Week 5 obesity 1

Question 1

What is the prevalence of obesity in the UK?

Answer 1

29% of adults classified as obese in 2019 (an increase from 26% in 2017)

20% of year 6 children classified as obese (prevalence over twice as high in most deprived areas).

Overweight and obesity in adults is predicted to reach 70% by 2034.

Question 2

What are the categories of BMI?

Answer 2

Underweight - <18.5 kg/m2

Healthy weight - 18.5-24.9 kg/m2

Overweight - 25-29.9 kg/m2

Obese - 30-34.9kg/m2

Very obese - >35kg/m2

Question 3

Why is it important to measure waist circumference?

Answer 3

An indicator of where fat is stored

BMI is not a measure of body fat it is a measure of weight status

Question 4

MRI is gold standard for classifying obesity, what is TOFI?

Answer 4

Thin on outside, fat on inside

Question 5

MRI is gold standard for classifying obesity, what is MHO?

Answer 5

Metabolically healthy obesity - obese phenotype but low intra-abdominal adipose tissue.

Question 6

What does research suggest about subcutaneous fat?

Answer 6

It is healthy in appropriate amounts

Mice without sc fat are insulin resistant, diabetic, hyperlipidaemic and have NAFLD.

Surgical transplantation of sc adipose tissue reverses all metabolic derangements.

Adipose tissue secretes leptin

Question 7

What is the impact of obesity on chronic back pain?

Answer 7

3x risk in obese, 2x in overweight

Question 8

What is the impact of obesity on osteoarthritis?

Answer 8

4x risk in obese, 2.5x in overweight

Question 9

What is the impact of obesity on asthma?

Answer 9

almost 1.5x risk in both (still slightly higher in obese)

Question 10

What is the impact of obesity on stroke?

Answer 10

almost 1.5x risk in both (still slightly higher in obese)

Question 11

What is the impact of obesity on cancer?

Answer 11

Increase in some types of cancers, e.g. prostrate, pancreatic, kidney

Question 12

What is the impact of obesity on T11D?

Answer 12

7x risk in obese, 2.5x in overweight

Question 13

What is adipose tissue?

Answer 13

An endocrine organ

Question 14

What is the impact of weight gain on adipose tissue?

Answer 14

Leads to adipose tissue inflammation

Once we reach adulthood, our fat cell number does not change, as we gain/lose weight the size of the fat cells increases/decreases.

Question 15

Summarise the effect that genes has on obesity

Answer 15

Genetic influence confirmed by twin and adoption studies

Monogenic obesity - patent effect of single genes - identical twins had very similar weight gain in a feeding study.

However, while genes does play a role our genome has not changed that much in the past 70 years to be causing such an obesity epidemic.

Question 16

What is meant by polygenic obesity?

Answer 16

Combination of genes

A study looked at adopted child BMI, adopted parent BMI, and biological parent BMI.

Strongest association was between child and adopted parent, so suggests genes does play a role.

Question 17

Summarise the effect of environment on obesity

Answer 17

Huge environmental changes in recent times

Industrialisation, mechanisation, transport, leisure, work, diet

Genetic constitution unsuited to the 21st century

Question 18

What did a study by Wang et al (2017) suggest about PA and genetic susceptibility?

Answer 18

Suggests high levels of PA protect against genetic disposition.

Question 19

Obesity is a multifaceted problem. What are some facets of this?

Answer 19

Activity environment
Individual activity 
Biology
Individual psychology 
Food consumption 
Societal influences 
Food production

Question 20

Outline how medication can be used to manage obesity

Answer 20

BMI >30 or 27 with comorbidities

5 approved for use in USA and 2 in Europe

Should be used in conjunction with PA and diet

Side effects and expense

Question 21

Outline how surgery can be used to manage obesity

Answer 21

BMI >40 or 35 with comorbidities

All non-surgical methods must have been tried

Various techniques e.g. gastric band

There are risks

Question 22

What is energy input?

Answer 22

PRO, FAT, CHO

100% behaviour

Question 23

What is energy output?

Answer 23

PA (approx. 20%)

TEF (approx. 10%)

Resting metabolic rate (approx. 60-70%)

20% behaviour

Question 24

What is thermic effective feeding (TEF)?

Answer 24

Biochemical processes that result in energy expenditure when we eat.

Question 25

What did a study by Church et al (2011) show about work related activity and weight gain over a period of 50 years in the US?

Answer 25

Decrease in occupational energy expenditure

Increase in sedentary occupations

Body weight gain

Energy expenditure during work reduced by 140Kcal/d (men) and 120Kcal/d (women)

Question 26

What did Donnelly et al (2009) conclude from a study assessing PA to prevent weight gain?

Answer 26

PA of 150-250 min/wk with an equivalent of 1200-2000 kcal/wk will prevent weight gain greater than 3% in most adults

Question 27

In n analysis of 10 studies by Ross et al (2000) looking at PA vs diet, what were the key findings?

Answer 27

Results showed diet to produce much more significant weight loss than exercise

However, that’s because the energy deficit was much greater in the diet studies

When energy deficit roughly the same, weight loss roughly the same