Your partner has a greater influence over your risk of becoming obese than your genetics or upbringing, which makes being healthy while in a relationship a worthwhile endeavour.

A new study, published in the journal PLoS Genetics and conducted by experts at the University of Edinburgh, suggests people with a family history of obesity can still lose weight and reduce their risk by changing their lifestyle in middle age.

The key is who you share your life with, and how.

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“Although genetics accounts for a significant proportion of the variation between people, our study has shown that the environment you share with your partner in adulthood also influences whether you become obese and this is more important than your upbringing,” the study’s lead author, Professor Chris Haley, explained in a statement.

Science is only starting to explore the impact of partner eating habits. Photo: Getty

The medical community is gradually becoming aware of the impact of partners on health, a nutrition expert told The New Daily.

“The big problem is this is an age group that we’ve never really researched. We’ve mainly concentrated on children or people who are already obese,” said University of Sydney Professor Ian Caterson, president-elect of the World Obesity Federation.

The scale of the problem

People tend to gain weight after milestone life events such as marriage, according to Professor Caterson.

“It’s probably a change in their eating pattern because they’re now cooking for two,” he said.

“Also, people who play sports or other physical activities tend to stop once they get married or start a family.

“The other relevant milestone is having children. A lot of women date their weight problems from their first or second pregnancy.”

Being overweight or obese increases a person’s risk of developing other chronic health conditions such as heart disease and Type 2 diabetes. The most recent data on obesity by the ABS shows five in every eight Australians over 18 years old are either overweight or obese.

The good news

But if the person you share your life with can have a negative impact on your waistline, they can also be a force for positive change.

Professor Mark Harris, chief investigator at UNSW’s Centre for Obesity Management, said people generally find losing weight easier if they make it a mutual goal with their other half.

Weight loss needs to be tackled together. Photo: Getty

“It’s difficult within a family to have your own unique lifestyle, so trying to build up good habits together is kind of reinforcing,” he said.

“Trying to establish healthy patterns of behavior isn’t always the easiest thing to do, but nagging people and just saying things like ‘don’t eat that’ is almost certainly counterproductive.”

University of Sydney’s Professor Caterson agreed, saying it’s easier to make decisions on what foods to buy and where to dine out and ways to keep fit with this combined approach.

“It’s a matter of saying things like, ‘Let’s make sure we don’t go overboard’. Or ‘Ok, do we continue our sporting interests individually, or is there something we can do as a couple?’. Generally, learning balance in life between eating and activity.”

How to create a healthy partnership

Nutrition Australia senior dietitian Aloysa Houriga said couples where only one member is overweight generally find it harder to work together in creating a healthier lifestyle. But this shouldn’t stop them from trying, because ultimately being healthy is hardest when attempted alone.

“If someone has support from their other half, it makes it easier because it means they have someone to do it for, other than themselves,” Ms Hourigan said.

“They could start eating more vegetables because their partner does, or ask them to start cooking more healthy foods.

“Ultimately it’s about creating an environment that makes it easy for [each other] to make healthy lifestyle choices.”

People looking for more information on how to prepare healthy food can visit 8700.com.au.