8. Obesity

Question 1

Define overweight and obesity in adults and children

Answer 1

Excess adiposity

In children:
Overweight= BMI of +25 at age 18
Obese= BMI 30+ at age 18

Question 2

Outline the components of energy balance and what factors cause excess weight gain

Answer 2

Energy balance = Energy intake and expenditure equal

Factors which lead to weight gain:

• Lowered physical activity
• Sedentary lifestyle
• Large portion size
• Variety of food options
• Lower income background

Question 3

Understand the health implications of excess weight gain

Answer 3

CV issues
Anxiety
Depression
Anorexia
Arthritis
Diabetes 
Cancer

Question 4

be able to describe modifiable behaviours in the treatment of childhood obesity

Answer 4

Leptin therapy to those with mutation in leptin gene

Question 5

What are the two main consequences of childhood obesity?

Answer 5

Endocrine: Insulin resistance/ impaired glucose tolerance: Type 2 diabetes
CVS: Hypertension, dyslipidaemia, fatty streaks, LV hypertrophy

Question 6

Genetic link to obesity

Answer 6

Evidence: familial, twin, family, functional

Monogenic forms of obesity

• Rare
• Single gene disorders

Polygenic/ common forms of obesity
-Complex interactions between genes and environment
• gene-gene
• gene-environment
[Individual variation in obese phenotype]

Question 7

Example of environment interaction in the pathogenesis of obesity

Answer 7

Pima in Arizona
• typical American lifestyle
• typical American diet

Pima in Sierra Madre Mountains of Mexico
• traditional methods of farming, cooking, fetching water
• largely unaffected by labour saving devices

Question 8

Candidate common gene variants predisposing to polygenic obesity

Answer 8

• Peroxisome proliferator-activated receptor ( PPARG) (Pro12ala)
• Uncoupling Proteins (UCPs)
• Beta adrenergic receptors (B3-Trp64Arg)
• FTO
• MC4R…
• NPY2R
• Emerging evidence for gene variants involved in reward behaviour (e.g. DRD2 Taq1A)
• Genes linked to variation in weight through taste (e.g. CD36)

Question 9

What does GWAS stand for?

Answer 9

Genome-wide association studies

Question 10

Use of GWAS

Answer 10

Identifies new obesity loci
Whole genome studies:
• systematic analysis of genome
• powered to detect small effects by testing in large populations

Question 11

Relevance of gene FTO in obesity

Answer 11

• Found on chromosome 16
• Encodes a protein with 2-oxoglutarate-dependent nucleic acid
demethylase activity
• Role in fatty acid metabolism, DNA repair, post-translational changes
• Expressed in brain, pancreatic islet, adipose tissue, adrenal glands
• Polymorphisms on FTO gene robustly linked to BMI & obesity in adults and children

FTO VARIEANTS PREDISPOSE TO OBESITY

• Increases energy intake
• Preference for fat intake

Question 12

Explain the difference between food allergy and food intolerance

Answer 12

Food allergy: An inappropriate reaction by the body’s immune system to the ingestion of a food that in the majority of individuals causes no adverse effects.

Food intolerance:
General term used to describe a range of adverse responses to food, including allergic reactions, adverse reactions resulting from enzyme deficiencies, pharmacological reactions and other non-defined responses

Question 13

List some conditions that result from food allergy

Answer 13

Anaphylactic shock

Delayed response

Question 14

Describe common examples of food intolerance

Answer 14

Peanut allergy
Coeliac disease
Lactose intolerance
Hereditary fructose intolerance
Caffeine sensitivity

Question 15

Incidence definition?

Answer 15

The number of new cases in a population over a fixed period of time

Question 16

Period prevalence definition?

Answer 16

The total number of existing cases in a population over a fixed period of time

Question 17

Point prevalence definition?

Answer 17

The total number of existing cases in a population at a specific time