We can unravel the role that bodyweight plays in disease, but we need a bigger, more diverse, sample of genetic material to do so
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When I was a young postdoctoral researcher at Cambridge in 2002, a colleague took me to a fancy dinner at Peterhouse College, the oldest of Cambridge’s colleges.
It was a six-course affair and, rather ridiculously, you had to change seats (and hence dinner companions) for each new course. During the first course, an older, bearded professor sitting opposite me asked, “So young man, what do you do?”
I told him I was working on the genetics of childhood obesity.
“Ha! Do you know what your problem is?” he replied. “You give fat people an excuse.”
The disgust in his tone threw me and as I mobilised all my diplomatic nous to gently push back, I was saved by a literal bell, signalling that we had to switch seats for course number two.
It occurred to me later that the professor’s view was shared by much of society. Obesity is seen as a problem of physics; people just need to eat less and move more. But although howwe get to our bodyweight is reliant on physics, the real question is why? Why do people behave so differently toward food? Why do some people respond to stress by eating more and others by eating less? Why do some people love food, while for others it’s simply fuel?
Why, what, when and how much we eat have powerful societal and cultural underpinnings. But there are equally powerful genetic factors that influence our eating, and hence our bodyweight.
Large population-based studies, such as UK Biobank, a survey of nearly half a million adults, has helped to reveal the genetic architecture underlying differences in body size. For instance, we now know of over a thousand genes that are linked to bodyweight, and the vast majority are expressed in the brain and influence our eating habits.
What’s intriguing is that, while there are overlapping genes, there are unique genetic signatures linked to developing obesity in childhood versus gaining excess fat as an adult.
But since UK Biobank is a survey of adults, the childhood obesity data was obtained by asking the participants: ‘When you were 10 years old, compared to the average, would you describe yourself as thinner, plumper, or about average?’
This relies on memory, but most people do recall their body size as children. It is, however, still a blunt measure and crucially, m
