Capturing a Moment

How does the immediately availability of highly palatable foods influence caloric intake? Does this differ among different people and if so how? A study published in the journal Obesity by Thomas et. al. suggests that individuals with a higher BMI are more likely to overeat when there is an abundance of tasty food that is easily accessible compared to individuals with a lower BMI.

While some may conclude that the results of this research are no more than common sense, these findings are unique because of the methodology used, a study format called “Ecological Momentary Assessment” (EMA). Most studies that look at diet and eating patterns use recall methods, where subjects are required to remember what, how much, and when they ate at a previous moment in time. In EMA, subjects are sent a message (in this study it was via handheld computers) that prompts them to answer a specific question or questions at a specific moment in time. Subjects then are required to answer as soon as possible (reminders are sent until a response is received). The other advantage is that this method studies individuals in their natural environment, and not a laboratory setting.

The authors investigated three hypotheses:

  1. Does an increased number of tasty, high calorie foods leads to an increase in eating more than normal?
  2. Are individuals who are more sensitive to the rewarding aspects of food (as measured by the Power of Food Scale) more likely to over-consume?
  3. Are individuals who scored higher measures of restraint more likely to resist over eating when presented with an increased availability of tasty, high calorie foods?

During an initial interview, subjects completed two questionnaires that looked at “restraint” (how much control an individual exerts over their eating) and “hedonic eating” (the desire to consume highly palatable foods): the Three Factor Eating Questionnaire and the Power of Food Scale. After an orientation in which subjects were instructed on how to use the hand-held computer as well as given guidance in identifying their normal pattern of food intake, subjects completed 7-10 days of EMA assessment. During the study, subjects received prompts via a hand-held computer to answer several questions about their most recent eating experience.

The results surprised the investigators – none of their predictions were supported by the evidence. The only significant relationship was that individuals with a higher BMI were more likely to consume more food than they normally would when there was an increase in the number of high palatable foods available compared to individuals with a lower BMI. Interestingly, the probability of overeating when high calorie tasty foods were not easily accessible was low, regardless of BMI.

The study only included young women who were in a healthy BMI range, so any conclusions must be limited to eating habits and cannot be extrapolated to risk of overweight or obesity. As the authors mention, it would be interesting to repeat the study to include a wider range of weights. Use of BMI as a measure also has its limitations, especially with a small sample size. I’m also curious if the intrusion of having to respond to the questions of the ecological momentary assessment influences the behaviour of the subjects? If subjects know that the number of times they overeat is being assessed, might they eat less?

Capturing the moments at which we make decisions related to food intake through studies such as this offers better understanding of  the reasons for over-eating. This information, combined with Brian Wansink’s and colleagues’ work on mindless eating, is invaluable for identifying strategies that will be most helpful to individuals wishing to make health related behaviour changes.

ResearchBlogging.org

Thomas JG, Doshi S, Crosby RD, & Lowe MR (2011). Ecological momentary assessment of obesogenic eating behavior: combining person-specific and environmental predictors. Obesity (Silver Spring, Md.), 19 (8), 1574-9 PMID: 21273995

Image by jeffadair from Flickr.

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