Why Obese Children Become Obese Adults

Were you overweight or obese as a child? The majority of morbidly obese patients presenting for Bariatric surgery have been obese since childhood. One study reported that nearly 85% of their morbidly obese surgical population had childhood onset obesity. Our own studies found that 3 out of 4 morbidly obese patients have been obese since childhood and nearly one-third of these since infancy.

Altogether, the findings suggest that fatness in childhood may not only carry over into adulthood but also give rise to a more severe form of obesity. Several studies have found an association between age of obesity onset and levels of obesity among adults. According to these reports, adults who have been obese since infancy or early childhood are larger than those who become obese later in life.

There are also several retrospective and long-term investigations that have studied the risk that childhood obesity will carry over into adulthood. A meta-analysis (overall assessment) of data from several of these studies determined that approximately 50% of obese children will remain obese as adults.

One long-term (average follow-up = 17 years) study of a biracial population of more than 2000 children (ages 2 to 17 years) from Bogalusa, LA (The Bogalusa Heart Study) found that an exceptionally high percentage of obese children become obese adults. According to their findings, 77% of overweight children remain obese as adults.

Why is the risk for adult obesity so high among overweight children? Genetics, poor lifestyle behaviors, and various metabolic, hormonal, and psychological consequences of weight gain per se strongly increase the likelihood that childhood obesity will persist into adulthood.

Parental obesity is one of the more important risk factors of childhood obesity. Parental influence on obesity not only results from shared genes but also from a shared lifestyle including diet, food preferences, leisure activities, and other behaviors that influence body size.

Several studies have found that poor nutritional and exercise habits established in childhood track into adulthood. Diets high in sugar, processed grains and fat and low in dairy products or dietary fiber (fruits, vegetables, legumes, nuts) contribute to obesity. Watching too much television and other sedentary activities also contribute to the onset of obesity in children and such habits developed in childhood carry over into adulthood, along with obesity risk.

Weight gain during childhood and the social stigma attached to such has psychosocial consequences that may also increase the risk for further weight gain and long-term obesity. Psychosocial consequences of early onset obesity include low self-esteem, a poor self-image, depression and anxiety. These conditions, in turn, are associated with an increased incidence of binge eating, emotional overeating, high carbohydrate craving, yo-yo dieting, and other aberrant eating patterns that promote weight gain or reduce weight loss success.

The psychosocial consequences of childhood obesity, including low self-esteem, depression, anxiety, and a poor self-image, often track into adulthood. One study found a much higher incidence of depression and anxiety among postmenopausal women with early onset obesity, as compared to those with adult onset obesity. Another study found that women who were obese as teenagers had greater depression, less education and were more likely to have married below the economic status of their parents than were their leaner classmates. Still other studies reported the persistence of low self-esteem and distorted self-image among adults with childhood onset obesity even after normalization of body size with dietary or surgical intervention.

Data from the Bogalusa Heart Study, mentioned earlier, found that weight gain during childhood increases insulin levels and that elevated insulin levels in childhood track into adulthood. High insulin levels increase the risk for childhood or adult obesity by reducing the amount of fat the body burns for energy, increasing the uptake and storage of fat, and inhibiting fat breakdown.

Weight gain or obesity during post-pubertal adolescence may be associated with additional defects in hormone production or actions that favor fat accumulation and further weight gain. These defects include low growth hormone production, low levels of dehydroepiandrosterone (DHEA), increased production of cortisol, and disturbances in the production of sex hormones.

Childhood obesity, according to several reports, increases total fat cell numbers, along with fat cell size. Studies of obese children and adults have found that individuals with high fat cell numbers have difficulty controlling their body weight and maintaining weight loss.

Obesity during childhood may promote further weight gain with increased risk for adult obesity by lowering levels of physical activity and, consequently, total number of calories the body burns. Joint pain and fatigue reduce the desire for physical activity, as would the occurrence of any one of a number of obesity-associated diseases, such as diabetes, hypertension, obstructive sleep apnea, depression and others. Furthermore, many of the medications used to treat such diseases promote further weight gain, including insulin and sulfonylureas used to treat diabetes, beta-blockers for hypertension, and anti-depressants including tricyclics, lithium, and even serotonin reuptake inhibitors (when used long-term).

As is apparent from the above discussion, there are numerous conditions associated with childhood obesity that promote further weight gain and impede weight loss success, thereby, increasing the risk that obesity will persist into adulthood. These same conditions may also cause the individual with early onset obesity to be less responsive to anti-obesity treatments.

Some studies have found that individuals obese since childhood lose less weight with diet than do those with adult onset obesity. Other studies, however, found similar amounts of diet-induced weight loss between individuals with childhood and adult onset obesity. Still other investigators found that individuals with childhood onset obesity are even more successful in losing weight with short-term conventional weight loss therapy. Childhood obesity may, therefore, not interfere with one’s ability to lose weight as an adult.

Childhood onset obesity, with of its many behavioral, psychosocial, and physiological co-morbidities, however, may affect one’s ability to maintain weight loss long-term. Several studies have shown that individuals with childhood onset obesity not only have greater difficulty maintaining weight loss following anti-obesity treatments but also tend to regain even more weight than initially lost.

These findings may explain why, in part, the morbidly obese, with their high prevalence of childhood obesity, have lost hundreds of pounds on conventional weight loss treatment regimens, only to regain all of their weight plus more. Furthermore, such findings may underscore the need for more aggressive weight loss therapy, including surgery, in providing long-term weight loss success for seriously obese individuals who have been overweight since childhood.

Cynthia K. Buffington, Ph.D. Dr. Buffington is the Director of Research for U.S. Bariatric in Ft. Lauderdale, Orlando and Miami, FL