A Look into Obesity
- Obesity is a condition that entails an excess of body fat.
- It has a lot of negative consequences such as blood pressure issues, heart issues, and diabetes.
- Obesity is measured through the body mass index (BMI) whose formula is weight (kilograms) divided by the square of one's height (metres).
A BMI of 30 is usually the threshold for obesity.
- Obesity is mainly due to biological and environmental factors.
- It can also be social, cultural, and economic.
Prevalence of a Health Problem
- We can measure the prevalence in a certain population by seeing the % of people that have a BMI over 30
- We can also compare prevalence rates across populations to infer causal factors.
If a wealthier nation has a much higher prevalence of BMI than a less wealthy nation, we may infer that wealth is linked to obesity.
Marques-Vidal et al. (2010)
Aim
To investigate the link between education and obesity among a Swiss population.
Method
- The researchers conducted 4 cross-sectional health surveys in 1992, 1997, 2002, and 2007.
- Participants were categorized by age, gender, BMI, and education level.
Results
- The mean BMI increased over time.
- The mean BMI was higher among lower education levels, especially among women.
Critical Thinking
- To what extent is the above study correlation rather than causation?
- Education levels may change with age groups (e.g. a highly educated 60 year old may not be the same as a highly educated 20 year old)
Social Learning Theory
- Social learning theory is the theory of observational learning.
- We learn through imitating the actions of others.
- People may be influenced by peers, parents, and the media.
- Reinforcement may also play a role.
If your parents engage in a sedentary lifestyle, you are also likely to mimic that lifestyle.
- If someone feels relief after stress eating high-calorie food, they are likely to continue eating high-calorie food.
- The relief acts as a reinforcer.
Becker et al. (2002)
Aim
To assess the impact that TV had on eating attitudes in Fijian girls
Method
- Quasi experiment that compared 2 samples of Fijian girls before/after arrival of TV, which typically aired Western media.
- They distributed surveys to students at the beginning and then another sample with a different set of schoolgirls 3 years later about attitudes in eating including disordered behaviours.
Results
- Girls with a TV in their home were 3x more likely to have an eating attitudes test (EAT) score greater than 20, which is considered a risk for eating disorders.
- 75% said they felt too big or too fat, 69% tried dieting
This may influence rates of obesity in Fiji.
Critical Thinking
- How may the media affect SLT and obesity?
- How does socioeconomic status affect access to food?
Stress and Health Problems
- Stress releases a hormone called cortisol, which increases appetite.
- If someone is chronically stressed, they may have sustained higher levels of cortisol, which may contribute to weight gain.
- Stress may also affect metabolism, so calories are not being used properly. This may lead to an increased storage of fat.
- Stress also may lead to unhealthy coping mechanisms such as over-eating, smoking, drinking, and a lack of physical activity, which all contribute to appetite and weight.
During exam season, you may notice that you are hungrier than usual. This may be due to stress releasing cortisol and increasing your appetite.
Dockray et al. (2009)
Aim
To investigate the link between cortisol and BMI.
Method
- Children and one of their parents were interviewed about symptoms of depression and cortisol levels.
- Participants' BMI was also measured.
Results
- There was a correlation between depression and BMI.
- In girls, it was mediated by cortisol activity.
- What is the link between one environmental factor and obesity?
- How is cortisol involved in the relationship between stress and obesity?
- Why is prevalence of obesity relevant to us?
