also change as we grow. Research in Paediatric Respiratory Reviews shows that activity energy expenditure increases from 20% of total energy expenditure at age one to approximately 35% at age 18. Physical activity levels also significantly affect the daily energy needs of patients managing chronic health conditions.

How many calories do I need per day?

Your personal daily target is calculated using your age, sex, height, weight, and physical activity multiplier. The Eat For Health daily energy requirements calculator estimates the amount of energy needed for optimal health based on essential bodily functions like breathing and circulating blood.

While reducing energy intake can support weight management, it is vital to avoid extreme restriction. Harvard Health Publishing advises that daily calorie intake should not fall below 1,200 calories for women or 1,500 calories for men unless supervised by a health professional. Eating too little can compromise your nutritional intake and energy levels.

Our coaching app translates these energy targets into practical food group serves based on the Australian Dietary Guidelines. By using Eat For Health calculators, the platform estimates your daily nutrient requirements and recommends the daily number of serves from the five food groups to ensure nutritional adequacy.

How does weight loss change your energy needs?

As you lose weight, your total daily energy expenditure naturally declines. A study published in Obesity shows that total daily energy expenditure declines during weight loss due to decreases in both resting energy expenditure and physical activity energy expenditure. This is a normal physiological process.

This reduction in metabolic rate means that your energy targets must update as your body mass changes. The Food and Agriculture Organization (FAO) emphasises that habitual physical activity and body weight remain the primary factors driving the variation in energy requirements among adult populations.

To support a sustainable journey, our platform periodically recalculates your targets. This ensures your energy budget aligns with your current body mass and activity levels, helping you avoid weight plateaus while nourishing your body with the essential nutrients it needs for long-term vitality.