Energy and Body Mass

If looking to remain at the current weight, the correct amount of energy is being consumed.

When energy intake exceeds energy expenditure, body mass increases.

When energy intake is less than energy expenditure, body mass decreases.

Energy intake: all food and drink consumed. Energy expenditure: basal metabolic rate, training and competition demands, activities of daily living and the energy required to digest food. Note that body mass can fluctuate daily due to changes in hydration, muscle fuelling, gut weight and in females, the menstrual cycle.

Energy is obtained from the foods we eat and fluids we d and is measured in units of kilocalories (kcal) or kilojoules (kJ). We all require energy to:

Sustain organ health and function (basal metabolic rate)

Grow and develop

Digest and absorb the food we consume Perform daily tasks and sustain training demands

Energy is only obtained from the ‘macronutrients’ (carbohydrates, protein, and fat), but ‘micronutrients’ (vitamins and minerals) are essential to generate usable energy. Determining how much energy is needed is difficult, as it is dictated by many factors, such as:

Basal metabolic rate

Muscle mass and bone mass

General daily activity levels (e.g. cleaning / gardening / walking)

Exercise intensity and duration

Calories per macronutrient: (k l/ )

Carbohydrates

Protein Fats

4 4 9

Energy requirements vary greatly from person to person and will naturally vary from day to day depending on training and activity levels. Therefore, there is no one kcal intake suitable for all individuals.