Human Energy Balance Eve Nortley Senior Teaching Fellow

Human Energy Balance • Eve Nortley – Senior Teaching Fellow WMS 2009

Aim Provide an overview of human energy balance as a basis for evidenced based clinical practice.

Learning outcomes At the end of this sessions it is intended that participants have had the opportunity to: - • Discuss the key principles involved in human energy balance. • Estimate their own energy intake and expenditure. • Undertake a consultation with a peer based on estimation of BMI, measuring waist circumference and advising a peer appropriately on food intake and physical activity. • Observe reflection-in-action and produce a personal reflection on-action.

What it means to be human!

skull – balanced centrally on top of vertical spine for upright posture Spine – S shaped to act a a spring – absorbing shock during movement Pelvis – short and bowl shaped – accommodates large gluteus maximus muscles Thighs – slope towards knees – keeps knees below centre of gravity Knees – lock when extended creating vertical columns Feet – arched to absorb impact Legs – large giving low centre of gravity

How long do we need to be active for daily …a look at some close relatives

Prof. K. Fox, 1999, British Nutrition Foundation “ The human body has evolved to accommodate vigorous physical activity, and inactivity can be regarded as abnormal, rather than normal. It should not, therefore be surprising that inactivity is associated with ill health”

The energy balance equation + =

What do humans “spend” food energy on? • Metabolic processes to sustain life • Generation of tissue (growth and repair) • Thermoregulation • Involuntary muscle movement • Voluntary muscle movement

Human energy expenditure Has 3 major components in adults: 1. Basal metabolic rate (BMR) / resting metabolic rate (RMR) 2. Thermic effect of food 3. Physical activity

• Basal metabolic rate is minimum amount of energy to sustain life in waking state – measured 12 hrs after meal (RMR is usually used – is BMR +3% steady over 24 hrs – approx 4. 2 k. J / min) • Thermic effect of food – energy used to digest, metabolise, convert and store macronutrients. • Physical activity – thermic effect of exercise, energy used by skeletal muscles during activity. (Gibney, Vorster and Kok 2002)

Human energy expenditure • BMR/RMR 60 - 75% • Thermic effect of food 10% • Physical activity 15 – 40%

The “story” so far….

What affects……. BMR / RMR

What affects BMR? • Body weight • Body composition • Age • Gender • Genetic differences, physiological factors, disease or trauma, pharmacological effects, ambient temperature

Body weight and BMR

Body composition and BMR

Age and BMR

Gender and BMR

Genetic differences, physiological factors, disease or trauma, pharmacological effects, ambient temperature

A quick recap……