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Researchers at the Peninsula Medical School and Oxford University found that people with two copies of a particular variant of the FTO gene had a 70% greater risk of obesity.
Dr Susan Jebb, Head of Nutrition and Health Research, MRC Human Nutrition Research, Cambridge, said:
“We have known for some time that there is a genetic susceptibility to obesity and some people are at greater risk of gaining weight than others. This research provides clear evidence of a biological mechanism which makes some people more susceptible to gaining weight in a world where food is plentiful and sedentary lifestyles the norm. By studying the action of this gene we may learn more about the detailed causes of obesity.
“People carrying a single copy of this gene are on average likely to be a kilogram heavier than people who do not carry the gene and people with 2 copies are on average almost 3 kg heavier. This is not a big difference, but, importantly, people who know they are carriers may be more motivated to adopt a prudent diet and healthy lifestyle to decrease their risk. Obesity is a complex disorder and there is no evidence from this research to suggest that carriers of the gene will not successfully lose weight by decreasing their energy intake and becoming more active.”
Douglas Smallwood, Chief Executive of Diabetes UK, said:
“Diabetes UK welcomes these important findings. The discovery of a gene linked to obesity could open the door for new research in to Type 2 diabetes.
“Although Type 2 diabetes can be genetic, being overweight is a leading factor in the development of the condition. If we can tackle obesity then we can make real in-roads in to fighting Type 2 diabetes and reducing the number of people living with the condition.
“Even though obesity may be genetic, it is vital that people who are overweight eat a well balanced diet and take regular physical activity to reduce their chances of developing Type 2 diabetes. It is important to note that obesity can not be attributed to genes in every case.
“Diabetes UK funded the original collection of samples at the beginning of this study. It is thanks to the collaborative efforts of Diabetes UK, a number of excellent international researchers and the Wellcome Trust that this discovery has been possible.”
Steve O’Rahilly, Professor of Clinical Biochemistry and Medicine, University of Cambridge, said:
“We have known for many decades that obesity is strongly inherited and, in the last 10 years, many genetic causes of severe human obesity have been discovered. This new finding represents the first clear example of a very common genetic variant that influences how fat or thin people in the general population tend to be. It is unlikely to be the only such genetic variant, but it is the first to be discovered. Unfortunately we have no idea what this gene actually does to alter our degree of fatness. It is made in every cell in the body and doesn’t look like any genes whose functions we understand so we have very few clues as to how it might affect a person’s risk of obesity. This is a very exciting first step but there is much work still to do.”
Professor Graham Hitman, one of the team of investigators, from Queen Mary’s School of Medicine and Dentistry, said:
“We currently live in a blame culture which when people gain weight it is entirely their fault. This exciting research, led by Exeter and Oxford, is the culmination of 15 years work and points to variation in a gene that if you have one copy present, in almost 50% of the general population, it will lead to a gain in weight of 1.2kilos or put 1cm on your waist; if you have 2 copies present, in 16% of the population, then you will gain almost 3kilos, than if you do not have this variation. This therefore confirms that whilst improving lifestyle is still the key to reducing the obesity epidemic, some people will find it harder to change their weight than others because of their genes. In future when we know more about the function of this gene (FTO) we may also be able to help people to lose weight more effectively despite their genes.”
Dr Sadaf Farooqi, Department of Clinical Biochemistry, University of Cambridge, said:
“While we know that nutrition and activity contribute significantly to weight gain, our genes also play an important role in determining why some people gain weight more easily than others. This study is important because it has yielded evidence for the first obesity susceptibility gene.
“At the moment no one knows how this gene works or why having a particular variant in this gene increases your risk of being overweight. More studies are needed to examine both the function of this gene and also the function of other genes that may be inherited at the same time. Nonetheless, this is an important first step in finding the genes that influence weight gain in some people. Understanding the genetic susceptibility to weight gain will make an important contribution to the prevention and treatment of obesity.”