Eating is fundamental aspect of human life, but what are the factors that influence our eating behavior?
Scientists have explored this question for over a century, and early studies focused solely on physiological influences on food intake. For example, in 1912 Walter Cannon and his student Washburn discovered that stomach contractions accompanied feelings of hunger. In the 21st century, many people still attribute their eating behavior primarily to factors such as hunger and taste. However, research on the psychology of eating indicates that the social presence and behavior of others can also have an enormous impact on food consumption.
How do friends, family, and peers influence our eating? Psychology of eating experts Peter Herman, Deborah Roth, and Janet Polivy (2003) have reviewed three important social effects:
1. Social facilitation – When eating in groups, people tend to eat more than they do when alone.
In daily diary studies, individuals have been found to eat from 30-50% more while in the presence of others versus eating alone. In fact, some research has indicated that the rate of intake is best described as a linear function of the number of people present, such that meals eaten with one, four, or seven other people were 33%, 69%, and 96% larger than meals eaten alone, respectively.
Meal duration may be an important factor in social facilitation effects; observational research has identified positive correlations between group size and meal duration, and further investigation has confirmed meal duration as a mediator of group size-intake relationships.
2. Modeling – When eating in the presence of others who consistently eat either a lot or a little, individuals tend to mirror this behavior by also eating either a lot or a little.
Early studies of modeling effects assessed food intake alone versus in the presence of others who either ate either a very small amount (1 cracker) or a larger amount (20-40 crackers). Findings were consistent, with individuals consuming more when paired with a high-consumption companion than a low-consumption companion, whereas eating alone was associated with an intermediate amount of intake. Research manipulating eating social norms within real-life actual friendships has also demonstrated modeling effects, as individuals ate less in the company of friends who had been instructed to restrict their intake versus those who had not been given these instructions.
Furthermore, these modeling effects have been reported across a range of diverse demographics, affecting both normal-weight (BMI 18.5- 25) and overweight (BMI 25- 30) individuals, as well as both dieters and non-dieters. Finally, regardless of whether individuals are very hungry or very full, modeling effects remain very strong, suggesting that modeling may trump signals of hunger or satiety sent from the gut.
3. Impression management – When people eat in the presence of others who they perceive to be observing or evaluating them, they tend to eat less than they would otherwise eat alone.
Leary and Kowalski (1990) define impression management in general as the process by which individuals attempt to control the impressions others form of them. Previous research has shown that certain types of eating companions make people more or less eager to convey a good impression, and individuals often attempt to achieve this goal by eating less. For example, people who are eating in the presence of unfamiliar others during a job interview or first date tend to eat less.
In a series of studies by Mori, Chaiken and Pliner (1987), individuals were given an opportunity to snack while getting acquainted with a stranger. In the first study, both males and females tended to eat less while in the presence of an opposite-sex eating companion, and for females this effect was most pronounced when the companion was most desirable. It also seems that women may consume less in order to exude a feminine identity; in a second study, women who were made to believe that a male companion viewed them as masculine ate less than women who believed they were perceived as feminine.
The weight of eating companions may also influence the volume of food consumed. Obese (BMI >30) individuals have been found to eat significantly more in the presence of other obese individuals compared to normal-weight others, while normal-weight individuals appear to be unaffected by the weight of eating companions.
Note: This post is modified segment from my major revision of the Food Choice Wikipedia page completed as part of the Association for Psychological Science Wikipedia Initiative. For more information about socio-environmental influences on food intake and detailed references, please check out the full Wikipedia entry here.