Is obesity genetic?

Written by: Professor Barbara McGowan
Published: | Updated: 26/11/2020
Edited by: Cal Murphy

Obesity is a huge health problem affecting millions of people around the world. It can impact the body in a number of ways, and losing weight can prove a challenge. What are the causes of obesity? Is obesity genetic? Or is there more to it than that? Professor Barbara McGowan, a London-based expert in endocrinology provides an explanation:

Obesity is a complex disease which results from the interactions between environmental factors and hereditary factors. It is well established that offspring of parents who are obese are more likely to be obese compared to children of parents who are not obese.


Monogenic mutations

There are sometimes genetic mutations in patients who are obese, which are called ‘monogenic’ and are very rare, for example, deficiencies in the leptin hormone or the receptor of the leptin hormone. Leptin is one of these hormones that reflect adipose stores within the body and if there’s an abnormality in this, patients can be very morbidly obese.



These monogenic mutations are rare and the majority of the common forms of obesity are associated with variations in several genes. This is also called polymorphism. Some of these genes are expressed in the brain, emphasizing the importance of the brain in the regulation of appetite control. If you do have polymorphism or variations in some of these genes that are predisposed to obesity, what that means is that in an environment where there is plenty of food, you’re more likely to put on weight and you’re more likely to become obese.


However, this doesn't mean that you cannot lose weight or try and achieve weight loss through lifestyle changes with support from health care professionals. Consulting your GP or an endocrinologist is a good place to start to learn what you can do to combat obesity. You can find Professor McGowan’s top tips for weight management here.

By Professor Barbara McGowan
Endocrinology, diabetes & metabolism

Professor Barbara McGowan is a London-based leading expert in endocrinology. Her special interests include weight loss, bariatric medicine, polycystic ovarian syndrome, thyroid problems, infertility, adrenal disease and pituitary disorders

After graduating with a MA in Biochemistry in 1988, Professor McGowan worked in the pharmaceutical industry, and eventually went on to study medicine at the Royal Free Hospital, London, and graduated in 1998 with merits. Thanks to her research into the role of gut hormones and other neuropeptides in appetite control, she earned a PhD from Imperial College in 2007.  

Professor McGowan was appointed a clinical lecturer at Imperial College in 2007 and in 2009 as a consultant and honorary lecturer in diabetes and endocrinology at Guy’s and St Thomas’s, London. She now leads the obesity bariatric service at Guy’s and St Thomas Hospital and is a general medicine physician.

Outside of her clinic she is dedicated to research, particularly in the areas of gut hormones and remission of type 2 diabetes post-bariatric surgery. Her work has been recognised by NIHR/RCP who awarded her for her 'outstanding contribution to research' in 2016. 

She has published extensively in high-impact journals, including The Lancet and the New England Journal of Medicine. She practices at Guy's Hospital and BMI Bishops Wood while also serving as an honorary professor at King's College London. 

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