How Childhood Trauma Can Cause Adult Obesity

Dr. Vincent Felitti, founder of Kaiser Permanente’s Department of Preventive Medicine and director of its obesity-treatment program, was seeing some good results. His patients were losing 50, 80, even hundreds of pounds. He might have considered the program a success, if not for the fact that the participants who were doing the best — those who were both the most obese and losing the most weight — kept dropping out.

Felitti was baffled. Why, invariably, did so many patients quit just as they approached their healthy goal weight? Ella, for instance, a middle-aged woman who entered the program in the mid-1980s morbidly obese at 295 lb., had managed to whittle her frame by 150 lb. over six months. “Instead of being happy, she was having anxiety attacks and was terrified,” Felitti says.

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He asked Ella what she thought was going on. “Finally, the story comes out,” he says. “She had been molested as a child, both within her family and outside it. She tried to escape by marrying at 15, at her mother’s urging. It was a disastrous marriage — her husband was crazy jealous. They divorced in two years. She remarried. Her new husband was also jealous. He was convinced that when she was out hanging the laundry, she was sexually posturing to attract the neighbors.”

When Ella was overweight, Felitti learned, her husband was less suspicious. And her fear of his rage — perhaps he saw her new slimmer weight as a provocation? — was probably spurring her anxiety.

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Felitti wondered if there was something similar barring weight loss in other patients — or causing obesity itself. In the late ’80s, he began a systematic study of 286 obese people, and discovered that 50% had been sexually abused as children. That rate is more than 50% higher than the rate normally reported by women, and more than triple the average rate in men. Indeed, the average rates of sexual abuse are themselves unsettling: according to a large 2003 study conducted by John Briere and Diana Elliott of the University of Southern California, 14% of men and 32% of women said they were molested at least once as children.

In recent years, studies by both Felitti and others have largely confirmed the association between sexual abuse — as well as other types of traumatic childhood experience — and eating disorders or obesity. A 2007 study of more than 11,000 California women found that those who had been abused as children were 27% more likely to be obese as adults, compared with those who had not, after adjusting for other factors. A 2009 study of more than 15,000 adolescents found that sexual abuse in childhood raised the risk of obesity 66% in males in adulthood. That study found no such effect in women, but did find a higher risk of eating disorders in sexually abused girls.

Discoveries by Felitti and colleagues have also helped give rise to broader work linking stressful experiences early in life — as early as in the womb — to effects on health and behavior later on, such as an increased risk of heart disease or becoming addicted to drugs. Scientists are finding that such effects are not only long-lasting, but can even be inherited by future generations.

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In decades of experiments with rats, for instance, neuroscientist Michael Meaney at McGill University in Canada and his colleagues have shown how such environmentally induced traits can be passed down — then undone, also by environment. Meaney studied rats with differing maternal styles — some were naturally nurturing (they licked and groomed their pups constantly), others were less attentive and even neglectful (mother rats placed in stressful environments like isolation had greatly decreased capacity for nurture). What researchers found was that these behavioral traits were passed down to future generations: pups born to neglectful mothers endured stressful childhoods and grew up to become neglectful mothers themselves. But when babies born to stressed or less attentive mothers were instead placed with nurturing, affectionate mothers, that early experience changed the pups. They adapted quickly to the new mothering style and grew up to tend carefully to their own offspring. These pups’ adaptation was then passed to successive generations as well.

When Felitti first presented his Kaiser Permanente data connecting obesity with child molestation at a national meeting on obesity in 1990, most colleagues dismissed him immediately (one even claimed that obese people made up such stories to justify their “failed lives”). David Williamson, an epidemiologist at the Centers for Disease Control and Prevention (CDC), was the lone exception. He said that a large epidemiological study was needed to determine whether there were any implications of Felitti’s findings for public health.

Felitti knew that he had just the right data set: Kaiser Permanente has the largest medical-evaluation facility in the developed world, diagnosing some 58,000 patients annually. Even if only a minority agreed to discuss their childhoods and allow anonymous use of their medical records, that would be a huge sample. And so the Adverse Childhood Experiences (ACE) study was born, as a collaboration of Felitti and another CDC researcher, Dr. Robert Anda.

For the past several decades, the ACE study has recorded reports of negative childhood experiences in more than 17,000 patients. Adverse experiences include ongoing child neglect, living with one or no biological parent, having a mentally ill, incarcerated or drug-addicted parent, witnessing domestic violence, and sexual, physical or emotional abuse. The researchers then searched for correlations between these experiences and adult health and the risk of disease.

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The connections became clear: compared with a person with no adverse childhood experiences, or ACEs, a person with four or more has almost double the risk of obesity. Having four or more ACEs more than doubles the risk of heart attack and stroke, and nearly quadruples the risk of emphysema. The risk for depression is more than quadrupled. Although many of these outcomes could reflect the influences of genes and other environmental influences — beyond those occurring in childhood — the tight relationship between increasing ACE numbers and increasing health risks makes the role of child trauma clear. Dr. Jack Shonkoff, director of Harvard’s Center on the Developing Child, calls the research “a tremendous contribution.”

But how does the psychological experience of childhood neglect cause physical effects like obesity, heart attack or stroke? There are at least two interconnected pathways — one physiological, the other psychological.

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The psychology is relatively straightforward: being abused or otherwise traumatized is painful, and food can be a numbing or comforting escape. Hence, abused children may turn to overeating, which causes obesity. Indeed, ACEs are also strongly linked with other types of unhealthy “self-medication”: for instance, cigarette smoking (which accounts for the increased rate of emphysema among high ACE scorers) and drug abuse (having four or more ACEs increases the risk of injectable-drug use by a factor of 10). As Felitti puts it, “Being fat [or having other unhealthy behaviors] is not the problem. It’s the solution.”

The psychological effects often exacerbate health problems that the physiological stress response has already caused. High ACE scorers who do not overeat, smoke or take drugs still have high rates of obesity, heart disease, depression and diabetes. The mechanism for these risks appears to lie in the biology of the stress-response system and in the way environment affects a person’s genetic activity.

For most of human evolution, a stressful world would have been marked by famines or periods of starvation, and that environment might have resulted in a particular pattern of gene expression that would have prompted the body to store more fat in preparation for the next bout of scarcity. Today, of course, the same response to stress would result in obesity. This theory of a thrifty fat-storing system that kicks in under high levels of early stress was originally proposed by British physician David Barker.

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If, for instance, a modern child’s early life experience — in the womb and during the first five years, particularly — is constantly stressful, it would be incredibly energy-consuming, says Dr. Bruce Perry, senior fellow at the ChildTrauma Academy. “If your genes get the message that you are entering a stressful world, it makes complete adaptive sense to take the existing metabolism and tune it up to deposit fat and store energy to prepare for what the body is expecting will be a challenging and stressful life,” he says.

“Early adverse experience can disrupt the body’s metabolic systems,” says Shonkoff. “One of the cornerstones of biology is that our body’s systems when they are young are reading the environment and establishing patterns to be maximally adaptive.”

Researchers also posit that high levels of stress hormones caused by ACEs can wear down the body over time. A temporary spike in blood pressure in response to a stressful event may be useful to power an adaptive fight-or-flight response, but over the long term constant high blood pressure could raise a person’s risk for heart attack and stroke. Studies have also found that consistently elevated levels of stress hormones, like cortisol, can lead to permanent damage in certain brain regions linked to depression.

Recently, scientists have discovered that these changes can themselves be passed down from one generation to the next — a burgeoning new area of study called epigenetics. Such research may have significant and long-term implications for the prevention of obesity, addiction and other illnesses related to early life stress. After all, reducing childhood exposure to trauma in one generation may further benefit that generation’s children and grandchildren.

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Some initiatives, such as the nurse home-visiting program and President Obama’s proposed Promise Neighborhoods program, already put this theory into practice, by offering support and services to low-income parents in order to reduce child abuse, increase access to prenatal care and provide parenting education and high-quality day care.

The goal is not only to improve conditions for the current participants of such programs, but also hopefully to reduce the risk of problems in successive generations, including major causes of death and disability like obesity, heart disease and stroke. “It’s not a secret that there is a growing epidemic of obesity and there’s no question that the way we eat and the way we exercise, or do not exercise, is contributing to it. But it’s a huge mistake to attribute it just to the need to close down fast-food restaurants and turn off the TV. There’s important biology here early in life that needs attention,” says Shonkoff.

Szalavitz is co-author, with Dr. Bruce Perry, of the forthcoming Born for Love: Why Empathy Is Essential and Endangered

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