Body Weight and Energy Balance

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Questions and Answers

What percentage of body fat is present in a newborn?

19%
14% (correct)
10%
28%

What is the primary method used in Bioelectrical Impedance devices to determine body fat percentage?

Sending an electrical signal through the body (correct)
Measuring body density
Analyzing body water composition
Measuring mid-arm circumference

What is the primary purpose of skinfold measurements?

To determine total body potassium
To measure body density
To measure mid-arm circumference
To estimate body fat percentage (correct)

What is the typical body fat percentage of a female adult?

28% (C) Signup and view all the answers

Which of the following is NOT a method of measuring body composition?

Ultracentrifugation (D) Signup and view all the answers

What is the body fat percentage of an obese male adult?

28% (C) Signup and view all the answers

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 (A) Signup and view all the answers

What is the energy density of protein in kilojoules per gram?

22.7 kj/g (B) Signup and view all the answers

What percentage of energy from food is lost as heat?

50% (B) Signup and view all the answers

What is the energy requirement of an infant in the first year, compared to an adult?

Twice the energy requirement of an adult (D) Signup and view all the answers

What is the approximate energy expenditure of an individual playing football, compared to their basal metabolic rate?

7 times the basal metabolic rate (A) Signup and view all the answers

What is the energy density of fat in kilocalories per gram?

9.2 kcal/g (B) Signup and view all the answers

What is the approximate energy requirement during lactation?

2 MJ or 500 kcal/day (D) Signup and view all the answers

What is the part of the brain that regulates energy intake?

Hypothalamus (B) Signup and view all the answers

According to the Finnish study, which of the following is a risk factor for obesity?

Little physical activity (B) Signup and view all the answers

Which of the following conditions is associated with obesity?

Hypertension (A) Signup and view all the answers

What is the relative risk of myocardial infarction associated with obesity?

1.9 (C) Signup and view all the answers

Which of the following diets is primarily used to reduce the frequency of epileptic seizures in children?

Keto diet (D) Signup and view all the answers

What is the effect of starvation on metabolic rate?

It decreases by 15-30% (C) Signup and view all the answers

Why are high protein diets often easier to follow?

Because of their satiety value of protein (D) Signup and view all the answers

What is the primary concern with keto diets?

High saturated fat content (B) Signup and view all the answers

What is the outcome of intermittent fasting compared to continuous calorie restriction?

It has the same outcome as continuous calorie restriction (B) Signup and view all the answers

What is the primary function of leptin in regulating hunger and satiety?

To signal the state of the fat stores (D) Signup and view all the answers

Which of the following neurotransmitters is involved in stimulating hunger pathways?

Neuropeptide Y (NPY) (D) Signup and view all the answers

What is the primary function of insulin in regulating hunger and satiety?

To signal the fullness of carbohydrate stores (B) Signup and view all the answers

Which of the following is NOT a short-term signal involved in regulating hunger and satiety?

Leptin (D) Signup and view all the answers

What is the primary function of PYY 3-36 in regulating hunger and satiety?

To suppress appetite (D) Signup and view all the answers

Which of the following is involved in integrating hunger and satiety signals in the hypothalamus?

The arcuate nucleus (B) Signup and view all the answers

What is the primary function of AgRP in regulating hunger and satiety?

To block the action of melanocortin peptides (B) Signup and view all the answers

What determines the last spoonful of food?

Short-term signals from the GI tract (D) Signup and view all the answers

What is the basal metabolic rate of a moderately obese person in MJ/day?

7.6 (D) Signup and view all the answers

Which of the following is a socio-economic factor contributing to obesity?

Lower socio-economic class in the UK (B) Signup and view all the answers

What is the primary cause of obesity in endocrinological factors?

Adrenal hyperactivity (A) Signup and view all the answers

What is the percentage decrease in energy expenditure by children compared to 25 years ago?

65% (B) Signup and view all the answers

What is the function of propionate produced by certain gut microbes?

Decreases appetite (A) Signup and view all the answers

What is the effect of having 2 copies of the FTO gene on body weight?

3 kg heavier (D) Signup and view all the answers

What is the characteristic of individuals with 'high-risk' FTO genotypes?

Preference for high-fat foods and reduced satiety responsiveness (D) Signup and view all the answers

What is the enzyme encoded by the FTO gene?

2 oxoglutarate dependent dioxygenase (B) Signup and view all the answers

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

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Description

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.