Researchers View Obesity From a Life Course Perspective

By Segelken, Roger

By looking at the course of individuals’ and groups’ lives over time, researchers can see early warning signs of obesity and determine opportune times for intervention.

The extra pounds and inches that make a body overweight do not appear overnight. The same can be said of the causes and risk factors for an obese population. Researchers agree that it has taken a lifetime of experiences-perhaps several lifetimes across multiple generations-to build the momentum (and mass) that now dooms millions of Americans to a dismal future of ill health.

ln a presentation titled “Obesity and the Life Course” during Cornell’s Ecology of Obesity conference held June 6 and 7, 2005, experts viewed obesity from the life course perspective, which, they said, can reveal both early warning signs and opportune moments for constructive intervention.

The life course perspective brings together psychology, sociology, and human development to examine individuals’ and groups’ periods of stability and periodic changes in beliefs and behaviors over their life spans and over time, according to Elaine Wethington, an associate professor of human development and sociology, and a faculty member of the Bronfenbrenner Life Course Center in the College of Human Ecology. When those beliefs and behaviors involve human health, Wethington adds, the life course perspective helps scientists understand how the environment shapes activity levels, how dietary behaviors change over time, and how people adapt throughout their lifetimes to changing circumstances.

“That’s why studies with children are so important. Childhood is when food preferences are formed, and those preferences will have an impact on health and behavior across the life course,” Wethington said.

Adherents of the life course perspective think in terms of trajectories, pathways, transitions, and turning points, according to Wethington. They try to learn how culture, external events, and what they call contextual influences affect people’s lives, as well as how linked lives-usually within families and workplaces or between partners-have an impact on how people change and adapt.

“Look at how significant others have an impact on health and behavior,” Wethington said, “how parents have impact on how their children eat. Or how your work network has an impact on whether you go out to eat and what you eat. Marital partners have an impact on health and weight and how much you eat and when you eat it.”

The timing of external events-the announcement of a scientific discovery with health implications, for example, or a major change in healthcare protocols-can be important if that event coincides with a critical period in an individual’s life. “You can only adapt in ways that you know at that time, or with the types of strategies that are available to you at your particular age and level of experience,” Wethington noted.

She said the concept of trajectories “has the promise of insights into how eating behaviors develop over time and why change can be so difficult. Studies of when trajectories appear to change suggest when it is easier to help someone; that is, when he or she is in a period of transition.”

Kirsten Davison, assistant professor of health policy, management, and behavior at the University at Albany’s School of Public Health, said she tries to combine knowledge of the “ecology of families” with the life course perspective. To reverse the trend to obesity, Davison said she would provide families “with the skills and support to promote healthy lifestyles among all family members. This is the key place we need to start in the prevention of obesity, and we need to start early. Eating behaviors, physical activity patterns, and TV viewing habits develop early in life, in the context of the family, before children enter school.”

Early habits show continuity across time, according to Davison, “and they are more difficult to change as time elapses and habits become ingrained. Parents pass on the genes related to regulation of body weight and they create the environment in which young children live and grow; parents really load the gun and then they pull the trigger.”

Davison’s prescription for a healthy family environment calls for more healthful foods and less junk foods, more physical activity involving the entire family, and less television watching. “Parents themselves need to develop healthy eating behaviors because there is a trickle-down effect,” she said. “Making a variety of healthful foods available and accessible in the home will increase the likelihood children will consume and learn to prefer these foods.”

A mother with young children, Davison recommends continuing to offer healthful foods even though the child rejects it at first. “Among infants, preference for vegetables can take up to eight exposures before a baby will actually accept these vegetables. Physical activity can be encouraged by facilitating children’s participation in organized events and incorporating physical activities in family time,” she said. “Instead of watching a movie together, go for a bike ride or go roller blading.”

Appalled by a recent finding-that 40 percent of American preschoolers have personal television sets in their bedroomsDavison said parents should limit their own TV viewing, remove television sets from children’s rooms, and place clear limits on how much television children can watch.

Stephen Cook, a specialist in pediatrics and internal medicine at the University of Rochester, takes a biological perspective on the changes that occur throughout lifetimes. Two changes in particular worry him: the development in individuals of the so-called metabolic syndrome and the tendency for components of the metabolic syndrome to show up in younger and younger populations, including adolescents.

The World Health Organization (WHO) defines metabolic syndrome as a clustering of risk factors around insulin resistance and obesity- including abdominal obesity, glucose intolerance or insulin resistance, elevated blood pressure, and lipid abnormalities.

“Metabolic syndrome has emerged as being as strong a contributor to heart disease as cigarette smoking,” Cook said.

“It is important to recognize the syndrome and treat it with lifestyle changes,” he said, adding that approximately 25 percent of American adults are affected by metabolic syndrome.

Even more worrisome to pediatrics specialists such as Cook is the early onset of metabolic syndrome in children. “The rate of increase in children with Type 2 (adult) diabetes is devastating,” he said. “In adults, the risk factors [for metabolic syndrome] can take decades to accumulate. In adolescents, we’re seeing some risk factors in just years or months. Children are definitely laying down cholesterol and laying it down in greater degrees than adults.”

Psychological and environmental stresses also can be predictors of metabolic syndrome in children, Cook noted. “Children who score higher on scales for hostility and psychological stress have higher BMIs [body mass indexes] and higher rates of insulin resistance.” Survivors of childhood cancers are particularly susceptible to metabolic syndrome, Cook said, and smoking or exposure to tobacco smoke also is a risk factor.

Treating metabolic syndrome in adults requires multiple medications and help to make behavior changes, Cook observed. So prevention-as early as childhood-”is hugely important. If parents have a clustering of metabolic syndrome factors, their children are much more likely to have inherited or acquired those factors, too,” he said.

One kind of psychological stress is the experience of “growing up poor,” according to Christine Olson, the Cornell professor of nutritional sciences who helped conduct a multistate study of the links between obesity and poverty.

The study, which was conducted in part in two upstate counties in New York, found that mothers who were poor as children were twice as likely to be overweight or obese than women who had grown up in families who were not poor. One preliminary conclusion of the study is that socioeconomic status-related differences in parenting practices lead to behavioral patterns in childhood, and throughout life, that increase risk of obesity. Binge-like eating patterns, for example, were more common in mothers who had grown up poor.

Olson said that interviews with participants in the poverty- obesity study revealed some lasting effects of growing up poor. “One woman told us, ‘i panic when there is no food in the house. When it is there, I am calm.’ She said she remembered the deprivation when her father’s factory went on strike, and now she obsesses about shortages of food, particularly when she perceives an economic threat. People told us they were happy when the cupboard was full. They had developed an emotional attachment to food.”

The nutritional scientist said some people who had experienced food insecurities and deprivation in childhood compensate as adults by “stocking” more food than they need. “One woman said she always has a garden and the freezer is never empty. She bargain shops in big lots. She told us, ‘I will never be hungry again. I’ve been through it and it’s not fun.’”

The study found adults had developed eating habits “in response to negative affective states in their youth,” Olson said. “We heard one woman say, ‘When my sister and I were grow\ing up, there were times when we went to bed with nothing. And it wasn’t my mother’s fault. She worked hard.’ When food became available, she would eat until she ‘had a big stomachache. Then we would sleep.’ She had an awareness that now, today as an adult, when things get tough, she is doing the same things because she remembered the pleasure and relief she got from overeating. Eating would calm her down, almost like a sedative.”

Of particular interest to the nutritional scientists conducting the poverty-obesity study is how a second generation of poverty affects today’s children. She said one father told of coaching his children through weeks of lean times and encouraging them to anticipate the last week of the month when their family would have enough money to buy food. “That excitement and pleasure, when food does become available, can lead to overeating,” Olson said.

Growing up in the context of poverty and food deprivation may well be predisposing today’s children to develop obesity in adulthood. “During adult life, food insecurity and other life stresses may trigger a reversion to emotional eating patterns and overeating learned in childhood,” Olson noted.

From the life course perspective, Wethington would say the children of poverty are following a behavioral trajectory that was created in childhood. “A trajectory is a stable pattern, in this case a pattern characterized by a lifestyle relating to health or progress toward chronic disease. A trajectory has momentum; it has stability. And while there can be multiple trajectories in an individual person’s life, trajectories tend to be consistent and to reinforce one another. But trajectories can change, ” Wethington said. “There can be transitions and turning points. Events that occur in the environment can change trajectories.”

Public health interventions to break the obesity cycle could well start with families, according to Davison. “There are a number of ways parents can influence children’s obesity-related behaviors,” she said, “including knowledge and beliefs of the parents, modeling, and shaping.”

Gary Evans, Human Ecology professor of design and environmental analysis, who was a responder to the presentations, quoted B. F. Skinner as saying, after a career devoted to shaping behavior: “It is much easier to change the environment than to change behavior.” Public health professionals, including faculty in the College of Human Ecology, are initiating environmental approaches to obesity prevention. Several of these are described in this issue of Human Ecology.

FACT

Did You Know?

Parents pass on the genes related to regulation of body weight and they create the environment in which young children live and grow.

Olson said that interviews with participants in the poverty- obesity study revealed some lasting effects of growing up poor.

One woman told us, ‘I panic when there is no food in the house. When it is there, I am calm.”

more information?

Elaine Wethington

Cornell University

ew20@ornell.edu

Kirsten Davison

University at Albany

kd878362@albany.edu

Stephen Cook

University of Rochester School of Medicine and Dentistry

stephen_cook@urmc.rochester.edu

Christine Oison

Cornell University

cmo3@cornell. edu

Gary Evans

Cornell University

gwe1@Cornell.edu

Copyright Cornell University Dec 2005