The scientist who examines the genetics of over-eating

Jacek Mokrosiński studies the genetic make-up of people who are severely obese. His research into the molecular pathways of ‘extremes’ will contribute to treatments for a stigmatised condition. Committed to social equality, Mokrosiński is also involved in LGBT initiatives at Cambridge.

My research looks at the genetic causes of obesity. We can learn a lot about the genes that make some people particularly prone to obesity by studying the extremes. At one end of the spectrum are people who remain slim whatever they eat and at the other are those who gain weight no matter what they do.

Genes can determine how we look. For example, the colour of our eyes or how tall we are. They can also be responsible for what we eat and how heavy we are. I work in the Metabolic Research Laboratories where I’m one of around 25 researchers in a team led by Professor Sadaf Farooqi. She and her colleagues are pioneers in understanding the pathways that regulate appetite and eating.

I study the genetic make-up of people who are severely obese. The people I’m interested in have a BMI of 35 or even 40 — well above the healthy level — and a multitude of related problems. We receive blood samples from people all around the world. Obesity knows no boundaries.

Some people never feel satiated. Their brains don’t tell them they’ve had enough. Our brain is set to protect us from starvation and it only tells us to stop eating once it senses that we’ve had enough. It seems that for some people, this ‘brake’ mechanism doesn’t work. Their brain keeps sending the message to continue eating.

The gene that regulates appetite regulation is called MC4R. Production of this gene is found in a tiny brain structure named hypothalamus which regulates our appetite and satiety. Among the alterations found in the DNA of severely obese people, genetic variants in MC4R are most common. We’re trying to understand how these variants change the way MC4R regulates what we eat.

Our group’s ‘chicken korma’ experiment was striking. It showed that people who carry variants in MC4R gene have an increased preference for high fat food. Offered three korma dishes with varying fat content, all looking and tasting the same, they chose the one with the highest fat content.

Obesity is not just a body weight problem. Our society often sees obesity as more than a physical condition. People with excessive weight are often blamed or stigmatised. This can make them feel isolated and depressed. Sadly, many obese people never get the support they need.

I can empathise with feelings of difference. Growing up, I felt I didn’t quite fit in and that I was somehow wrong. I resolved those feelings long ago thanks to my friends and family. They let me realise that there is nothing wrong in being who I am and living life I want. I find Cambridge very welcoming and I’m happy I can now contribute to various LGBT initiatives in our city.

I came here four years ago with my partner. We immediately felt welcome and he was invited to all the social events for partners and families.

When my post was confirmed the head of the group asked me a question. She said: do you have a partner and will he or she be moving to Cambridge with you? That little phrase ‘he or she’ meant a lot. Knowing I wouldn’t need to explain myself, I wouldn’t be judged, took a lot of weight off my shoulders.

Postdocs need more security. Postdoctoral researchers often move countries to take up posts on short fixed-term contracts. It’s difficult to plan your life when you don’t know if you will still have a job in a year or two. Cambridge University is trying hard to improve the situation and a lot has changed over the few years I’ve been working here.

I’m Polish and was brought up in the city of Łódź. We had great biology teachers at school — they went beyond the curriculum and got me interested in the wider world. I studied biochemistry at the University of Łodź and went to Denmark to do a PhD in molecular pharmacology.

A turning point came when I was 18. I was lagging behind in English and my parents sent me to London for a month’s intensive language course. At school the emphasis was on grammar and I realised that communication was much more than getting your tenses perfect. I still remember the old man at a bus stop who told me I spoke beautiful English. And eating my first British fish and chips.

I loved the multicultural aspect of London. I stayed with a Polish Jewish lady whose husband was Turkish. In the streets and at the language school I saw people from all over the world. I went back to Łódź not just speaking better English but with a sense of excitement about the world beyond Poland.

In the lab half of us are from overseas. My current colleagues come from Brazil, Greece, Belgium, India, Switzerland, South Africa and Malta as well as the UK. We have fascinating conversations. Everyone has bad days and the support of your peers is vital.

The day after the Brexit referendum the lab was subdued. Some people were almost in tears and for the first time politics was the only topic of discussion. Our British colleagues were reassuring — telling us that there was no way we’d be thrown out.

That same day the vice-chancellor of Cambridge University sent out a positive message. And within a couple of weeks, the University had invited all EU nationals among its staff to a talk at which we were given information about our status. It allayed many of our anxieties.

I’m aware that Cambridge is a bit of a bubble. The city isn’t typical of the rest of the UK. I’m interested in trying to understand the sentiments behind the anti-immigration mood that led to the Brexit vote. Visiting other towns, I’ve picked up a very different attitude.

Whenever I can, I do yoga to free my mind. I was persuaded to try a class back in Poland and immediately loved it. I’d thought it would be sitting still and staring into space. But it’s really strenuous and makes you focus deeply. It’s a chance to cut off from what’s going on in your head, all your thoughts and worries, and work really hard on your body and mind.

I love exploring. I feel great out in nature but equally I love city sightseeing. I’m passionate about architecture, especially modernism and contemporary designs. I find it fascinating how much buildings can tell you about the people and their times. Every now and then, I love going back in history, tracing my family roots. I collect stories from my relatives and search family history archives.

This profile is part of our This Cambridge Life series.



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