27.2 Biochem: BMI and protein-energy malnutrition

Question 1

What is the formula for body mass index?

Answer 1

Weight (kg)/(height in metres)^2

Question 2

When does protein-energy malnutrition exist?

Answer 2

When there is an inadequate intake of macronutrients

Question 3

What are the 2 categories of PEM?

Answer 3

Kwashiorkor (protein lack)

Marasmus (starvation)

Question 4

What are the desirable % body fat ranges for men and women?

Answer 4

Men: 14-20% fat
Women: 19-30% fat

Question 5

Above age 35, what are the health effects of a BMI=27

Answer 5

It adds little extra risk to health

Question 6

What happens to fat distribution to males and females at puberty?

Answer 6

Females gain fat

Males lose fat

Question 7

What is a morbidly obese BMI defined as?

What is a fatal BMI?

Answer 7

> 40 is morbidly obese

Question 8

What happens to 3 pigs from the same litter when they are fed a diet that is:

unlimited good diet

small quantities of good diet

small quantities of good diet but with unlimited sugar

Answer 8

Unlimited: large pig
Small quantity: tiny pig
Small quantity + sugar: small pig (protein sparing but sugar=empty kJ)

Question 9

How does Kwashiorkor occur?

What is the appearance?

Answer 9

Severe protein deficit (e.g. after weaning off breast milk in poorer countries)

Has oedema (due to lack of serum albumin) with some subcutaneous fat maintained

Question 10

What is Marasmus due to?What is the appearance on a child?

Answer 10

Due to severe energy and protein deficit

Skin and bones appearance, little/no subcutaneous fat, protruding stomach

Question 11

Why do many Nigerian/African countries have Kwashiorkor sufferers?

What toxic substance does this produce?

Answer 11

Aspergillus fungus on corn/peanuts

Aflatoxin

Question 12

How is Aflatoxin metabolised? How is this toxic?

Answer 12

The P450 pathway (liver) converts aflatoxin to a reactive intermediate, epoxide

Epoxide attaches to DNA leading to cell death or cancer

Question 13

What happens (biochemically) in the first three days of starvation? What about after this?

(e.g. what are we using for fuel in the absence of ingested fuel?)

Answer 13

First 3 days: muscle protein used for gluconeogenesis

After: fat breakdown established, glycerol used for gluconeogenesis

Fat used directly as a fuel and as ketones

Question 14

What is the main problem leading to lasting neurological deficits during extended starvation?

Answer 14

Depletion of thiamine

Question 15

What happens to the gut during starvation?

Answer 15

Progressive atrophy of the villi (gut is self digesting)

Question 16

What is an ideal substance for refeeding? How might we alter this before administering it?

Answer 16

Milk! May need to be treated with lactase

use small amounts

Question 17

What happens during the first four years of life in non-dairy consuming societies?

Answer 17

Lactase (chromosome 2) production drops 90%

Question 18

How does the nitrogen balance change in starvation/burns victims/post-op patients/AIDs patients?

Why?

Answer 18

Negative balance (more excreted than consumed)

Due to the amino acid/protein breakdown

Question 19

In cancer and AIDS, high levels of what causes cachexia? This is also called…

Answer 19

TNF-a (also called cachectin)

Question 20

What is the prevalence of anorexia nervosa?

How does this prevalence differ in higher socio-economic backgrounds?

Answer 20

1-2% among schoolgirls (1/10th of this for males)

High prevalence in higher social classes

Question 21

What is the correlation between saturated fat and heart disease?

What about unsaturated fat and omega 3s and heart disease?

Answer 21

No correlation

Reduced CV disease