People who make an effort to lose weight are not just helping themselves, they may be helping others too, a study suggests.
Researchers have found that when one member of a couple commits to losing weight, the chances are good their partner will lose some weight too, even if they are not actively participating in a weight loss intervention.
They tracked the weight loss progress of 130 couples over six months.
In the study, about one third of the untreated partners lost three per cent or more of their initial body weight after six months despite not participating in any active intervention.
A three per cent loss of body weight is considered a measurable health benefit.
"When one person changes their behaviour, the people around them change," said Amy Gorin, from the University of Connecticut in the US.
The study, published in the journal Obesity, also found that the rate at which couples lose weight is interlinked.
In other words, if one member lost weight at a steady pace, their partner did too. Likewise, if one person struggled to lose weight, their partner also struggled.
"How we change our eating and exercise habits can affect others in both positive and negative ways," said Gorin.
The researchers recorded objective measurements of participants weight and examined couples weight loss trajectories over time.
The couples were divided into two groups. In one group, one member of the couple was enrolled in a structured six- month weight loss program that provided in-person counselling and online tools to assist with weight loss.
In the second group, one member of the couple received a four-page handout with information on healthy eating, exercise, and weight control strategies.
Contact with those individuals stopped with the handout.
The results showed that the untreated partners of both those who tried losing weight on their own and those who participated in the structured program also exhibited weight loss at three and six months.
