Does obesity cause depression?

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Is there a relationship between obesity and depression? Join us as we explore and explain the latest studies.

Obesity and depression have quite a lot in common.

They can have similar causes, including genetic and social factors. They're both linked with physical health problems. And both are on the rise.

According to government data, the proportion of adults living with obesity in the UK rose from 14.9% to 28% between 1993 and 2022.¹ And a 2023 study found that the incidence of common mental disorders, including depression, stress and anxiety, had increased by 42% since 2000.

Is this all a coincidence? Or do these two conditions go hand in hand?

That's what we'll look at in this article. We'll explore the relationship between obesity and depression and ask, 'Does one cause the other?'.

Defining obesity and depression

Before we dive into the details, let's make sure we all understand the key terms.

First, obesity.

There are lots of debates around the classification of obesity. Is obesity a disease as the World Health Organisation (WHO) claims, or, as the NHS puts it, a 'serious health concern'?

It can all get quite fuzzy quite fast. But thankfully, the medical definition is widely agreed upon. A person has obesity if they have excess body fat and a BMI of 30 or greater. Your BMI is calculated using your weight and height and can indicate whether you're at a healthy weight.

Depression is a little more difficult to define. In this article, we'll use the WHO's definition. 'Depressive disorder, or depression', it says, 'is a common mental health condition […] characterised by a low mood or loss of pleasure or interest in activities for long periods of time.'

Obesity and depression can both negatively impact a person's health and quality of life. Obesity can make it harder to take part in activities and is linked to health problems like heart disease, stroke and certain types of cancer. Depression, meanwhile, is associated with social withdrawal, feelings of low self-worth and an increased risk of suicide.

What's the relationship between obesity and depression?

It's well-established that having a high BMI is linked to depression and anxiety.

However, it's not as simple as asking, 'How can obesity cause depression?' A growing body of evidence points to a more complex relationship between the two conditions. Obesity and all its associated problems likely do cause depression – but depression, in turn, increases the risk of obesity.

In other words, it's a vicious cycle – one condition feeds and reinforces the other. Or, as one paper puts it, 'The two disorders can be interrelated through a vicious, mutually reinforcing cycle of maladaptive physiological adaptions'.

A 2010 review put this relationship into sharp focus. The researchers found that people with obesity had a 55% increased risk of developing depression. However, they also discovered that having depression led to a 58% increased risk of developing obesity.

Why does one condition make the other more likely?

The relationship between obesity and depression is highly complex – and, at this point, not fully understood.

But one possible link seems fairly self-evident. There is, unfortunately, a social stigma attached to obesity. It's easy to see how childhood teasing, social snubs in adulthood and the pressure of weight-obsessed beauty standards could contribute to a person's low mood.

As for depression causing obesity – again, we could take a guess. One of the characteristic markers of depression is a lack of enthusiasm for activities. That includes the physical activities and exercise that are crucial for maintaining a healthy weight.

Moreover, many common antidepressants – including amitriptyline and citalopram – can cause weight gain as a side effect.

Antidepressants are highly effective for many people – but they may, to some degree, be contributing to the vicious cycle of depression and obesity.

And there may be more going on inside our bodies that can help us draw a link between the two conditions.

For instance, there's a growing body of evidence that suggests depression is linked to inflammation in the body.

Obesity can also cause inflammation – and researchers are studying whether this contributes to the vicious cycle.

Another interesting – and related – area of study is the link between mental health and the gut. Our intestines are full of tiny organisms that are essential for a healthy digestive system. Researchers note that improving the makeup of these organisms may have beneficial effects on depression and anxiety. However, more research is needed before these effects are fully understood.

How to get help with depression and anxiety

If you're struggling with depression or anxiety, it's important to know that help is available. You never have to suffer alone.

Here are some useful contacts for people in the UK:

The NHS website is a good place to start looking for help. It has lots of information about local mental health services, as well as how to get therapy on the NHS.
If you need to talk to someone now, you can call Samaritans on 116 123. Alternatively, you can contact the charity online or write them a letter.
If you need urgent help, call NHS 111 now or use the online service.
If you're in danger or think someone else might be in danger, call 999 straight away.

Are you outside of the UK? The website findahelpline.com lets you search for free, confidential helplines in your country. Call your local emergency number if you or someone you know is in danger.

SemaPen is a UK-based private healthcare provider. We help people living with obesity using expert-led custom weight loss plans.

Sources

1. https://commonslibrary.parliament.uk/research-briefings/sn03336/

2. Dykxhoorn, J. et al. (2023) "Temporal patterns in the recorded annual incidence of common mental disorders over two decades in the United Kingdom: a primary care cohort study" Psychological Medicine, 54(4) https://doi.org/10.1017/S0033291723002349

3. Zhao, G. et al. (2009) "Depression and anxiety among US adults: associations with body mass index" International Journal of Obesity, 33 https://doi.org/10.1038/ijo.2008.268

4. Fu, X. et al. (2023) "Shared biological mechanisms of depression and obesity: focus on adipokines and lipokines" Aging, 15(12) https://doi.org/10.18632/aging.204847

5. Luppino, F.S. et al. (2010) "Overweight, Obesity, and Depression: A Systematic Review and Meta-analysis of Longitudinal Studies" Archives of General Psychiatry, 67(3) https://doi.org/10.1001/archgenpsychiatry.2010.2

6. Berk, M. et al. (2013) "So depression is an inflammatory disease, but where does the inflammation come from?" BMC Medicine, 11 https://doi.org/10.1186/1741-7015-11-200

7. Shelton, R.C. et al (2011) "Inflammation in depression: is adiposity a cause?" Dialogues in Clinical Neuroscience, 13(1) https://doi.org/10.31887/DCNS.2011.13.1/rshelton

8. Schachter, J. et al. (2018) "Effects of obesity on depression: A role for inflammation and the gut microbiota" Brain, Behavior and Immunity, 69 https://doi.org/10.1016/j.bbi.2017.08.026

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