Is weight gain socially contagious?

How can your friends be fattening?

Your social scene has the potential to impact your health and weight. Just as a friend, partner or family member can support you and make weight loss more achievable, they can also sabotage your efforts. They can influence your attitude, your expectations and your kilojoule intake.

Many social gatherings revolve around food and drink, with pressure to indulge in high kilojoule treats that you otherwise wouldn’t eat. Eating with other people can also increase the length of time you spend eating and drinking, which can also up your kilojoule intake.

Your friends may also be influencing you when it comes to food choices. Recent research has discovered that overweight friends can change what you perceive as normal and acceptable when it comes to being overweight.

The research

A study published in 2007 analysed 12,067 people over 32 years to determine whether weight gain in one person was associated with weight gain in his or her friends, siblings, neighbours or partner. They found people were most likely to gain weight when a close friend gained weight, increasing their chances of weight gain by 171 percent.

This connection was most prominent if the friend was of the same gender. Interestingly, the influence of friends remained even if they lived hundreds of kilometers away. Siblings and partners still had a strong influence (40 and 37 per cent increased risk respectively), while there was no effect when a neighbor gained or lost weight.

The researchers believe that social connections are more important than local environmental factors when it comes to weight gain. This is because the weight gain of immediate neighbors did not influence others to gain weight, yet close friends who lived a long distance away still had an impact.

It seems close friends of the same gender have the greatest potential to change what you believe is normal about your weight. If your good friend is becoming heavier, then it may seem more acceptable to become a bit fatter yourself.

Minimising the negative impact others can have on your health

If controlling your weight is an important goal, be aware of the influence that friends, and to a lesser extent, partners and siblings, can have on your results. Some strategies that may be helpful include: 

• Communication – Explain to your friends and family how important weight management is to you and that you need their encouragement.
• Don’t just meet and eat – Arrange gatherings with friends that don’t necessarily revolve around food, such as bushwalks or time at the beach.
• Spend more time with healthy friends – It’s possible that these social influences on weight gain can work in reverse. Foster your relationships with people who are active and who eat well. Identify a few friends or family members who could make a good training partner and ask if they want to exercise with you.

References available on request