Obesity Flashcards
How is BMI measured?
weight (kg)/height (m)^2
What BMI is considered underweight?
< 18.5
What BMI range is considered healthy?
18.5 - 25
What BMI range is classed as overweight?
25-30
What BMI range is classed as obese?
30-40
What BMI is classed as grossly obese
40+
What two groups of people does BMI not work well for?
Children - best to use growth centiles
Heavy muscled adults such as athletes
Name 7 health risks of being overweight or obese
1) Elevated insulin - insulin resistance
2) Elevated BP
3) Elevated fasting glucose
4) Low HDL
5) High plasma triacylglycerol
6) Elevated atherogenic LDL
7) Elevated fasting non-esterified fatty acids
By how much does the risk of type 2 diabetes increase in obese people?
20x as likely
Rougley what percentage of hypertension is liked to excess weight?
66%
How much is risk of CHD and stroke increased by in obese men and women
2x increase for obese men under 50
2.4x increase in obese women
What percentage of cancer deaths among non-smokers are related to obesity?
10%
Name the 5 factors used to diagnose metabolic syndrome
1) Abdominal obesity
2) Hypertriglyceridemia
3) Low HDL cholesterol
4) High BP
5) Fasting Hyperglycaemia
Name a lab based way of measuring energy output
Direct calorimetry - measuring heat output or oxygen consumption
What part of the brain is associated with appetite?
Hypothalamus
What hormone acts on receptors in the hypothalamus to reduce appetite and what 3 substances work on this pathway?
Melancortin-stimulating hormone (alpha MSH).
Leptin from adipose tissue
Peptide YY from GI tract.
Glucagon-like peptide 1 (GLP-1) from GI tract
What substance increases appetite in hypothalamus? And name a substance that acts on this pathway
Neuropeptide Y (NPY). Ghrelin from GI tract acts on this
What are incretins based on and what does their release cause?
Based on GLP-1 and they reduce appetite and stimulate insulin release
Name an enzyme that inactivates GLP-1
DPP-4
What is the doubly labelled water method used for?
Measuring energy output in free-living human subjects (rather than in a lab)
How does the doubly labelled water method work?
- patient drinks water with special isotopes of H and O
- subject collects a saliva/urine sample before and for 1-3 weeks after
- mass spec. used to measure disappearance of these isotopes
- equations then used to relate these values back to oxygen consumption
Name 3 uses for the doubly labelled water method
1) Can use it to check acuracy of food intake measurements
2) Can estimate E requirements in health and disease
3) Allows us to study causes of obesity
What did the doubly-labelled water method reveal about energy expenditure in obese people compared to lean people?
Obese people expend more E than lean people because there is more of them.
Found obese people under-recorded what their energy intake was.
Also found that adipose tissue has very low metabolsim
What does initial weight loss in a diet usually consist of?
Glycogen plus water with an energy density of 1kcal/g
What does it mean by proximate and evolutionary factors of obesity?
Proximate = behaviours/lifestyle Evolutionary = heritable traits (genetics)
What is the thrifty genotype hypothesis for the cause of type II diabetes?
That genes related to type II diabetes enabled people to survive in feast and famine environments but modern lifestyles have now changed. It protected body for times when food was in short supply but that doesn’t happen now.
Idea that organs are ‘thrifty’ with the amount of glucose they use so can last longer
What does the ‘thrifty phenotype’ hypothesise is the cause of type II diabetes?
That it’s less to do with genetics and more to do with environment - development and maternal environment.
