Impact of genetics and environmental factors on people’s weight highlighted in 2025 Linacre Lecture

Up to 70 per cent of weight differences are genetic, with common variants influencing appetite and metabolism, a pioneering research scientist has explained in a historic lecture at St John’s College

The 2025 Linacre Lecture, titled The biology of eating behaviour, was presented on 11 February by Professor Sadaf Farooqi, a Wellcome Principal Research Fellow and Professor of Metabolism and Medicine at the University of Cambridge, and the audio recording has now been published online.

Delivered every year by a leading research scientist in the field of medicine, the College’s prestigious Linacre Lecture was founded in 1524 by Thomas Linacre, physician to Henry VIII and first President of the Royal College of Physicians.

Professor Farooqi, who is Honorary Consultant Physician at Addenbrooke’s Hospital, Cambridge, studies the molecular and physiological pathways involved in the regulation of human appetite and body weight and their disruption in obesity. In 2024 she received the Outstanding Clinical Investigator Award from the Endocrine Society.

In her lecture, Professor Farooqi explained worldwide prevalence of obesity has increased dramatically in the last 30 years; 25 per cent of the UK population now have obesity, and 50 per cent are considered overweight or obese. Obesity drives many diseases, such as type 2 diabetes, cancer, cardiovascular and chronic liver diseases.

“Clearly, our environment has driven this change, but it doesn’t explain why in the same environment, there’s so much variability in how much weight people gain,” said Professor Farooqi. “Some people are much more likely to develop obesity, others can eat what they like and they stay slim.

“There’s very good evidence that a strong explanation for that variability in the population comes from genetic factors… what we know is that 40 to 70 per cent of the difference in weight between two individuals is down to differences in their genes.”

Professor Farooqi, who was elected as a Fellow of the Royal Society in recognition of her exceptional contribution to science, said people with severe obesity have a strong genetic burden. “In fact, thinness is also highly heritable. It’s as heritable as severe obesity, and we now have a new programme of research where we’re studying a cohort of 3,500 thin people,” she added. “I think that can teach us something.”

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