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Back in May 2016, I published a blog and podcast with the title, Obesity & Depression: opening Pandora’s Box ( aim of the blog and podcast was to briefly discuss a possible link between these two very common chronic conditions, especially since there appears to be some evidence that the use of antidepressants could play a role in fostering weight gain. 

I received  a ‘hot off the press’ copy of the journal of the American College of Nutrition this week, and amongst the articles published in this new edition is one entitled, Overweight and Obesity Associated with Higher Depression Prevalence in Adults: A Systematic Review and Meta-Analysis. The terms ‘Systematic Review’ and ‘Meta-Analysis’ tell us that the authors of this particular study went to great lengths to see what other studies have found in investigating possible links between being overweight and depressed. This ‘chicken & egg’ post considers some of the findings of the abovementioned study.

But before we take a brief look at the new study, I’d like to remind readers ( and myself!) that both of these conditions – overweight/obesity and depression – are complex multifactorial conditions and we should, therefore, guard against taking a reductionist or simplistic approach in trying to come to grips with the obesity-depression conundrum. 

How bad are the problems?

The World Health Organization (‘WHO’) estimates that around 1.3 billion adults are overweight and about 600 million are obese. They also estimate that approximately 350 million people of all ages suffer from depression. Adding these numbers together reveals that about 2 billion people currently are at risk for the downstream consequences of these conditions.

The authors of the meta-analysis mentioned earlier found that being obese, i.e. having a body mass Index (‘BMI’)  of 30kg/m2 or more, increased the risk of being depressed by about 32% when compared to the risk experienced by normal weight people. For obese women the risk increased even more; around 36%. Even being overweight and not obese (BMI between 25 and less than 30kg/m2) increased the likelihood of being depressed, but not to the same extent as in the obese population. While there is an association between being overweight or obese and depression in both men and women, the study revealed that the problem is much greater in women.

Why should being overweight or obese increase the risk of being depressed?

Intuitively, we might think that just being overweight or obese might make us feel ‘down’ or  ‘depressed’ because of the surfacing of negative emotions linked to our ‘less than perfect’ body shape. Words and thoughts like shame, embarrassment, guilt, humiliation, fear, etc. may come to mind. While prevailing societal norms, fashion and the idealising of others, especially celebrities (see ‘Celebrity Psychosis’ no doubt contribute to how we see ourselves, it appears that biology too may play a major role in the obesity-depression continuum. 

Is biology to blame?

There are a number of biological (as opposed to psychological)  theories knocking around in the scientific community as to why carrying excess weight is associated with an increased risk of being depressed. One of these (and it’s one that I have to say makes a lot of sense to me) puts the biological blame squarely in the corner of inflammation. Now we know that not all inflammation is bad for us (see, but chronic or ongoing low-grade inflammation most certainly is.

What appears to happen to us when we put on excess weight goes something like this: excess fat, especially visceral or ‘tummy’ fat, causes us to produce proinflammatory biochemical compounds as well as being responsible for the dysregulation or imbalance of an important interacting hormone system. The mixture of scrambled hormones and inflammation-causing biochemicals leads to damage to our cells. We call this type of damage oxidative stress. When the cells of brain are the ones being damaged by oxidative stress we end up with what is known as  ‘neuronal degeneration’, which in turn increases the risk of depression. 

So what are we to do?

As I mentioned in the introduction to this blog, both overweight/obesity and depression are complex conditions. In other words, both conditions are comprised of, and effected by, a number of interacting and interdependent biological, psychological, sociological, behavioural and even spiritual factors.  It follows, therefore that if the cause and trajectory of these conditions are complex, then the solutions can’t be simple ‘one-size-fits-all’ either. Popping a pill for depression or eating less and exercising more in order to lose weight may provide some short term benefits for some of us, but neither of these simplistic solutions are likely to lead to sustainable positive outcomes in the long term.

In a previous blog (, I mentioned that the solution to dealing with chronic diseases of lifestyle does not lie in taking outside-in approaches. Maybe the answer is more likely to be found walking the inside-out path to health. Perhaps Pogo, the comic strip character from a bygone era, was onto something when he uttered the immortal words, ‘Yep son, we have met the enemy and he is us’?

What do you think?

I’m Dr Peter Hill for UpForIt.