Topic 4: Nutrition, Diet & Body weight Flashcards
What are the components of daily energy expenditure?
- Basal metabolic rate
- Voluntary physical activity
- Diet-induced thermogenesis
What is the definition of basal metabolic rate?
Measure of basal energy required to maintain the functioning of the various tissues of the body at physical, digestive and emotional rest
What is a approximated value of BMR?
In individuals who are not obese: multiplying the body weight in kg by 100
What is the definition of voluntary physical activity?
Energy required by skeletal and cardiac muscle for voluntary physical activity
What is an approximated value of energy needed for voluntary physical activity?
- Sedentary: BMR + 30% of BMR
- 2h of moderate exercise a day: BMR + 60-70% of BMR
- Several hours of heavy exercise a day: BMR + 100% of BMR
What is the definition of diet-induced thermogenesis?
Energy needed to digest, absorb, distribute and store nutrients
What is an approximated value of diet-induced thermogenesis?
10% of energy content of ingested food or sum of BMR and energy required for amount of time spent in physical activity
What are the essential components of the diet?
- Macronutrients: carbohydrate, fat and protein
- Micronutrients: vitamins and minerals
- Water
- Dietary fiber
Why are carbohydrates essential?
They are major energy containing components of the diet
Why are fats essential?
- Yields more energy than carbohydrates or protein
- Required for absorption of fat-soluble vitamins (A D E and K)
- Provide essential fatty acids (linoleic and linolenic acids) which cannot be synthesised in the body
Why are proteins essential?
- Made of amino acids which are necessary for structure and function of the body
- 9 essential amino acids cannot be synthesised and must be obtained from diet
- Some are conditionally essential (arginine, tyrosine and cysteine during pregnancy or for children)
Why is water essential?
- Maintain the body’s fluid balance
Why is dietary fibre essential?
Non-digestable plant material such as cellulose is necessary for normal GI tract function
- Reduces cholesterols and rise of diabetes
Why are minerals essential?
- Electrolytes establish ion gradients across membranes and maintain water balance
- Essential for structure (bone and teeth) - Calcium
- Signalling molecule (calcium)
- Enzyme co-factors (iron, magnesium, copper)
- Essential component of haemoglobin (iron)
Why are vitamins essential?
- If inadequate intake = deficiency diseases
- D: rickets
- E: neurological abnormalities
- B12: anaemia
- C: scurvy
- Folate: Neural tube defects
- If in excess - can be toxic
What are the clinical consequences of protein and energy deficiency in humans?
- Lead to malnutrition
- Inbalance between what an individual eats and what that individual needs to maintain health
- Spectrum of clinical conditions seen in starving adults and children
- Marasmus and Kwashiorkor
What is Marasmus?
- Protein-energy malnutrition
- Commonly seen in children <5yo
- Muscle wasting and loss of body fat
- No oedema
- Thin and dry hair
- Diarrhea is common
- Anaemia may be present
What is Kwashiorkor?
- Young child displaced from breastfeeding and fed with some carbohydrate and low protein
- Lethargic and anorexic (loss of appetite)
- Pitting oedema (indentation left behind when pressure is applied)
- Abdomen is distended due to hepatimegaly (enlarged liver) or ascites (accumulation of fluid in peritoneal cavity)
- Serum albumin is low
- Anaemia is common
How to determine the body mass index of a patient?
BMI = weight (kg) / height square (m square)
How do you interpret the values of BMI?
- Underweight <18.5
- Desirable range 18.5 to 24.9
- Overweight 25 to 29.9
- Obese 30 to 34.9
- Severely obese >35
What is the definition of obesity?
- Excessive fat accumulation in adipose tissue
- BMI >30
What are the factors involved in the regulation of body weight?
- Food choices
- Eating behavior
- Lifestyle
What is sucrose?
Disaccharide of glucose and fructose
What is lactose?
Disaccharide of galactose and glucose
