FitnessGenes publish new research insights on obesity gene

Thursday, February 01, 2018. Author Dr. Haran Sivapalan

FitnessGenes publish new research insights on obesity gene

FitnessGenes paper sheds new light on the link between genes, lifestyle and weight gain

FitnessGenes are proud to announce the publication of new research in the peer-reviewed Journal of Obesity. The study, conducted in conjunction with Loughborough University, examined the relationship between physical activity, eating behaviors and weight gain in people with different variants of the FTO gene – also known as the ‘fat gene.’

You can read the full paper here.

The full citation for the paper is: 

West et al (2018). Effect of obesity-linked FTO rs9939609 variant on physical activity and dietary patterns in physically active men and women. Journal of Obesity.

If you don’t fancy reading an academic paper, below is a summary of the key points.

What did the study set out to investigate?

If you’ve had your DNA analyzed by FitnessGenes, you’ll know that one of the genes we test for is the FTO (fat mass and obesity-associated) gene. Colloquially dubbed the ‘fat gene’, one version of the FTO gene, the ‘A’ allele, has repeatedly been shown to increase the risk of overweight and obesity. Studies suggest that people who carry two copies of the risk A allele (the AA genotype) are 70% more likely to become obese and weigh on average 3kg more than non-carriers (who have the TT genotype).

Of course, as I’ve previously written, this doesn’t necessarily mean you’ll end up obese if you carry the risk FTO allele. How you exercise and how you eat (in short, your lifestyle) plays an important intermediary role between your genetic make-up and your ultimate bodyweight.  Aiming to further explore this interaction between genetics and lifestyle, our researchers studied the link between the FTO gene and bodyweight in a group of highly physically active people. Does physical activity attenuate a genetic predisposition towards weight gain? 

The researchers also wanted to address another question – how exactly does the FTO risk allele increase the risk of weight gain? Rather than involving changes in metabolic rate and energy expenditure, mounting evidence suggests that the FTO gene exerts its effects on the brain and eating behavior.  Neuroimaging studies show that, in risk-allele carriers, the brain’s reward circuitry reacts differently to high-calorie food and is more responsive to ghrelin: a hormone that signals hunger and tells you to eat more. And eating more is exactly what several FTO risk-allele carriers may do.

Given these effects, our research team also wanted to investigate eating behaviours, specifically participants’ feelings of hunger, uncontrolled eating and cognitive restraint – the ability to consciously restrict eating. Cognitive restraint is a particularly interesting behaviour, as consciously restricting your food intake inappropriately may, perhaps counterintuitively, actually increase your chances of overeating. This is because people with high levels of cognitive restraint may ignore internal bodily signals on when and how much to eat.  

How was the study conducted?

The study was conducted with the much-appreciated help of you guys: FitnessGenes customers! After giving their full informed consent, 528 volunteers provided a saliva sample and their DNA was analyzed in our lab. Given that we inherit pairs of genes, in this case either an A or T allele from either parent, customers’ FTO genotype was classified as either AA, AT or TT.

Customers were also surveyed about various body measurements, including height, weight, BMI and waist-circumference: so called ‘anthropometric data’. Levels of physical activity were assessed with a widely used research questionnaire, the International Physical Activity Questionnaire (IPAQ).   

Eating behaviors were analyzed using another formal questionnaire, the Three-Factor Eating Questionnaire. This research tool asks participants 51 questions about hunger (e.g. “How often do you feel hungry?”), disinhibited eating (“How often do you go on eating binges even though you are not hungry?”) and restraint (“How likely are you to consciously eat less than you want?”).

Finally, all the questionnaire data was compiled and analyzed against customers’ genotypes.

What did the results show?

We found that, in the group of highly physically active customers studied, carrying the risk ‘A’ allele of the FTO gene had no effect on BMI, waist-circumference or other markers of obesity. People with the AA and AT genotypes were not significantly heavier than those with the TT genotype. This suggests that, when it comes to weight gain, high levels of physical activity can dampen the effects of your FTO genes. This is welcome news for those of us with the AA genotype!

Interestingly, the study also found that individuals with the risk ‘A’ allele actually exercised more than those with the lower obesity-risk TT genotype. Alas, it’s not known whether this was simply an incidental quirk of the group tested or whether exercising more is somehow related to the FTO gene – more research is needed.

With regards to eating behaviour, the study revealed that individuals carrying the risk ‘A’ allele demonstrated higher levels of cognitive restraint. This is in keeping with lots of other studies of the FTO gene that link elevated obesity risk to cognitive restraint. Remember, however, that in this study we found the risk ‘A’ allele to have no impact on bodyweight. How can we reconcile these findings? Although higher cognitive restraint tends to be associated with overweight and obesity, it’s possible that consciously restricting dietary intake may counteract a genetic predisposition toward weight-gain. Again, more research is needed to fully explore this possibility.

How is the study useful?

The study helps to elucidate the complex relationship between genes, lifestyle and bodyweight. Clearly, how much you weigh isn’t a simple product of your FTO genotype. Levels of physical activity and your behaviors surrounding food both play an important role.

In addition to contributing to the academic literature, the study also generates more raw data, allowing us to further hone our nutrition and workout recommendations.

Building upon these results, we are planning further larger-scale studies for the future. The culmination of all of this is to develop increasingly accurate, predictive fitness products that ultimately benefit you, the customer.

Take home points

  • In people who are highly physically active, FTO genotype has no impact on bodyweight
  • High levels of physical activity can counteract and overcome a genetic predisposition towards weight gain.
  • The FTO gene may affect cognitive restraint - your tendency to consciously restrict how much food you eat.
  • Both your genetic makeup and your lifestyle are important when it comes to maintaining a healthy weight

We'd like to express our immense gratitude to all those FitnessGenes customers involved in our research. Your contribution to the field of health and fitness genomics is invaluable. Heartfelt congratulations are also due to Dr. Nathan West, Nicola Hansen, Dr. Samantha Decombel and Dr. Stuart Grice of the FitnessGenes team. 

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