Exercise more beneficial for those with higher genetic risk of obesity

A study examining the interaction between individuals' genetics and 18 types of exercise has found that certain physical activities could reduce the genetic effects that cause obesity.

Researchers at Taiwan University examined 18,424 unrelated Han Chinese adults between 30 to 70 years old who participated in the Taiwan Biobank (TWB). They assessed their self-reported exercise routines against five measures of obesity: body mass index, body fat percentage, hip circumference and waist-to-hip ratio. Using lifestyle and genomic data from the TWB, they constructed genetic risk scores for each of the obesity measures and then tested whether certain exercises counteracted the risk. 

Overall, they showed that those with the highest risk of obesity benefited most from regular exercise. In addition, a regular routine of jogging was shown to be the most effective, followed by mountain climbing, power walking, walking and long yoga sessions.

'This study adds to the collection of emerging evidence of the benefits of physical exercise in reducing obesity in those of us with and without the genes that make it easier for us to gain weight,' said Professor Lora Heisler, Chair in Human Nutrition, Rowett Institute, University of Aberdeen.

Obesity is a major global public health problem, especially in developed countries. The complex interplay between multiple genes involved in obesity – up to 400 different genes – and lifestyle factors, makes it difficult to tackle this condition.

Dr Simon Cork, Lecturer in Medical Education, King's College London, noted that 'The study was performed only on people of Han Chinese ethnicity. It is not clear whether the results from this study will be applicable to say Caucasian or Afro-Caribbean individuals, who may have different genetic predispositions.'

Dr Cork also urged people to be cautious of the results, adding: 'Various studies have shown that exercise alone is not sufficient to lose significant body weight in the absence of more general lifestyle changes (such as diet). So, while this study does suggest that some types of exercise are better than others (at least in the Chinese Han population), people should be cautious about employing these techniques as their primary source of weight loss.'

It is not clear why jogging was the most favourable exercise in this population; however, running is known to provide several benefits, including improved circulation and oxygen distribution in the body, potentiated memory, cognitive function and reduced stress. Interestingly, other types of exercise, such as swimming, cycling and stretching did not modify the genetic effects on any of the obesity measure, but researchers did not take into account the intensity of exercises undertaken, which would ideally have been controlled for. 

Dr Wan-Yu Lin, Associate Professor at Taiwan University and lead author, said: 'Exercises in cold water such as swimming can especially stimulate appetite and food intake.'

Doctors often recommend exercise to people who are at risk of obesity, but the type of exercise chosen is rarely selected based on people genetic make-up. Therefore, this study warrants further investigation to understand how effective exercise can be tailored to those individuals at risk of obesity in the wider population.

Dr Jenifer Logue, Clinical Reader and Honorary Consultant in Metabolic Medicine, Lancaster University, added: 'This was observational research with self-reported activity levels; controlled clinical trials would be needed to prove these finding and change clinical guidelines.'

The study was published in PLOS Genetics.