Body Composition Flashcards
Define body composition.
The relative proportions of protein, fat, water + mineral components in the body that make up total body weight
What are the components of body composition?
Fat free mass (FFM) = 72% water, 21% protein + 7% bone minerals
Fat mass (FM) = 20% water + 80% adipose tissue
What is the difference in body composition between men and women?
Men have more muscle than women whereas women have more fat than men
What are the 2 types of body fat distribution?
- Andoid
2. Gynoid
What are the features of andoid body fat distribution?
Upper body obesity (mostly stomach area)
Higher risk for T2DM, CVD + HTN
Mostly in males
What are the features of gynoid body fat distribution?
Lower body obesity
Harder on hip + knee joints
Found mostly in women
What is another word for body type?
Somatotype
Describe the ectomorph body type.
Lean + angular, long limbs, slim + narrow waist
Weight loss easy
Low levels of body fat
Difficult to gain LBM
Describe the mesomorph body type.
Strong, athletic, muscular with slim hips
Faster metabolism
Gain muscle mass easily
Lose weight easily
Describe the endomorph body type.
Round, short, tapering limbs, larger boned, plump/stocky appearance, round faces, large thighs + hips
Higher body fat
Easily build muscle
Weight loss difficult
What should you consider when measuring and assessing body composition?
How
Practicalities
Patient group
What is a body weight assessment?
Total weight of FFM + FM combined
What is a body composition assessment?
Assessment of varying components of the FFM compared to the FM
What assessment is most common on nutrition screening tools?
BMI/Quetelets index - measure of body weight
What is Body Mass Index (BMI)?
Ratio of weight + height often used to express clinical risk
Mass (kg) / (height(m))^2
What is the Body Mass Index (BMI) that reflects the lowest risk of illness?
18.5-24.9kg/m^2 (23kg/m^2 classed as overweight for Asians)
What are the limitations of measuring Body Mass Index (BMI)?
Doesn’t consider body composition
Should be used in conjunction with other measures e.g. waist circumference
Age + gender independent
Different classifications for Asians + Afro-Carribean’s
How is Body Mass Index (BMI) linked to mortality risk?
Risk increases as BMI declines but also as BMI rises
Why do Asian people have a different ideal BMI to White Caucasian individuals?
Because overall their body composition is lower than that of white people so they should weigh less under normal circumstances
What alternative height measurements can be used to predict BMI without scales or a height measure?
Ulna length
Knee height caliper
Demi span
What does Mid Upper Arm Circumference (MUAC) give you an indication of?
Body weight changes over time (can be used if patient cannot be weighed)
What are the normal values for Mid Upper Arm Circumference (MUAC) and how does this relate to Body Mass Index (BMI)?
< 23.5cm = BMI < 20kg/m^2
> 32cm = BMI > 30kg/m^2
What part of body composition relates to disease risk?
% body fat
What are the 4 ways of measuring body composition?
- Anthropometry
- Densitometry
- Bioelectrical impedance
- Imaging techniques
What test can be used to look at muscle function? How does it work?
Hand grip dynamometer as it indicates general upper body strength
Decreased strength = increased all cause mortality
Why would you test muscle function when looking at body composition?
As muscle function responds earlier to nutritional deprivation than muscle/body mass
What does an anthropometry test involve?
Estimates volume of subcutaneous fat (adipose) via skinfolds
What are the pros and cons of anthropometry testing?
Pros: sensitive to ethnic + age variations in fat distribution, serial measurements most sensitive with comparison tables available
Cons: assumes constant ratio of subcutaneous + total fat
What is the aim of measuring the waist circumference?
To assess body fat distribution i.e. andoid (apple) vs gynoid (pear)
What must you bare in mind when measuring the waist circumference?
Men in different ethnic groups have differing waist circumference risk factors
At risk waist measurements:
- Sub Saharan African, Eastern Mediterranean + Middle Eastern = >94cm/37inch
- South Asian, Japanese + Chinese = >90cm/35inch
- ALL WOMEN = >80cm/31.5inch
What is densitometry testing?
Under water/hydrostatic weighing measuring % body fat
What are the problems with densitometry testing?
Hard to use in young, old + sick
Need to breath out as much as possible underwater
Multiple measures best
Sensitive to variations in bone mass + changes in water temp
What has superseded densitometry testing? Describe this test.
Air displacement methods - BODPOD - calculates volume of air displaced + calculates body composition from this -> results provided % body fat, lean body mass + estimate of energy expenditures
What are the pros and cons of air displacement plethysmography?
Pros: accurate
Cons: extensive hair has to be removed, expensive equipment + not portable
What is the bioelectrical impedance test?
Non invasive bedside measure which works on premise that fat does not contain water + that electrical current flows through tissues containing water + ions but not fat
What are the limitations of bioelectrical impedance?
- Error on data entry
- Requires standardised conditions
- Assumes hydration of FFM constant
- Affected by skin temperature
- Cannot use in dehydration, ascites or extremes of BMI range
What factors determine what measurement of body composition will be used?
Population group assessing
Facilities funding
Time available
What is malnutrition?
A state of nutrition in which a deficiency or excess (or imbalance) of energy, protein + other nutrients causes measurable adverse effects on tissue/body form (body shape, size + composition) + function, + clinical outcome - refers to both over + under nutrition (more commonly used to refer to undernutrition)
Give some examples of chronic, comorbid conditions that overnutrition is associated with.
Sleep apnoea Pulmonary disease NAFLD GI disease T2DM Coronary disease e.g. HPN Stroke Depression
How much does overnutrition shorten a person’s lifespan?
8-10 years
Risk for certain types of cancer increases with ___
BMI
If an obese individual loses 5-10% of their weight (20% in severe obesity), what effects will ensue?
- Reduction in risk of T2DM
- Reduction in CVD risk factors
- Improvement in blood lipid profile
- Improvement in BP
- Improvement in severity of obstructive sleep apnoea
- Improvement in health-related QoL
At what age does malnutrition become more common?
> 65 years
What is the Malnutrition Universal Screening Tool (MUST)?
All hospitals should have nutrition screening + all patients should be screened within 24hrs - developed by BAPEN
Define the term cachexia.
A condition of abnormally low weight, weakness + generally bodily decline associated with chronic disease
Wasting syndrome characterised by unintentional weight loss
What are the symptoms of cachexia?
Weight loss Muscle atrophy Fatigue Weakness Loss of appetite
How does cachexia occur?
Associated with a disproportionate loss of skeletal muscle rather than body fat
Metabolic stress e.g. injury or illness may inhibit body from using fat stores to provide energy in certain conditions which is why it is associated with cancer + other chronic disease
Why is cachexia such a big problem?
Impairs QoL + response to therapy which increases morbidity + mortality of cancer patients
What can cancer cachexia affect?
Brain (anorexia) Brown adipose tissue (thermogenesis) White adipose tissue (wasting) Heart (cardiac dysfunction) Gut (malabsorption) Liver (acute-phase response)
What complications relate to loss of lean body mass occur?
10% loss = impaired immunity, increased infection + 10% mortality
20% loss = decreased healing, weakness, infection + 30% mortality
30% loss = too weak to sit, pressure sores, pneumonia, no healing + 50% mortality
40% loss = death, usually from pneumonia + 100% mortality
What are some consequences of malnutrition?
Decreased QoL Increased risk of illness/infection Increased pressures sores/impaired wound healing Medicine less effective Longer healing times Longer hospital stays Confusion/depression/mood disturbance Increased falls (elderly) Decreased respiratory muscle strength Increased mortality
What is the cycle of malnutrition?
- Decreased energy + nutrition intake
- Muscle catabolism + weight loss
- Delayed recovery
- 2ndary infections
- Depression + lethargy
- Further decreased intake
- Serious complications e.g. pneumonia
Cycle starts again until morbidity/mortality occurs (CYCLE CAN BE BROKEN!)
What factors affect body composition?
- Biological: age (sarcopenia), gender, genetics, ethnicity, menopausal state
- Lifestyle: diet, physical activity smoking, alcohol
- Health-related factors: presence of disease, genetic predisposition
- Biometric: height, fat + muscle distribution
- Environment
