What's the main cause of obesity—our genes or the environment?

September 11, 2012

The ongoing obesity epidemic is creating an unprecedented challenge for healthcare systems around the world, but what determines who gets fat? Two experts debate the issue in the British Medical Journal today.

Timothy Frayling, Professor of at the University of Exeter thinks that genetic factors are the main driver for obesity in today's environment. Twin and adoption studies show consistently that variation in body mass index has a strong genetic component, with estimated effects of up to 70%, he says.

Studies also show that people carrying two copies of a gene associated with obesity (the ) are, on average, heavier than those carrying two copies of the protective version.

A recent study of over 200,000 people showed that the FTO variant had a stronger effect in sedentary people than in those who are physically active, while studies of physical activity in schoolchildren suggest that education may not be as important as we think, he adds.

"Although DNA variations explain only a small percentage of the variation in body mass index, they provide proof of principle that genetic factors influence it over environmental factors," writes Frayling.

In conclusion, he says, genetic factors influence substantially where you are on the scale in a given population at a given time, and evidence is accumulating that these may operate largely through .

He adds: "If true, plans based on changing our environment, such as banning the sale of supersized , may be more successful than plans to increase awareness through education."

But John Wilding, Professor of Medicine at the University of Liverpool believes that changes in our environment are responsible for increasing obesity.

He acknowledges the role of genetics in the regulation of body weight, but argues that the rapid increase in obesity seen over the past 30 years cannot be due to .

In contrast, the evidence that the environment has changed is overwhelming, he says.

He points to the recent fall in the cost of energy dense foods, alongside successful promotion by the food industry, and a decline in physical activity due to changes in transport, technology, and the built environment as key drivers for the .

It will be important to identify genetic causes for rare cases that may be treated, he says. However, changes to the food and physical environment are going to be essential if we are to have a meaningful impact on the obesity epidemic.

He calls for "a radical approach … backed by strong legislation influencing food production and marketing, and ensuring the built environment and transport systems are designed to encourage active living."

In summary, he says "obesity is a complex disorder with both genetic and environmental causes. The predominant driver is environmental, and changes to the environment will be essential if we are to tackle the current epidemic."

Explore further: Physical activity reduces the effect of the 'obesity gene'

Related Stories

Physical activity reduces the effect of the 'obesity gene'

November 1, 2011
The genetic predisposition to obesity due to the 'fat mass and obesity associated' (FTO) gene can be substantially reduced by living a physically active lifestyle according to new research by a large international collaboration, ...

'Obesity genes' may influence food choices, eating patterns

May 23, 2012
Blame it on your genes? Researchers from The Miriam Hospital's Weight Control and Diabetes Research Center say individuals with variations in certain "obesity genes" tend to eat more meals and snacks, consume more calories ...

Researchers discover link between obesity gene and breast cancer

May 23, 2011
New research aimed to better identify the genetic factors that lead to breast cancer has uncovered a link between the fat mass and obesity associated gene (FTO) and a higher incidence of breast cancer. According to the study ...

Recommended for you

Link between obesity and cancer is not widely recognized

November 17, 2017
A new study published in the Journal of Public Health has shown that the majority of people in the United Kingdom do not understand the connection between weight issues and cancer. Obesity is associated with thirteen types ...

Reversing negative effects of maternal obesity

November 8, 2017
A drug that increases energy metabolism may lead to a new approach to prevent obesity in children born to overweight mothers, UNSW Sydney researchers have found.

Serving water with school lunches could prevent child, adult obesity: study

November 7, 2017
Encouraging children to drink plain water with their school lunches could prevent more than half a million youths in the U.S. from becoming overweight or obese, and trim the medical costs and indirect societal costs associated ...

Why do some obese people have 'healthier' fat tissue than others?

November 1, 2017
One little understood paradox in the study of obesity is that overweight people who break down fat at a high rate are less healthy than peers who store their fat more effectively.

Engineered protein treatment found to reduce obesity in mice, rats and primates

October 19, 2017
(Medical Xpress)—A team of researchers with pharmaceutical company Amgen Inc. report that an engineered version of a protein naturally found in the body caused test mice, rats and cynomolgus monkeys to lose weight. In their ...

Nearly 4 in 10 U.S. adults now obese (Update)

October 13, 2017
(HealthDay)—Almost forty percent adults in the United States are now obese, continuing an ever-expanding epidemic of obesity that's expected to lead to sicker Americans and higher health care costs.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.