It won't surprise you to learn that people have different metabolisms and body types. Some people can eat a lot and stay thin, others have to struggle to keep pounds off.

While there is no "obesity" gene, it is the time of year when epidemiologists talk about it anyway. One such gene that has been causalated to obesity is FTO and a new paper suggest a physically active lifestyle can change that genetic determinism. 

Yes, if you exercise and burn more calories, you will lose weight.

"This provides a message of hope for people with obesity predisposing genes that they can do something about it. Our body weight destiny is not only written in our genetic blueprint," says David Meyre, an associate professor of clinical epidemiology and biostatistics at McMaster University. He and colleagues looked at data from up to 17,400 people from six ethnic groups (South Asian, East Asian, European, African, Latin American, Native North American) who were recruited from 17 countries and followed for more than three years.

"To strengthen the confidence in our results, we used both basic and precise (metabolic equivalent score) measures of physical activity, and we compared the traditional body mass index to the recently developed body adiposity index," said Hudson Reddon, first author and grad student of the Scientific Reports paper. They mapped obesity levels to 14 genes that have been statistically linked to obesity and found that exercise can blunt the genetic effect of FTO, the largest common genetic link among a lot of obest people, by up to 75 percent. 

"These promising results encourage us to investigate how additional lifestyle factors, such as diet, stress and sleep patterns, may impact the genetic predisposition to obesity," said Meyre.