Can obesity shrink your brain?

Can obesity shrink your brain?

There have been a couple of studies which explore this topic, explains Dr Harsh Sheth


Obesity is defined by the WHO as BMI (weight to height ratio) of more than 30 kg/m2. However, does obesity result in shrinkage of the brain? There have been a couple of studies which explore this topic and have been published.

The first is a study published by Mark Hamer of Loughborough University in the Journal of Neurology. This study examined 10,000 patients from their database and carried out magnetic resonance imaging to determine brain volumes for white and grey matter in the brain and overall brain volume.

The majority of the brain’s nerve cells are in the grey matter and include regions which control muscle movements, sensory perception, self-control etc. After adjusting for various other factors that may affect brain volume, such as age, physical activity, smoking and hypertension, 1,291 people (out of 10,000) had a BMI higher than the cut-off. These people were found to have the lowest average grey matter brain volume of 786 cc, compared to 3,025 healthy weight subjects with an average grey matter volume of 798 cc, and 514 patients with a high BMI but without a high waist-to-hip ratio had an average grey matter volume of 793 cc. There was no significant change in white matter volume.

The extra fat accumulation in the body has been hypothesised to impact the brain’s function in the long term, with a higher risk of memory loss, dementia and degenerative diseases like Alzheimer’s.The exact mechanism of this association is still being speculated. Additionally, the study investigator Mark Hamer himself is unsure whether the link found between obesity and brain shrinkage are actually correlated or just an ‘association by chance’.

(The author is bariatric, endoscopic & laparoscopic surgeon, Digestive Health Institute by Dr Muffi)