38 Questions
What percentage of body fat is present in a newborn?
14%
What is the primary method used in Bioelectrical Impedance devices to determine body fat percentage?
Sending an electrical signal through the body
What is the primary purpose of skinfold measurements?
To estimate body fat percentage
What is the typical body fat percentage of a female adult?
28%
Which of the following is NOT a method of measuring body composition?
Ultracentrifugation
What is the body fat percentage of an obese male adult?
28%
What is the primary principle of air displacement plethysmography in measuring body composition?
Measuring the volume of the chamber with and without the subject to calculate body density
What is the energy density of protein in kilojoules per gram?
22.7 kj/g
What percentage of energy from food is lost as heat?
50%
What is the energy requirement of an infant in the first year, compared to an adult?
Twice the energy requirement of an adult
What is the approximate energy expenditure of an individual playing football, compared to their basal metabolic rate?
7 times the basal metabolic rate
What is the energy density of fat in kilocalories per gram?
9.2 kcal/g
What is the approximate energy requirement during lactation?
2 MJ or 500 kcal/day
What is the part of the brain that regulates energy intake?
Hypothalamus
According to the Finnish study, which of the following is a risk factor for obesity?
Little physical activity
Which of the following conditions is associated with obesity?
Hypertension
What is the relative risk of myocardial infarction associated with obesity?
1.9
Which of the following diets is primarily used to reduce the frequency of epileptic seizures in children?
Keto diet
What is the effect of starvation on metabolic rate?
It decreases by 15-30%
Why are high protein diets often easier to follow?
Because of their satiety value of protein
What is the primary concern with keto diets?
High saturated fat content
What is the outcome of intermittent fasting compared to continuous calorie restriction?
It has the same outcome as continuous calorie restriction
What is the primary function of leptin in regulating hunger and satiety?
To signal the state of the fat stores
Which of the following neurotransmitters is involved in stimulating hunger pathways?
Neuropeptide Y (NPY)
What is the primary function of insulin in regulating hunger and satiety?
To signal the fullness of carbohydrate stores
Which of the following is NOT a short-term signal involved in regulating hunger and satiety?
Leptin
What is the primary function of PYY 3-36 in regulating hunger and satiety?
To suppress appetite
Which of the following is involved in integrating hunger and satiety signals in the hypothalamus?
The arcuate nucleus
What is the primary function of AgRP in regulating hunger and satiety?
To block the action of melanocortin peptides
What determines the last spoonful of food?
Short-term signals from the GI tract
What is the basal metabolic rate of a moderately obese person in MJ/day?
7.6
Which of the following is a socio-economic factor contributing to obesity?
Lower socio-economic class in the UK
What is the primary cause of obesity in endocrinological factors?
Adrenal hyperactivity
What is the percentage decrease in energy expenditure by children compared to 25 years ago?
65%
What is the function of propionate produced by certain gut microbes?
Decreases appetite
What is the effect of having 2 copies of the FTO gene on body weight?
3 kg heavier
What is the characteristic of individuals with 'high-risk' FTO genotypes?
Preference for high-fat foods and reduced satiety responsiveness
What is the enzyme encoded by the FTO gene?
2 oxoglutarate dependent dioxygenase
Study Notes
Body Composition
- Body composition is measured using various methods, including:
- Body density
- Body water
- Total body potassium (K)
- Methyl histidine or creatinine excretion
- Skinfold measurements (biceps, triceps, supra iliac, subscapular)
- Mid-arm circumference
- Bioelectrical impedance
- Air displacement plethysmography (Bod Pod)
- Newborns have 14% body fat, while adults have around 15-28% body fat
- Obese males have around 28% body fat
Energy Derived from Food
- Energy is derived from food in the form of:
- Carbohydrates (4 kcal/g, 16.8 kJ/g)
- Fat (9.2 kcal/g, 38.6 kJ/g)
- Protein (5.4 kcal/g, 22.7 kJ/g)
- Alcohol (7 kcal/g, 29.4 kJ/g)
Energy Balance and Control of Body Weight
- Energy balance is the balance between energy intake and energy expenditure
- Energy expenditure is influenced by:
- Basal metabolic rate (BMR)
- Diet-induced thermogenesis
- Physical activity
- Environmental temperature
- Growth, pregnancy, and lactation
- Age
- Energy requirements depend on various factors, including BMR, diet, physical activity, and environmental temperature
- Components of energy expenditure include:
- BMR
- Thermogenesis
- Physical activity
- Energy expenditure for growth, pregnancy, and lactation
Regulation of Energy Intake
- The hypothalamus plays a crucial role in regulating energy intake through:
- Hunger centre
- Satiety centre
- Satiety signals (long-term and short-term)
- Long-term satiety signals include:
- Leptin and insulin
- Neuropeptide Y (NPY) and ghrelin (hunger signals)
- Pro-opiomelanocortin (POMC) related peptides (PYY3-36) and melanocortin peptides (inhibit hunger)
- Short-term satiety signals come from:
- The GI tract
- The hepatic portal vein
- The liver
Causes of Obesity
- Causes of obesity include:
- Socio-economic and cultural factors
- Endocrinological factors (rarely)
- Physical activity
- Microbiota (gut microbes)
- Genetic factors (e.g., FTO gene)
Consequences of Obesity
- Obesity is associated with various conditions, including:
- Cardiovascular disease
- Diabetes mellitus type 2
- Hypertension
- Respiratory problems
- Gall bladder stones
- Osteoarthritis
- Reduced fertility in men
- Polycystic ovary syndrome
- Breast, endometrial, colon, and prostate cancers
Therapy: Diets
- All diets work if energy intake is restricted, but most dieters regain weight
- High protein diets can be easier to follow due to satiety value of protein
- Keto diets are primarily used for reducing frequency of epileptic seizures in children, but may be used for weight loss
- Intermittent fasting has been shown to have no benefit compared to continuous restriction of calories
This quiz covers the concept of body weight and energy balance, including body fat percentage in different age groups and genders. It's a part of the Nutrition and Metabolism module in MBBS stage 1.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
