Obesity & malnutrition

Question 1

Define obesity.

Answer 1

Chronic condition characterised by excess body fat, defined by a BMI >30.

Question 2

Name some chronic diseases for which obesity is a risk factor.

Answer 2

1. Cancer
2. Type 2 diabetes
3. Hypertension
4. Cardiovascular disease
5. Osteoarthritis
6. Gall bladder disease

Question 3

Explain 2 methods for estimating desirable body weight. Which is the better measure?

Answer 3

1. Body Mass Index (BMI).
   
   • BMI (kg/m2) = weight / height2
   • may falsely classify very muscular individuals as obese
2. Waist to hip ratio
   
   • waist circumference / hip circumference
   • better measure of obesity and CVD risk

Question 4

What are the range values on the BMI scale?

Answer 4

Underweight = <18.5
Desirable range = 18.5 - 24.9
Overweight = 25 - 29.9
Obese = 30 - 34.9
Severely obese = >35

Question 5

How is abdominal obesity defined using waist:hip ratio?

Answer 5

Males: >0.9
Females: >0.85

Question 6

What % of body weight as fat is desirable/acceptable in men and women at 25 and 65?

Answer 6

Men age 25 = 15%
Men age 65 = <25%
Women age 25 = 25%
Women age 65 = <35%

Question 7

How can body fat distribution affect health?

Answer 7

Obese people having greater proportion of body fat within upper body, esp in abdomen, compared with on the hips have increased risk of:

• insulin resistance
• hyperinsulinism
• type 2 diabetes
• hypertension
• hyperlipidaemia
• stroke
• premature death

Question 8

Why is the rate of weight loss greater at the start of starvation than later on?

Answer 8

Because initially water is also lost: starvation is associated with a reduction in liver glycogen stores that are required to provide glucose for the brain; glycogen stores contain more water than fat.
As glycogen stores are used up, the rapid phase of weight loss slows toward the theoretical maximum as fat is mobilised.

Question 9

Why is total starvation not a preferred method of weight loss?

Answer 9

1. Protein metabolism increases to maintain blood glucose by gluconeogenesis (conversion of amino acids into glucose)… so after a relatively short period of time, lean body mass begins to disappear.
2. Liver begins to convert fatty acids to ketone bodies that can be used as a fuel by the CNS… but can disturb blood pH and lead to dehydration.

Question 10

To whom can The Eatwell Plate not be applied?

Answer 10

Children <2 yo
Some people with special dietary needs
Malnourished people (as have specific dietary needs)

Question 11

What is malnutrition?

Answer 11

Imbalance between what an individual eats and what that individual requires to maintain health. Can result from:

• under-nutrition (eating too little)
• over-nutrition (eating too much)
• incorrect balance of nutrients

Question 12

What are malabsorption conditions? Name some examples.

Answer 12

Failure to digest and/or absorb ingested nutrients (e.g. Coeliac disease and Crohn’s disease)

Question 13

What is protein-energy malnutrition? Give examples.

Answer 13

Spectrum of clinical conditions seen in starving adults and children, e.g. Marasmus; Kwashiorkor

Question 14

What are the symptoms of protein-energy malnutrition in adults?

Answer 14

1. Weight loss due to loss of subcutaneous fat and muscle wasting
2. Cold
3. Weakness
4. Lung and GI tract infections are common

Question 15

What is the difference between marasmus and kwashiorkor? Describe the symptoms of these.

Answer 15

1. Marasmus = deficiency in calorie intake (type of protein-energy malnutrition most commonly seen in children <5 yo)
   - emaciation with obvious signs of muscle wasting and loss of body fat
   - stomach shrinkage
   - dehydration
   - thin, dry hair
   - diarrhoea (common)
   - anaemia (may be present)
2. Kwashiorkor = severe protein deficiency
   - inability to grow or gain weight
   - distended abdomen due to ascities and hepatomegaly
   - generalised oedema
   - anaemia (common)
   - low serum albumin
   - apathy, lethargy and anorexia (loss of appetite)

Question 16

Why is oedema a symptom of kwashiorkor?

Answer 16

Insufficient amino acids for liver to synthesise normal levels of blood proteins (esp albumin)… so decreased blood oncotic pressure… so increased net flow of fluid from capillary to interstitium (Starling’s Law)… oedema.

Question 17

Which group is particularly at risk of kwashiorkor?

Answer 17

Young children displaced from breastfeeding by a new baby and fed a diet with some carbohydrate, but a very low protein content, such as cassava.

Question 18

Why is severe protein deficiency associated with increased susceptibility to infection an anaemia?

Answer 18

reduced synthesis of immunoglobulins and haemoglobin

Question 19

Why does severe protein deficiency cause fatty infiltration of the liver and hepatomegaly? What is the consequence of this?

Answer 19

1. Protein deficiency causes inability to synthesise proteins required for production of lipoproteins that normally act in the transport of fats from the liver.
2. Protein deficiency causes inability to synthesise catabolic liver enzymes.

Causes reduced liver function (e.g. low serum [albumin]).

Question 20

Why is the feeding of protein-rich food detrmimental to kwashiorkor patients?

Answer 20

Protein catabolism involves the conversion of ammonia to urea via the urea cycle in the liver. As kwashiorkor is associated with poor liver function, a high protein diet causes ammonia build up and ammonia toxicity.

Question 21

How should kwashiorkor patients be treated?

Answer 21

Start by giving a carbohydrate and fat only diet. Can wean the affected with milk products and gradually increase protein intake to daily recommended amounts.