Body composition Flashcards
What is body composition?
The relative proportions of protein, fat, water and mineral components in the body that make up the total body weight.
Made up of fat mass and fat free mass.
What is the difference between assessing body weight and body composition?
Body weight = total weight of fat free mass and fat mass combined
Body composition = assessment of the varying components of the FFM compared to the FM
What are the constraints of BMI?
Does not take body composition into account
Should be used in conjunction with other measures (e.g. waist circumference)
Different classifications for different ethnicities
What are alternative measures of height?
Ulna length
Knee height caliper
Demi span
What is an alternative measure of weight?
Middle upper arm circumference
<23.5cm indicates BMI <20kg/m2
>32cm indicates BMI >30kg/m2
What measures are used to assess body composition?
Anthropometry
Densitometry
What measures are used to assess body composition?
Anthropometry
Densitometry (measure of bone density)
Bioelectrical impedance
Imaging techniques
How is anthropometry used to assess body composition?
Skin folds used to estimate volume of subcutaneous fat
What are the limitations of using skin folds to assess body composition?
Assumes a constant ratio of subcutaneous and total fat.
Sensitive to ethnic and age variations in fat distribution.
How is densitometry used to assess body composition?
Under water weighing measures % body fat
How does bioelectrical impedance work to assess body composition?
Works on the premise that fat does not contain water so electrical current flows through the tissues containing water and ions but not fat
What are the limitations of bioelectrical impedance?
Error on data entry Requires standardised conditions Assumes hydration of FFM is constant Affected by skin temperature Can't use in dehydration, ascites or extremes of BMI
What is malnutrition?
Refers to both over and under nutrition.
Deficiency or excess of energy, protein and other nutrients causes measurable adverse effects on tissue/ body form, function and clinical outcomes.
What chronic diseases/ clinical outcomes are associated with over nutrition?
Pulmonary disease Sleep apnoea Coronary disease Type 2 diabetes GI diseases Cancer Depression Stroke Non-alcoholic fatty liver disease
What is cachexia?
Condition of abnormally low weight, weakness and general bodily decline associated with chronic disease.
Associated with loss of skeletal muscle rather than body fat.
Symptoms include: weight loss, muscle atrophy, fatigue, weakness, loss of appetite.
What factors affect body composition?
Biological (age, gender, ethnicity, genetics)
Lifestyle (diet, physical activity, smoking)
Health-related factors (disease, genetic disposition)
Biometric (height, fat and muscle distribution)
Environment
How can food be used as an energy source?
Metabolised by KREB (Citric Acid cycle) to make ATP
What does basal metabolism rate control?
Body temperature
Autonomic functions
What are the 6 essential nutrients we need to survive?
Water Calories (e.g. from carbohydrates and fat) Protein Essential fatty acids Vitamins Minerals
What are the functions of carbohydrates?
Energy source (50-75% of our energy comes from carbs) Increase blood glucose levels
What are the functions of proteins in our diet?
Growth and repair
Supply 10-20% of energy in our diet
What are the functions of fat in our diet?
Healthy skin and hair Insulating body organs from shock Maintaining body temperature Promoting healthy cell function Storage of vitamins
Where in our diet do we get Vitamin A and what is its function?
Fish oil and green veg
Eyesight, growth, infection
Where in our diet do we get B vitamins and what are the collective functions?
Peas, grains, dairy, meat, fish, egg, green veg
Metabolism, Nucleic acid synthesis
Where in our diet do we get Vitamin C and what is its function?
Peppers, spinach, citrus fruits
Cartilage and bones
Where in our diet do we get Vitamin D and what is its function?
Sunlight, eggs, butter
Calcium and phosphorus metabolism
Where in our diet do we get Vitamin E and what is its function?
Vegetable oil
An antioxidant
Where in our diet do we get Vitamin K and what is its function?
Vegetables, fruit
Clotting
Where in our diet do we get Iron and what is its function?
Red meat, fortified cereals, green leafy vegetables
Component of Hb for oxygen transport
Where in our diet do we get Calcium and what is its function?
Milk
Bones and teeth; nerve and muscle function
Where in our diet do we get Zinc and what is its function?
Meat, seafood, wholegrains
Enzymes, immune system
Where in our diet do we get Magnesium and what is its function?
Meat, dairy, green veg, nuts
Metabolism; nerve and muscle function
Where in our diet do we get Potassium and what is its function?
Fruit and veg
Fluid balance; nerve and muscle function
What are the time limits for fed, fasting and starved states?
Fed = 0-4 hours after food Fasting = 4-12 hours after food Starved = 12+ hours after food
Where does your body get energy from when in a fasting state?
Glycogen stores broken down into glucose to supply brain, nervous system and blood cells (+ other cells)
Body fat stores broken down into fatty acids to provide energy to other cells
Where does your body get energy from when in a starved state?
Body protein broken down into amino acids which are then broken down into glucose and ketone bodies:
Glucose provides energy to the brain, nervous system and blood cells (+ other cells) whilst ketone bodies provide energy to other cells of the body
Body fat stores are broken down into fatty acids which provide energy to other cells and ketone bodies which provide energy for the brain, nervous system and blood cells
