Week 5 obesity 1 Flashcards
What is the prevalence of obesity in the UK?
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.
What are the categories of BMI?
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
Why is it important to measure waist circumference?
An indicator of where fat is stored
BMI is not a measure of body fat it is a measure of weight status
MRI is gold standard for classifying obesity, what is TOFI?
Thin on outside, fat on inside
MRI is gold standard for classifying obesity, what is MHO?
Metabolically healthy obesity - obese phenotype but low intra-abdominal adipose tissue.
What does research suggest about subcutaneous fat?
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
What is the impact of obesity on chronic back pain?
3x risk in obese, 2x in overweight
What is the impact of obesity on osteoarthritis?
4x risk in obese, 2.5x in overweight
What is the impact of obesity on asthma?
almost 1.5x risk in both (still slightly higher in obese)
What is the impact of obesity on stroke?
almost 1.5x risk in both (still slightly higher in obese)
What is the impact of obesity on cancer?
Increase in some types of cancers, e.g. prostrate, pancreatic, kidney
What is the impact of obesity on T11D?
7x risk in obese, 2.5x in overweight
What is adipose tissue?
An endocrine organ
What is the impact of weight gain on adipose tissue?
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.
Summarise the effect that genes has on obesity
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.
What is meant by polygenic obesity?
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.
Summarise the effect of environment on obesity
Huge environmental changes in recent times
Industrialisation, mechanisation, transport, leisure, work, diet
Genetic constitution unsuited to the 21st century
What did a study by Wang et al (2017) suggest about PA and genetic susceptibility?
Suggests high levels of PA protect against genetic disposition.
Obesity is a multifaceted problem. What are some facets of this?
Activity environment Individual activity Biology Individual psychology Food consumption Societal influences Food production
Outline how medication can be used to manage obesity
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
Outline how surgery can be used to manage obesity
BMI >40 or 35 with comorbidities
All non-surgical methods must have been tried
Various techniques e.g. gastric band
There are risks
What is energy input?
PRO, FAT, CHO
100% behaviour
What is energy output?
PA (approx. 20%)
TEF (approx. 10%)
Resting metabolic rate (approx. 60-70%)
20% behaviour
What is thermic effective feeding (TEF)?
Biochemical processes that result in energy expenditure when we eat.
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?
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)
What did Donnelly et al (2009) conclude from a study assessing PA to prevent weight gain?
PA of 150-250 min/wk with an equivalent of 1200-2000 kcal/wk will prevent weight gain greater than 3% in most adults
In n analysis of 10 studies by Ross et al (2000) looking at PA vs diet, what were the key findings?
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
