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Healthy Psychology: Biological Causes of Obesity

Hello, everyone. I hope that you had a great Christmas Day and are now enjoying Boxing Day (A UK holiday).

Today's post is on Health Psychology and the biological causes of obesity.

This is an extract from my Health Psychology book, I hope you enjoy.

Chapter 3: biological explanations of obesity

Moving onto our first cause of obesity, we’ll be looking at the hormone: leptin and the biology of addiction to explain obesity.


Leptin is a hormone that’s involved in regulating energy intake and outtake. It does this by stopping and giving you hunger.

For example, when your Leptin levels are low the hormone tells the body that little or no fat is being stored. Making you feel hungry.

However, when you overeat your leptin levels are boosted so you don’t feel hungry anymore.

Although, some research suggests that it’s actually how the brain responds to their Leptin signals rather than the levels themselves.

As research found that only a minority of obese people had low levels; that should encourage overeat; instead research found that many obese people have increased levels of Leptin.

Therefore, suggesting that it’s not the production or amount of Leptin in the body that’s the problem but how the brain responds to these level that causes obese.

Biology of addiction:

Personally, this is an interesting one because before I read this one section of health psychology about two years ago. I never really thought of fats as drugs, but you should be able to see the link after this section.

Addiction leading to obesity is done in the following way:

· When you eat fats and sugary foods your brain secretes dopamine as a reward for you. This makes you feel amazing.

· Then you continue to eat this type of food so you can continue to get this rush. Similar to drugs.

· Then over time your brain and body builds up a tolerance to these foods and stops producing dopamine.

· Therefore, you eat more and more of these foods to get the same rush.

· In the end, as a result of you having to eat so much in order to get this rush. You built up fat quickly as you’re eating possibly thousands of more calories than you’re burning off. Leading to obesity.

Genetic factors:

Haworth et al (2008)

· Using over 2000 twins aged 7 and over 3500 aged 10, the researchers conducted a twin study to test the inheritability of BMI and obesity.

· The parents of the twins filled in a questionnaire with their children’s measures and weight so their BMI could be calculated.

· Based on their BMI the children were categorized into normal weight, overweight and obese.

· Then the BMIs were correlated between identical and fraternal twins.

· Results showed that for both types of twins’ genes played a major role in the development of obesity. Their role was about 60%-74%.

· In conclusion, BMI and obesity are largely determined by genetics. That’s the study in its simplest form.

Critical thinking:

This study has high construct validity as the method used to measure BMI and obesity is very effective. As questionnaires were a quick and simple way to get the information on the children and other factors. Instead of an interview as this can be very time consuming and expensive. Therefore, this effective method allows the researchers to measure what they want so they can draw reliable conclusions from their data.

However, as this is a twin study, it is open to population fallacy; where your sample group doesn’t actually represent your target population.; because most of the population aren’t twins. Thus, it could turn out in reality that the percentage of inheritance is much higher or lower in non-twins.


The hormone Leptin is involved in the energy consumption of people.

Fat and sugary food can lead to addiction as when you eat it the neurotransmitter dopamine gets released.

Haworth et al (2008) demonstrated that obesity can be inherited.

Thank you for reading.

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In addition, if you want to want to know more about Health Psychology then please check out Health Psychology by Connor Whiteley. Available in Ebook, Paperback, Large Print and Audiobook. (Available on Audible, GooglePlay and many more)

Have a great week.

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