Energy and energy balance Flashcards
what are 5 reasons why the body needs energy?
-physical activity and making muscles move
-body temperature
-bodily functions e.g. heartbeat
-growth and repair of body tissues
-meeting specific needs e.g. pregnancy and illness recovery
what are the 9 factors that affect energy requirements?
-age
-gender
-physical activity
-pregnancy
-illness
-body composition
-hormone imbalance
-thermogenic effect of food
-BMR
why does age influence energy requirements?
-younger children have higher metabolic needs and need more energy than adults
-this is because they are more active and are growing rapidly
-the older we become the less energy we need as there is a reduction in physical activity and lean body mass (everything except fat)
-energy requirements for growth are the biggest in the first 3 months of life at 35%
why does gender influence energy requirements?
-men need more energy than women as they have a larger overall body size and surface area
-larger body size is linked with a greater energy expenditure, larger bodies need more energy to keep them warm
-large muscles and bone need more energy for movement than a smaller body
why does physical activity influence energy needs?
-sedentary lifestyle e.g. office workers, need less energy as they are moving less
-active lifestyle e.g. builders have the largest energy requirements
-some activities use more energy than others because they exercise more muscles and require the body to work hard
why does pregnancy influence energy needs?
-more energy is needed to ensure the healthy growth and development of the fetus, uterus and breast tissue
-this extra energy only amounts to 200kcal in the third trimester only.
-during lactation an extra 400-800 kcal is needed each day to ensure sufficient milk production with the right energy content of the milk
why does illness and disease influence energy requirements?
-if the body has a fever the metabolic rate rises, during the fever the body attempts to reduce the temp by 1 degrees which increases basal metabolic rate by 10%
-fever drains energy stores which is why people lose weight when they are ill
why does body composition influence energy needs?
-lean body tissue (muscle) is more metabolically active and uses more energy than adipose (fatty) tissue
-individuals who have more lean body tissue are more likely to burn off excess energy
why does hormone imbalance influence energy needs?
-hormones help regulate metabolism
-thyroid gland secretes hormones which regulates metabolic processes
-overactive thyroid increases metabolic rate and individuals may need to consume more energy to help this imbalance
-underactive thyroid slows metabolism as the gland doesn’t release enough hormones
what are symptoms of an underactive thyroid?
-weight gain
-depression
-constipation
why does the thermogenic effect of food influence energy needs?
-intake of food stimulates metabolism causing an increase in metabolic rate as the body digests food eaten
-the energy produced as heat is known as the thermogenic effect
-this effect of food is greater with protein and carbohydrate than with fats
-this effect accounts for 10% of energy expenditure daily
what does BMR stand for and what does it mean?
-amount of energy needed in order to maintain functions e.g. heartbeat, breathing and body temp, when the body is totally at rest
-accounts for 75% of energy needs
-young children have a proportionally high BMR to meet demands of growth
-men have higher BMR than women as they have a greater muscle mass
-older adults have a lower BMR as muscle mass decreases
what does EAR stand for?
-estimated average requirements
what is EAR linked to and how is it calculated ?
-all energy requirements are linked to individual basal metabolic rates and their physical activity levels
-EAR=BMR x PAL
what does DRV stand for and what does it mean?
-dietary reference value
-comprised of a series of estimates of the amount pf energy and nutrients needed by different groups of healthy people in the UK population
