Energy balance and a healthy lifestyle
Gaining a better understanding of the components and factors that influence energy balance is crucial to maintaining a healthy lifestyle.
Your Total Daily Energy Expenditure (TDEE) is the total amount of calories (kcal) you burn in a day. TDEE is made up of four components:
Basal Metabolic Rate (BMR)
Non-Exercise Activity Thermogenesis (NEAT)
Exercise Activity Thermogenesis (EAT)
Diet-Induced Thermogenesis (DIT) which is usually called the Thermic Effect of Food (TEF)
Basal Metabolic Rate (BMR)
BMR is the largest aspect of TDEE, accounting for somewhere between 60%-65% of the calories you use burn each day. BMR is the minimum amount of energy needed to keep your body functioning and alive at rest.
It’s the energy used to pump blood around your body, keep you breathing, sustain your brain and central nervous system and maintain a stable body temperature. Your weight, lean muscle mass, height, age, gender and genetics all play a role in your BMR.
Non-Exercise Activity Thermogenesis (NEAT)
NEAT is the energy used during activity that isn’t sleeping, eating or intentional exercise such as moving around your home or office, standing, gardening, walking to work, showering, cleaning and even fidgeting.
NEAT is lifestyle dependent and accounts for somewhere between 6%-50% of the calories you burn each day. It’s one of the more easily modifiable components of TDEE. Leaner people tend to stand and walk more each day than those who are overweight.
Exercise Activity Thermogenesis (EAT)
EAT is the energy used in voluntary participation in exercise such as running, weight training, swimming, cycling etc. Like NEAT, EAT is highly modifiable and can be anywhere between 0%-30% of TDEE.
The amount of calories you burn during exercise will depend on the type, duration, intensity and volume of that exercise. As you become fitter and stronger the body becomes more efficient at fuelling that exercise and the amount of calories you burn during that exercise will decrease over time.
EAT is usually a lot lower than people think and for the majority accounts for just 0%-10% of TDEE. Your Sunday morning parkrun will probably only burn around 350 calories - the croissant and latte you have after you finish will be 500 calories - which is why you’ll sometimes hear the phrase “you can’t outrun a bad diet”.
Thermic Effect of Food (TEF)
TEF is the calories your body burns as a result of the digestion, absorption and storage of food. It accounts for around 10% of TDEE on average.
Each micronutrient you eat (protein, fat or carb) has a different TEF which can be expressed as a percentage of the energy provided by that macronutrient: Fat provides 9 calories per gram, and its TEF is 0–3%. Carbohydrate provides 4 calories per gram, and its TEF is 5–10%. Protein also provides 4 calories per gram, but its TEF is 20–30%.
Proteins and complex carbs (such as brown rice) have a higher thermic effect than fats or simple carbs (such as white rice) because your body has to work harder to break them down, thus spending more energy and burning more calories.
Knowing your Total Daily Energy Expenditure (TDEE) is crucial for weight loss because it provides a personalised estimate of your daily calorie needs, accounting for both your Basal Metabolic Rate (BMR) and your activity levels.
Calculating your TDEE
The starting point to knowing your TDEE is calculating your Basal Metabolic Rate (BMR) and one of the most accurate methods (there are several others) of estimating your BMR is the Harris-Benedict formula:
Adult male: 66 + (6.3 x weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years) = BMR
Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years) = BMR
To determine your TDEE (your total daily calorie intake), simply multiply your BMR score by the appropriate activity factor, as follows:
If you are sedentary (little or no exercise) = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) = BMR x 1.375
If you are moderately active (moderate exercise/sports 3-5 days/week) = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) = BMR x 1.9
Here’s an example, for an adult female aged 40 years old, who is 5’ 5” tall (65 inches) and weighs 10 stone (140 pounds):
655 + (4.3 x 140) + (4.7 x 65) – 4.7 x 40) = 655 + 602 + 305.5 – 188 = 1374.5 calories per day
If we assume our example is ‘lightly active’ we multiple her BMR score (1374.5) by 1.375 giving us a TDEE of 1889.9 calories.
So our example adult female needs 1889.9 calories per day in order to maintain her current weight.
If our example wanted to lose weight however, she would need to reduce her daily calorie intake below this TDEE figure, say by 300 - 500 calories a day, through eating less calories or moving more or a combination of the two.