Research in the Mann Lab

How Can We Promote a Health-Focused Approach to Eating and Exercise?

We believe there are three big questions that must be answered if we are to encourage a health-focused approach to eating and exercise, and we do research on each of them: 

  1. How can we reduce weight stigma and size discrimination? Weight stigma prevents people from taking a health-focused approach (by making them feel they must become thin), and ironically, leads to unhealthy eating and reduced exercise. We are studying whether injunctive norms can be used to reduce the expression of weight stigma. We are also looking into the effects of reclaiming the word fat and giving it a positive connotation.
  2. How can we help people feel satisfied with whatever their body happens to look like once they are engaging in healthy behaviors?  We are currently examining older women to see if their body image changes across their lifespan, and especially if it has less of an influence on their self-esteem and overall wellness than it did when they were younger.  If so, we aim to create interventions in which older women use their wisdom to help younger women keep body image concerns from harming them.
  3. How can we help people stick to regular physical activity, since physical activity improves health regardless of whether it leads to weight loss? This is an exceptionally difficult question to answer, but grad students in the lab are creating and testing a conceptual model that will help us understand and intervene to promote regular physical activity.



Selected Other Projects

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Attention & Self-control

This work was done in collaboration with Andrew Ward (Department of Psychology, Swarthmore College), starting as far back as 1992, when we were grad school classmates together at Stanford. NIH funded this work for ten years (2002-2007 from the National Institute of Mental Health; 2008-2013 from the National Heart, Lung, and Blood Institute).

In this work, we looked at the factors that cause dieters to overeat, and in particular, on how attention both causes overeating and prevents it, depending on the circumstances. It is commonly thought that when people are unable to focus their attention on their goals and behavior, they are likely to lose control – to act in ways that they do not intend or desire. Our research shows that instead of leading to a loss of control, lack of attention simply increases the extent to which people’s behavior is influenced by the most noticeable features of their environment. In cases where the environment contains highly salient reminders of one’s goals (e.g., a scale as a reminder of a diet), individuals who are distracted may control their behaviors better (e.g., eat less) than if they were not distracted. In addition, we have found that there is a certain amount of distraction that helps people control themselves better, even without salient diet reminders present. We have also explored these same processes in people trying to quit smoking.

Increasing Vegetable Consumption in Children

This work was a collaboration with UMN faculty Marla Reicks (Nutrition), Elton Mykerezi (Applied Economics), Joe Redden (Marketing), and Zata Vickers (Food Sciences), and it was funded by the USDA and the Cornell Behavioral Economics and Nutrition Center (B.E.N. Center). We tested a variety of ways to get kids in school cafeterias to eat vegetables. This work was based on the idea that using nudges, or small changes to one’s surroundings, can have larger effects on behavior than efforts to persuade people to change.

Our first nudge was simply placing pictures of vegetables in the compartments of cafeteria trays. This tripled the amount of vegetables elementary school students ate, probably by giving them the sense that everyone else must put vegetables in those sections of the trays and then eat them. Our second nudge was serving carrots to students before they went through the cafeteria line. This also tripled the amount of carrots the students ate, likely by keeping the vegetable from having to compete with the yummier, less healthy foods that they will get in the cafeteria later. We also tested the use of nudges within people's homes, where they had yet to be explored closely.

Preventing Weight Loss in Astronauts

We are excited to have contributed our tiny part to NASA’s research planning for eventual manned missions to Mars. This work was a collaboration with UMN faculty Joe Redden (Marketing) and Zata Vickers (Food Sciences), and it was funded by NASA.

Before NASA can send astronauts to Mars, they must solve hundreds (probably thousands) of different problems that complicate such a monumental task. One very small problem that NASA needs solved is how to prevent astronauts from losing weight on long missions. When astronauts go on missions to the International Space Station, they tend to under-eat and lose weight. Mars missions will be many times longer than missions to the ISS, and this weight loss could therefore be a problem. We attacked this undereating in three ways. First, we did research aimed at preventing astronauts from getting sick of the somewhat limited (but not as limited as you might think!) space diet. We used an intervention that Joe Redden found effective in keeping people from getting sick of songs and from getting sick of jellybeans. Second, we tested whether giving astronauts control of their meals and the opportunity to use creativity in meal preparation reduced their levels of stress, because the stress of space travel is thought to be one reason astronauts under-eat. Related to that point, in our third project for NASA, we tested the effectiveness of eating comfort foods in improving astronauts' moods.

Long-Term Effects of Dieting/Calorie Deprivation on Weight, Self-Control, and Attention

For nearly thirty years we have been studying the long term effects of diets.  We are convinced by what is now a large research literature that diets may lead to short term weight loss, but they do not lead to long-term weight loss. There are many reasons for this, including the effects of calorie deprivation on metabolism, hormones, attention, stress, and self-control.  Those effects make it very difficult (but not impossible) to keep engaging in the behaviors necessary to keep weight off in the long term.

We have explored, for example, the separate and interacting effects of hunger and calorie deprivation on functions or processes related to self-control.  We have found that calorie deprivation makes it harder to control one’s eating, although it doesn’t get in the way of controlling other behaviors. We are also looking closely at how calorie deprivation (from a 10-day restricting diet), hunger (from an overnight fast), and their interaction influence attention.  Do these factors influence what you pay attention to (e.g. food images) and how long your attention stays there?