Obesity

Obesity

The accumulation of excess body fat to the extent that it adversely affects health.

How is obesity commonly measured?

Using Body Mass Index (BMI); obesity is classified as a BMI of 30 or above

Why is BMI a limited measure?

It does not accurately reflect body fat mass in athletes or non-white populations

What factors influence the likelihood of becoming obese?

Socioeconomic factors such as income, education, and environment.

What is the relationship between obesity and depression?

Obesity increases the likelihood of lifetime depression, and depression is also a risk factor for obesity (Simon et al., 2006).

How does childhood depression relate to adult obesity?

Childhood depression is associated with higher adult weight (Pine et al., 2001)

What did Vittengl (2018) find about depression and obesity?

Physical impairment and emotional eating mediate the development of obesity from depression

How does weight loss surgery affect mental health?

Mental health improves after obesity surgery and weight loss in individuals with mild obesity.

How does stigma influence exercise behaviour?

Experiences of stigma increase avoidance of exercise (Vartanian & Shaprow, 2008)

What did Major et al. (2014) find about stigma and eating?

Individuals with high perceived weight were more likely to overeat when exposed to stigmatizing messages.

What is “stigmatisation by proxy”?

Stigma experienced by individuals due to association with someone who is obese.

What did Blundell et al. (2012, 2020) find about hunger?

Hunger is partially driven by fat-free mass, explaining why people with large fat stores still feel hungry.

What is the role of GLP-1?

It moves glucose out of the bloodstream into the body.

What is genetic predetermination?

Traits determined entirely by genes and not alterable by the environment.

What is genetic predisposition?

A tendency influenced by gene–environment interaction

What did Wilson (1979) study?

Longitudinal data from twins in Louisville to investigate genetic influences on obesity.

What did Stunkard et al. (1986) find in US army twin studies?

A large genetic component to obesity based on comparisons of monozygotic and dizygotic twins.

What did the Danish adoption study show?

Strong correlation between adoptees’ BMI and their biological parents, but not their adoptive parents.

What are OB-OB mice?

Mice that cannot produce leptin and are therefore obese.

How do leptin levels differ in most obese individuals?

They typically have a four-fold increase in leptin, which decreases with weight loss.

What percentage of obese individuals lack leptin?

About 4%, leading to morbid obesity that responds well to leptin treatment.

What is the MC4R mutation?

the most common monogenic cause of obesity, MC4R controls appetite in the hypothalamus found in 5.8% of children with early-onset obesity (Farooqi et al., 2003)

Prader-Willi Syndrome

damage to the sperm causes deletion of genes on chromosome 15 causing severe hunger and high risk of obesity

Which hormones are normal and abnormal in PWS?

Leptin, AgRP, and NPY are normal; ghrelin levels are high.

Externality Theory (Schachter, 1968)

Eating behaviour is influenced by both internal cues (hunger) and external cues (sight, smell, time, context). Obese individuals are over-responsive to external food cues and therefore overeat.

What did Goldman et al. (1968) find about fasting on Yom Kippur?

Fasting was perceived as less unpleasant when individuals were in a synagogue, where food cues were absent.

What did Goldman et al. (1968) find about jet lag and obesity?

Obese flight crew reported fewer jet lag complaints, suggesting reduced sensitivity to internal time cues.

What did Herman & Mack (1975) conclude about external eating?

External eating is not unique to obese individuals; it is also common in people who are dieting.

What did Drewnowski et al. (1990) find about taste preferences?

Obese individuals showed a higher liking for fat and reduced liking for sweet tastes compared to non-obese individuals.

What happened to the Pima Indians after exposure to a Western diet?

A shift from a low-fat hunter-gatherer diet led to high rates of obesity and type 2 diabetes.

What did Salbe (2004) find regarding taste preference and weight gain?

A liking for sweet and fatty foods was associated with the greatest weight gain.

What is the Portion Size Effect?

Larger portion sizes lead to increased food consumption.

How do cultural practices affect portion size effects?

Cultures like Spain (sobremesa) take longer at meals, potentially reducing overeating.

How does dietary variety relate to BMI?

Greater dietary variety is positively correlated with BMI (Lyles et al., 2006).

How does eating rate differ in obese individuals?

Obese individuals tend to eat faster than non-obese individuals (Laessle et al., 2007).

What is meant by an “obesogenic environment”?

An environment that promotes obesity through sedentary lifestyles, large portions, and expensive healthy food.

What did Crespo et al. (2001) find about TV viewing?

Higher energy intake was observed in individuals who watched large amounts of TV.

What did Ghobadi et al. (2018) conclude?

Meta-analysis confirmed TV viewing as a risk factor for obesity (risk ratio ≈ 1.3).

What is Orlistat and how does it work?

A pancreatic lipase inhibitor that reduces fat absorption.

How do Liraglutide and Semaglutide work?

They are GLP-1 agonists that reduce meal-related hyperglycaemia and increase insulin release.

What surgical methods are used to treat obesity?

Jaw wiring, vertical banded gastroplasty, and Roux-en-Y bypass surgery.

What behavioural strategies are used in obesity treatment?

Reducing portion sizes, volume eating, and increasing physical activity.

What is cue-response training? (Lawrence et al., 2015)

Go/no-go training that pairs “go” with healthy foods and “no-go” with unhealthy foods.

What is mindful eating?

Eating with enhanced awareness of hunger, satiety, and portion size, often in social settings.

What is intuitive eating?

Eating based on internal body cues rather than external rules or calorie limits.

What did Arguin et al. (2017) find about satiating diets?

Participants on a control/satiating diet showed greater reductions in fat mass despite no calorie restriction.