Energy - EoNS Flashcards
Where does energy come from?
Plants trap energy from the sun and convert it to chemical energy (photosynthesis)
Animals eat the plants and obtain chemical energy
We eat the plants and animals which contain sorted energy in the nutrients;
•Fat
•Carbohydrate
•Protein
Why do we need energy?
To maintain vital bodily function
◦Breathing (respiration)
◦Heart-beat (circulatory system)
◦Keeping warm (thermoregulation)
◦Protein synthesis (tissue repair, enzymes, cell structures)
What is a positive energy balance and what does it result in?
Positive energy balance is when the energy intake exceeds expenditure (over time) which will result in being overweight/obesity
What biological factors result in a positive energy balance?
Ghrelin (stimulates food intake)
Leptin (supresses food intake)
Reduced energy expenditure following weight loss
What are the dietary factors which promote a positive energy balance?
- Energy density: greater kcal provision
- Ultra processed foods: greater weight gain vs unprocessed. UPFs may also lead to overeating
- Caloric availability of food; total kcals in food versus the amount of useable kcals in food. Food processing can impact useable energy in foods e.g corn on the cob versus cornbread.
What are the environmental factors which promote a positive energy balance?
- Increased availability of energy dense foods
- Expansion of fast food outlets
- Transport accessibility
4.Sedentary living/occupational shifts - Technological advancement
What is a negative energy balance and what can it result in?
Prolonged insufficient intake of energy and nutrients not meeting individual needs which can result in malnutrition
What factors result in a negative energy balance?
Disease state/clinical status – increased energy expenditure (e.g. COPD)
Reduced food intake:
•appetite (medication, mood/desire to eat, etc)
•physical and cognitive functioning
•sensory changes (taste, smell, for example chemotherapy treatment)
•Environment/food availability
How is energy measured?
Kilojoules (KJ) or Megajoules (MJ)
Kilocalories (Kcal) commonly referred to as calories
Why do we need to measure energy balance (with examples)
- Health: estimating energy needs of groups and individuals to provide healthy eating recommendation and monitor health of a population
- Nutrition standards: School meals, hospitals, care homes
- Sport: training and performance of athletes
- Management of clinical conditions: Obesity, Type 2 Diabetes Mellitus
- Disease process: brain injury, surgery, pancreatitis
- Pregnancy and lactation; associated energy needs
How do we determine the energy in food?
A food is burned in a bomb calorimeter; heat released measured by the rise in the temperature of the water.
Kcals can be calculated: 1kcal will raise the temperature of 1kg of water by 10C
What are the Atwater factors for CHO, protein, fat and alcohol?
◦Carbohydrate 3.75 kcal (16kJ) /g
◦Protein 4.0 kcal (17kJ) /g
◦Fat 9 kcal (37kJ) /g
◦Alcohol 7 kcal (29kJ) /g
Energy intake can be recorded with a food record. How many days should it include and what are the pros and cons?
EI is most accurately assessed by a 4 - 7 day weighed food record. Good indicator of habitual intakes. Not reliant on memory though requires cognitive and writing skills and has a high respondent burden. Eating out limits accuracy.
What is BMR?
Basal metabolic rate (BMR) is the energy expenditure of lying still at rest, awake, in the overnight postabsorptive state
What factors influence BMR?
- age
- body composition
- extremes of environmental temperature
- illness; fever, trauma, stress
5.drugs; caffeine, nicotine, amphetamines
