Topic 5- Energy Flashcards
- How is energy expenditure fuelled?
By the macro nutrients
- If every is not used what happens?
It will be stored as fat in fat cells
- What does accumulation of excess fat lead to?
Is a health risk and can lead to atherosclerosis, obesity, heart disease. Excess fat located around the abdominal organs leading to cantal adiposity in the most serious risk
- Are all three macronutrients converted to fat in excess?
Yes
- What is the first energy source used?
Carbs. Proteins is usually directed to structural use and dietary fat is stored first
- What macronutrient requires the easiest metabolic steps to be converted to fat?
Dietary fat is the easiest. Thus reducing fat usually has the best effect in reducing body fat
- How can the energy content of foods be determined?
Bomb calorimeter- burns a food into CO2 and H2O and measures the energy released
- How dies the body gain energy?
Though digestion and absorption, nutrients are broken down into four groups of molecules that can enter the cellular energy metabolic pathways for energy. (monosaccharides, amino acids, glycerol and fatty acids)
- What are the 4 groups of molecules that can enter cellular energy metabolic pathways?
monosaccharides, amino acids, glycerol and fatty acids
- What will happen in daily dietary energy intake is balanced by energy output?
Weight will remain the same
basal metabolism + physical activity + DIT + adaptive thermogenesis
- How can people adjust energy balance?
Through food intake or exercise levels
- Why does appetite exist?
It exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs
- How is appetite regulated (simple)?
By close interplay (nerves and chemicals) between the digest tract, adipose tissue and the brain
- What is decreased desire to eat termed as?
Anorexia
- What is increased desire to eat termed as?
polyphagia or hyperphagia
What is the main regulatory organ for appetite?
The hypothalamus- It senses external stimuli though a number of hormones such as:
- Leptin
- Ghrelin
- PYY
- Orexin
- CCK
- What are orexigenic hormones and anorexigenic hormone?
Orexigenic: They increase hunger and therefore enhance food consumption (gherkin, orexin or neuropeptide)
Anorexigenic: Decrease hunger
-What is the most filling macronutrient?
Proteins are ad give an extended feeling of fullness
- How do carbs extend duration of satiety?
They fill the stomach and delay absorption. not all carbs are the same though. High GI carbs are digested and absorbed quickly leading to a return of hunger
- What does fat contain that can lead to over consumption?
Contains positive flavours and orders that stimulate desire to eat
- Ranking of macronutrients on effect of satiety?
Proteins (highest), carbs then fats
- It is understood that much of the regulation of eating if based on another factor besides energy content. What is this?
Mass or volume of food consumed
- What is total energy expenditure made up of?
- Basal metabolic rate: calculated as energy expenditure in a given time for basic body processes
- Physical activity
- Diet and indices thermogenesis (DIT) or thermo effect of food, measure of every used for digestion
- Adaptive thermogenesis of energy spent when ill or in effect climates
- What is basal metabolic rate?
Is calculate as energy expenditure in a given time for basic body processes
- In a moderately active person how much does basal metabolism account for energy expenditure?
60-70%
-The 4 components of energy expenditure and what percentage they make up?
- In general for the moderately active person, basal metabolism accounts for approximately 60-70% of energy expenditure.
- Physical activity generally accounts 15-25% , However in extreme situations of physical activity it can be much higher (eg triatholon, prolonged bike ride or run etc)
- TEF uses approx 10% of energy
- Adapting to altered conditions including illness requires variable energy, but can be as low as zero.
- Ways of calculating basal metabolic rate (BMR)?
All are based on set of equations that consider age, sex and weight
The approx method is:
- 2 kj/kg.hr for males
- 8 kj/kg/hr for females
Eg. BMR = 3.8 x 51 x 24(hours) = 4696.8
- What unit is BMR expressed as?
KJ per hour or day
- What are some factors that will effect BMR?
- Age
- Height
- body composition
- Hormones
- Smoking
- Why is it that the greater the wight of a person the more total requires but less energy per kg of body weight (therefore lower BMI)?
Generally the larger person is carrying more fat cells which use only small amounts of energy compared with other cells
- What is physical activity a measure of?
Measure of energy spent on any physical movement
-Methods for determining energy spent exercising ?
Usual method is to use table of energy expenditure for specific physical activity categories, for different body weight combined with daily diaries of time in each activity
A more simple method in to cluster activities according to intensity and determining a physical activity level (PAL) factor fr each intensity and gender - These factors when multiplied by BMR give the toal estimated energy requirements (EER)
- What is Thermic effect of food (TEF or DIT)?
It is the energy required for digestion and absorption of food. Usually ignored in the energy expenditure calculation due to its small and viable contribution.
TEF is difficult to determine but is usually given the value of 10% of the value of food energy consumed or 10% of physical activity
Quite often TEF contribution is ignored as it is often small and difficult to measure.
2 simple methods which give approximate answers are
Calculate 10% of energy intake from food (ie. the more food eaten, the more energy to digest it).
Use 10% of energy expenditure in exercise, this is only a very approximate way to determine TEF.
- What is body composition made up of (two basic components)?
Fat and lean tissue
- When considering body weight as an indicator for health a number of measurement should be investigated. What are they?
- BMI
- Waist : Hip ratio
- Body fat level as determined by a skin-fold test
- What is the BMI formula?
BMI = weight(kg) / height^2 (m)
- What is BMI used as?
A convenient relationship between height, weight and composition, but ignores body composition
- BMI ranges?
BMI < 18,5 = underweight
BMI 18.5-24.9 = regarded as normal
BMI 25- 29.9 = overweight
BMI > 30 = obese
- What is waist : hip ratio?
This gives a measure of the amount of fat deposition around the waist thermion central adiposity of abdominal fat
waist : hip = waist (cm) / hip (cm)
For males a ration greater than 0.9 is unhealthy and for female a ratio greater than 0.8 is unhealthy
As it is central adiposity (internal abdominal visceral fat) that is the greatest health risk, we need to have a measure to determine relative risk. This is done either by measuring waist circumference alone and comparing to tables of known risk or comparing waist circumference to hip circumference and determining a ratio. Due to gender body shape differences, the healthy and unhealthy rangers for men and women differ.
- What is fat needed for?
- Energy reserve
- Organ protection
- Insulation
- Nerve function
- Hormone production
- Cell structure
- What can excess abdominal fat lead to?
May result in elevated blood lipid levels leading to atherosclerosis, hypertension, cardiovascular disease, stroke an diabetes.
Excess body fat and the following are all common: gall bladder disease, liver disease, respiratory problems, gout, varicose veins ect.
- What can a BMI too low lead to?
A low BMI is also associated with poor health. Potential problems include pro nutrient levels, insufficient energy intake, immunological dysfunction, psychological disorders and infertility
Diabetes
- Diabetes is three times more likely in an obese person
- Abdominal fat calls become highly insulin resistant
- Insulin resistance leads to elevated blood glucose levels
- Occure in middle to old ages and can be termed non- insulin dependant diabetes mettlitis (NIDDM) or type 2 diabetes)
- Many complications lead to death
Cancers
- Strongest like between cancer and weight occurs with morbidly obese women
- Potention reason is the adipose tissue n the major site of oestrogen production and hight oestrogen levels are associated with reproductive cancers
- How to determine is a person is of healthy weight?
Need to know total fat about and location.
Therefore we consider weight, SMI, waist:hip, body fat levels and body fat location.
Acceptable levels of body fat for men is 15-25% and for females it is 25-35%
