Friends may have our backs, but their health and fitness habits can literally shape our backsides.

Multiple studies confirm that enthusiastic friends are essential to developing and sustaining healthier fitness habits. Dieters can lose more weight if partnered with supportive friends, and exercisers get more motivated if paired with positive pals (Bell & Pliner 2003; Hogan, Linden & Najarian 2002; Marcoux, Trenkner & Rosenstock 1990; Verheijden et al. 2005; Wing & Jeffery 1999). But some relationships can have the opposite effect. Either way, it turns out that the company we keep has a profound impact on body size and exercise practices (Burke & Heiland 2007; Gruber 2008; Oygard & Klepp 1996).

Close companions play a powerful role in molding fitness habits through social modeling—our tendency to mimic the actions of those around us. Nutrition and fitness professionals can stimulate the spread of healthy practices by incorporating these social realities into their wellness programs.

The Power of Friendship

Every day, someone strikes up a conversation with a stranger and discovers mutual interests. Flames of friendship ignite and a new alliance forms. Friendships are a valued source of motivation, encouragement and inspiration. Good or bad, friends shape thoughts, emotions, habits—and our physical bodies.

Social support is linked to myriad health benefits ranging from improved mental health to a more robust immune system (Bloom 1990; Jemmott & Locke 1984). The strength of these benefits is tied to the size of the social network, the emotional aspects it provides and the act of lending mutual support. Natural support networks, which include family and friends, have the greatest influence on health because they endure the test of time. Formal support networks that include wellness professionals are less influential but can foster favorable health outcomes (Hogan, Linden & Najarian 2002).

The global Edelman Health Barometer survey (2011) documented the social nature of health influence:

  • Forty-three percent of those surveyed said friends/family have the most impact on personal health lifestyle.
  • Thirty-six percent reported that close social ties have the most impact on personal nutrition.
  • About two-thirds said they had tried to change a negative health behavior, but half failed to sustain the change, citing a lack of ongoing social support as one contributor.

He Who Roams With Wolves Learns to Howl

Research suggests: “He who roams with paunchy pals becomes plump.” Christakis & Fowler (2007) followed 12,067 subjects from the Framingham Heart Study over 32 years. The study results were surprising, demonstrating that a person’s chances of becoming obese increased by 57% if a friend became obese. The type of friendship was also important. Between mutual friends, the subject’s risk of obesity increased by a whopping 171% if the friend became obese.

Gender was also a factor. The probability of obesity increased by 71% if friends were the same sex. All-male friendships resulted in a 100% increase in the chance of becoming obese, while the female-female obesity risk was about 38%. Surprisingly, proximity was not a factor: it didn’t matter if the friend lived nearby or across the country. People were more likely to pack on the pounds if their close pals did too.

This landmark study highlighted social clustering of obesity but failed to identify specific social, cultural, psychological and environmental factors contributing to the spread of obesity, although “social norms” were a suspected culprit.

Social norms are unwritten rules of socially acceptable behavior that govern things like appearance or activities (Oygard & Klepp 1996). Norms regarding acceptable body size, eating habits and exercise are learned from friends and family. Could social norms explain why obesity is contagious among close pals?

Hruschka et al. (2011) interviewed 101 women and 812 of their social ties. The findings confirmed that obesity clusters in friendship groups. However, shared social norms on body size accounted for only 20% of the obesity observed. Similarly, Leahey et al. (2011) reported obesity clusters within groups of young overweight/obese (OW/OB) adults. Although social norms didn’t account for the clustering, norms did influence weight loss intentions. OW/OB adults who had more buddies trying to lose weight had stronger intentions to lose weight.

It seems, therefore, that social modeling—rather than social norms—may play a greater role in the spread of obesity among friendship groups (Herman, Roth & Polivy 2003; Hetherington et al. 2006; Hetherington 2007).

When Dietary Awareness Is Out to Lunch

The desire to mimic those in close proximity is thought to enhance bonding and act as a social super glue (Lakin 2003). When we copy each other’s eating behaviors, we form positive, subconscious bonds with our dining companions. What people do, rather than what they think, may be why obesity flourishes among friends.

The average person makes over 200 food decisions every day (Wansink 2006a). Deciding what and where to eat are just two pieces of the dining puzzle—the other is with whom. Commiserating with pals and engaging in animated conversation over a tasty meal may feel like good therapy, but it can lead to distracted dining. Focusing on the conversation rather than the food often results in overeating (Hetherington 2006; Wansink 2006b).

The number of diners influences individual eating habits, too. If two people dine together, each will eat about 35% more than if they dined alone. If more than seven friends dine together, they will consume 96% more than they would solo (de Castro 1994). Those who eat together subconsciously model each other’s eating styles. Normally light eaters consume more when munching with a group, while heavier eaters eat less when dining with companions (Bell & Pliner 2003).

Eating behaviors are dictated by a tableside “pacesetter” who unknowingly sets the standard for how much is eaten and how fast (Herman, Roth & Polivy 2003). If the pacesetter eats one cookie, dining companions will eat one cookie. But if the pacesetter eats six cookies, then the other diners will eat about the same (Wansink 2006b).

Social modeling may hold the key to spreading healthy behaviors and curbing less-healthy ones. People who decide to adopt better eating habits may unknowingly influence their friends to do the same. The same holds true for exercise behaviors.

Workplace Weight Gain

The workplace can be a minefield for people trying to shed pounds. Co-workers can unknowingly torpedo weight loss efforts. The seemingly endless office celebrations and corporate events provide a steady stream of sugary indulgence that can sabotage the most strident dieter’s efforts. Deskside chats can tempt the most health-conscious employee into mindlessly reaching into the ubiquitous desktop candy jar, spurring weight gain.

Wansink, Painter & Lee (2006) found that secretaries given chocolates in clear jars reached for a sweet treat 71% more often than those given candies in an opaque vessel. As long as the clear dish was visible, the secretary ate 77 more calories a day, which could tack on 5 extra pounds each year (Wansink 2006c). Simply hiding the jar or placing it in a less convenient location quelled temptation. Desktop jars enticed the typical secretary into eating nine chocolates a day, or an extra 225 calories; however, stashing the jar in a desk drawer lowered the daily chocolate intake to six, and moving the jar a mere 6 feet away reduced intake to just four candies per day (Painter, Wansink & Hieggelke 2002).

The candy jar is one example of a dietary grenade; another is the “office feeder,” the co-worker who regularly deposits banana bread in the break room or leaves cookies next to the coffeepot. Simply seeing, smelling or thinking of food triggers hunger (Wansink 2006c). The good news is what is true for sweets is true for healthier foods as well. Openly displaying nutritious foods can encourage healthier workplace snacking.

While coffee breaks and corporate parties can foster camaraderie, they entice mindless eating. Here are a few tips for taming workplace temptation:

  • Put a lid on goodies. Covering them with foil or a lid will curb mindless munching (Wansink 2006c).
  • View the veggies: leave these uncovered to promote healthier grazing.
  • When dining with a co-worker, split large portions.
  • Socialize and celebrate without food.
  • Limit happy-hour drinks/alcohol.
  • Avoid desktop dining.
  • Limit the “office feeder” influence.
  • Set an example: bring in healthier snacks like fresh fruit, and replace the candy with dried fruit or nuts.
  • Support co-workers who are trying to lose weight.
Social (Media) Support

About half of the Edelman (2011) survey respondents tapped online resources, including social networks, for health information. Today’s 24/7 social media provides an ideal forum for fitness seekers to garner support, motivation and inspiration. Wellness professionals can use these social media tips to help clients enlist supportive friends:

1. Have clients make a list of simple, realistic goals, like “I want to drop a few pounds this year by making healthier choices.” Then have them post on their Facebook page: “I’m trying to [LIST GOALS HERE], and I need your support.”

2. Next, have them tell their friends what specific support they need; for example, “I need you to suggest activities that don’t involve eating/to take an interest and ask me how I’m doing/to avoid chastising me if I eat a morsel of cheesecake/to help me avoid my triggers (emotional eating, buffets) and join me for exercise.”

3. Encourage clients to use Facebook and Twitter™ to talk about successes and challenges and to track progress over time.

4. Have clients enlist friends to be “on call” when temptation ensues or if motivation is needed.

Hitting the Gym With a Friend

Exercise has numerous health benefits, but motivation and adherence are big challenges. Couch potatoes are more likely to get moving and stick with activity programs if supportive friends are involved. Group cohesion, social interaction and positive reinforcement are strong motivators to starting and maintaining an exercise regimen (Courneya & McAuley 1995; Gruber 2008; Hogan, Linden & Najarian 2002; Korkiakangas et al. 2011).

Modeling of exercise behaviors among close friends has been observed (Darlow & Xu 2011). Friends influence each other’s exercise habits, but only if the perceived support is strong (Darlow & Xu 2011, Eyler et al. 1999; Trieber et al. 1991). Women who perceived themselves as receiving medium or high amounts of exercise-specific social support tallied more sport, leisure-time and total-activity minutes, but social support was not linked to regular non-exercise-specific activity (Eyler et al. 1999). Among men, participation in exercise and sports activities is associated with friend advocacy (Darlow & Xu 2011; Trieber et al. 1991). Although women receive more exercise encouragement than men, they are less likely to exercise (Darlow & Xu 2011; Gruber 2008). Regular and long-term exercise adherence would likely improve among women if their exercise programs involved specific activities and engaged social support.

As a whole, social influence is positively associated with exercise behaviors, intentions and attitudes. Gabriele et al. (2005) explored social encouragement, which focused on positive reinforcement and positive statements such as “people important to me encourage me to exercise,” as well as social constraint or negative reinforcement, reflected by statements such as “people will be disappointed in me if I quit exercising.” Social encouragement had a direct influence on exercise motivation and behavior, while social constraint influenced only exercise commitment. When motivating someone to exercise, it is best to focus on the pros of the activity and provide positive reinforcement, according to this study.


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Martina Cartwright, PhD, RD

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