Obesity Flashcards
What is obesity?
Accumulation of fat stores to an extent that it compromises health- WHO
Give an example of an anthropometric measurement of obesity
- BMI
- Formula= weight (kg)/heingt (m^2)
- many ADULT categories:
- Underweight: BMI <18.5
- Healthy weight: BMI = 18.5 – 24.9
- Overweight: BMI = 25 – 29.9
- Obese: BMI ≥ 30
- Severe obesity: BMI ≥ 40
What are the advantages of measuring BMI?
- Quick easy and cheap method to categorise weight in relation to health risks
- No specialist training needed/ equipment
- Widely used in population based settings around the world
- Established method of reporting in scientific literature
What are the disadvantages of using BMI to measure obesity ?
- Doesn’t allow for differences in weight between muscle and fat
- Can be an issue for athletic builds and also elderly patients
- Does not take account of the location of fat
- Differences in health risks for subcutaneous and visceral fat stores
- Ethnic differences in health risks at different BMI values
What is the link between ethnicity and BMI?
At a given BMI, health risks are markedly higher in some ethnic groups than others
- Asian populations at higher risk of diabetes and cardiovascular disease at lower BMIs than existing WHO cut-offs
- Risk varies from 22 kg/m² to 25 kg/m² in different Asian populations, and 26kg/m² to 31 kg/m² for high risk
- No population specific cut-off points but recommended lower cut offs to be used (23.5 kg/m² and 27.5 kg/m²)
Alternatives to BMI measurement
waist circumference
waist to height ratio
percentage body fat (hydrostatic body fat testing, bodyStat, BodPod, Callipers)
Describe urban-rural differences in obesity trends
- Parallel rises of urbanisation and obesity led to assumptions that urbanisation was one of the most important drivers of global rise in obesity.
- However, large-scale population datasets indicate similar or faster increasing BMI in rural areas (particularly in low- and middle-income countries, and women)
- In many countries (high-income and industrialised countries) mean BMI is higher in rural areas, especially in women.
RURAL AREAS ARE BECOMING MORE OBESITY
LMICs and rural communities in relation to obesity?
Out-dated idea of rural communities ‘living off the land’ – many areas of manual work have been automated (farming, mining, forestry)
Rural communities in low- and middle-income countries have been targeted by food companies – increasing access to cheap, highly processed, energy dense foods
Rural communities in high-income countries are disadvantaged with lower income and education, limited availability and high cost of healthy foods, fewer leisure/sports facilities, poor public transport networks
Nestle employ door to door vendors in some of the poorest parts of the world, delivering Western-style processed food and sugary drinks to most isolated pockets of Latin America, Africa and Asia
What causes obesity and overweight?
Energy imbalance between calories consumed and calories expended
- an increased intake of energy-dense foods that are high in fat and sugars; and
- an increase in physical inactivity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanization.
WHO says that it is more complex
lack of supportive policies in sectors such as health, agriculture, transport, urban planning, environment, food processing, distribution, marketing, and education
What is a more balanced perspective about interconnecting roles between the environment and the individual in terms of obesity
independent contributions of a poor diet as well as physical inactivity to excess weight gain, whilst also recognising and highlighting impact of the environment and how it influences personal ‘choices’
Biology,
Food production, nutritional and food insecurity, individual activity, sedentary lives
What is the obesogenic environment?
Food environment + activity environment
Food environment
- Availability
- Cost
- Variety
- Portion sizes
- High energy density (kcal/g)
- High fat
- Low fibre (not filling)
- Food advertising
- Portion sizes
- Snacking behaviours
Activity environment
- High cost of activity
- Labour saving devices
- Sedentary travel
- Enjoyable sedentary pastimes
- High ambient temperatures
How would eating out of the home be a risk factor to obesity?
- More than a quarter of adults and one fifth of children eat food from out of home food outlets at least once a week
- Meals eaten outside of the home tend to be associated iwth higher intakes of sugar, fat and salt and portion sezes tend to be bigger
- The increasing consumption of out-of-home meals has been identified as an important factor contributing to rising levels of obesity
Takeaway meal consumption and disease risk markers in 9-10 year old children
- Nearly three quarters of children ate a takeaway meal regularly, over 1/3 ate once or more than once a week
- Boys and children from lower socioeconomic groups consume more takeaway meals
- Children who consume more takeaway meals have higher total and LDL-cholesterol, higher fat mass
- Children who consume more takeaway meals have poorer overall diet quality
Relationship between deprivation and obesity
Obesity rates are highest for children from the most deprived areas
Getting worse
Obesity revalence of the most deprived 10% is approximately 2x that of the least deprived 10%
Impact of obesity on health and healthcare resources
Public health emergency
Obesity has been shown to have substantial economic impacts in some countries, with estimates of the costs of medical care and reduced productivity ranging from 0.13% of GDP in Thailand to 9.3% in the USA
More complex conditions and surgeries surrounding obesity
How is obesity a risk factor for COVID-19
- Obesity significantly increased the risk of COVID-19 (OR 1.46)
- Overweight increased risk of COVID-19 by 44%, and obesity nearly doubled the risk (OR 1.97)
(U.K. Biobank data, n=285 817)
- A significantly higher prevalence of individuals with obesity among hospitalised patients with COVID-19
- Pooled OR 2.13, p<0.0001
- All studies reported that among those diagnosed, patients with obesity were more likely to be admitted to ICU’s
What are the possible mechanisms for the relationship between OBESITY AND COVID?
- Obesity is associated with other risk factors for COVID-19 (hypertension, dyslipidemia, T2D, chronic kidney and liver disease), so could be indirectly related
- Obesity is associated with insulin resistance and metabolic disorders; increases in adipose tissues results in altered adipokines, impairs immune response to infection
- Dietary fatty acids (Omega-6 fatty acids) negatively affects the inflammatory responses during infection
- Increased expression of ACR-2 (increased in individuals with obesity) boosts entry of the virus into the cells and causes severe disease
Relationship between CVD and obesity
Leading cause of death worldwide
Downward trend in CVD since the 1970s
In 2009 CVD cost the NHS £8.7billion and the economy £19billion
Obesity and the risk of cancer
Link between body weight and cancer is firmly established
Meta-analysis 89 prospective studies:
Overweight and obesity associated with increased risk of breast, colorectal, endometrial, kidney and ovarian cancers
Poor mental health: discrimination and social exclusion
Employment
- Employers less willing to take obese people as employees
- Obese employees earn less and are less likely to get a promotion
Educational access
- Lower college attendance
- Lower teacher ratings of ability for obese girls
- Bullying and teasing at school
Marriage and social position
- •Less likely to get married
- •Downward SES trajectory for obese women
Social stereotyping
- Unattractive
- Weak-willed
Impact on healthcare systems
- High BMI estimated to cost health services globally US$ 990 billion per year (13% healthcare expenditure)
- Highest costs in Eastern Mediterranean and America regions
- People with obesity are more likely to develop conditions such as type 2 diabetes, heart disease and cancer – all associated with high healthcare costs
- Often require more complicated or costly care
- E.g. increasing length of stay for hip replacement
Food policy and obesity prevention
- Early years policies – support/education for care-givers
- Structure of food system – e.g. barriers to availability/cost of nutritious foods in rural areas, and neighbourhood variations in urban areas. Lack of time, physical resources, information, skills, mobility and social support
- Changing established behaviours, preferences to encourage healthier foods – food availability and presentation at point-of-purchase shapes food choices, food policy needs to influence price, availability and presentation of healthier options.
Upstream Food policy should create positive responses from food industry (mandatory labelling of trans-fats in US =removal of trans fats from products
UK Government’s ‘Tackling Obesity’ Strategy
- Improving access to weight loss programmes through Primary Care
- Changes to the ‘Food Environment’
- Banning adverts for high fat, salt or sugar products on TV and online before 9pm.
- Calorie labelling in large restaurants, cafes and takeaways.
- Ending promotion of high fat, sugar or salt products in store and online.
- Consultation on ‘traffic lights’ nutritional information and calorie labelling on alcohol
