Early Recognition of Overweight and Obesity
The healthcare sector can play a critical role in addressing obesity and overweight in both children and adults. The medical community has been given the charge by the U.S. Surgeon General (2001) and provided guidelines by the National Institute of Health (NIH) Obesity Education Initiative (1998), the American Academy of Pediatrics (AAP) (2004), the American Heart Association (AHA) (2004) and the World Health Organization (WHO) (2004) to take actions targeting the obesity epidemic.
The Online Course on Preventing Childhood Overweight is an interactive, web-based continuing professional education program for nutrition and health practitioners. As part of Cornell NutritionWorks, a new online course on "Preventing Childhood Overweight at Home, at School, and in the Community" is being developed, which will be pilot tested in the spring 2005. This course will build upon the growing number of offerings already available on Cornell NutritionWorks related to childhood overweight. Cornell NutritionWorks provides a convenient, accessible form of continuing education to busy professionals to increase their capacity to address nutrition issues such as childhood obesity at the community level.
Cornell NutritionWorks was developed by Cornell University Division of Nutritional Sciences faculty in 2002 to meet the professional development needs identified by community practitioners. In addition to the opportunity to interact with Cornell faculty members, Cornell NutritionWorks provides access to current nutrition research, references and tools that enhance practice, discussion forums for exchanging information with peers, and self-assessments for continuing professional education units. Membership in Cornell NutritionWorks became free in 2004. There are currently over 1,300 members, from all 50 states and 28 countries. There is a small fee for credits, which can be paid online. Current funding for Cornell NutritionWorks comes from Cornell Cooperative Extension, the College of Human Ecology at Cornell, and the Offices of the President and Provost at Cornell.
These professional organizations have issued statements providing professional guidelines for screening, diagnosing and managing obesity, strategies to aid in preventing the development of overweight, and recommendations to routinely counsel patients about healthy eating and physical activity, and/or obesity. A number of reports, however, suggest that these guidelines are often not being implemented. Insufficient reimbursement, lack of time for counseling, and lack of access to qualified dietitians are often cited as reasons why not (Robinson and Killen, 2001). Moreover, there is often a perceived lack of interest and/or motivation by patients or parents and a sense that treatment is futile. In fact, the high rate of recidivism associated with weight loss programs (95% of individuals regain weight lost within three years), has contributed to the call for efforts focusing on prevention of overweight (Hill and Peters, 1998).
Most pediatric care providers do not routinely use BMI percentiles to track children's growth or to screen for overweight, despite recommendations to do so (Barlow and Dietz, 1998; CDC; AAP, 2003). A recent study found that older children and adolescents, and those who are more overweight were most likely to be diagnosed, have further evaluation, be referred for dietary counseling, and have closer follow-up (O'Brien, Holubkov, Reis, 2004). Given that most medical providers do not recognize or discuss childhood obesity with parents, it is not surprising that three quarters of parents do not recognize their overweight child as such (Jain et al., 2001; Dennison et al., 2000). Moreover, subpopulations with higher prevalence rates of childhood obesity (i.e., low-income mothers and Hispanics) were less likely to recognize that their child was overweight. A recent study also found that less than half of obese adults report being advised to lose weight by healthcare professionals (Galuska, 1999). Healthcare providers who are not overweight, have healthy eating habits, and who exercise regularly are more likely to discuss obesity or weight status with patients than those who are not or do not (Lewis, Wells, 1986). Providers are also more likely to counsel women than men, high income vs. lower income patients, patients younger than 65 years vs. those over 65 years, and who are severely obese (Taira, Safran, Seto et al., 1997; Galuska, 1999). Yet, patients who are counseled to lose weight are more likely to report trying to do so (Galuska, Will, Serdula et al., 1999; Nawaz, Adams, Katz, 1999).
Critical Periods for Excess Weight Gain
There appear to be periods in life when the risk of developing obesity is higher-the pre-natal period, the period in early childhood prior to the "adiposity rebound" and adolescence. Hypothesizing that certain environmental exposures (i.e., excess caloric intake) are more likely to result in excess weight gain at certain developmental stages than at other times, they have been referred to as "critical periods" (Dietz, 1994, 1997). Recent studies suggest that early infancy may also be a critical period relating to the later development of obesity. A number of studies report that rapid infant weight gain during the first 4 to 6 months of life is associated with an increased risk of being overweight later in childhood or young adulthood (Edmunds; Stettler, Zemel, Kumanyika, Stallings, 2002). In addition to biological factors, parental and family factors during these periods may be critical in determining weight status later in life.
The prenatal period
A number of studies have found that higher birth weight is associated with higher attained BMI during later childhood and adulthood (Allison, Paultre et al., 1995; Barker, Robinson et al., 1997; Charney, Goodman et al., 1976; Kramer, Barr et al., 1985). Maternal obesity is also related to higher birth weight, unhealthy weight gain and obesity, supporting the theory that genes shared between mothers and children determine both birth weight and later obesity.
Several studies have noted an inverse association of birth weight with increased later weight gain and measures of abdominal obesity in both childhood and adulthood (Barker, Robinson, et al., 1997; Law, Barker et al., 1992; Okosun, Liao et al., 2000; Valdez, Athens et al., 1994; Kuh, Hardy et al., 2002), and measures of insulin resistance and the metabolic syndrome, after adjustment for attained BMI (Hulman, Kushner et al., 1998; Valdez, Athens et al., 1994; McCance, Pettitt et al., l994; Mi, Law et al., 2000; Phillips 1998; Vanhala, Vanhala et al., 1999).
WIC monitors weight during pregnancy and throughout the postpartum period (one year for breastfeeding women). Nutritional risk eligibility is determined based on federally-mandated nutritional risk criteria. Prenatal risks include pre-pregnancy overweight, and high maternal weight gain. Postpartum risks include breastfeeding less than 6 months postpartum with pre-pregnancy BMI greater than or equal to 25, and breastfeeding more than 6 months postpartum with a postpartum BMI greater than or equal to 25. The WIC BMI risk level has recently been lowered from 26.1 to 25. More women in the WIC program will now be identified as overweight, and therefore, more women will receive counseling or education.
Prenatal weight gain and long-term obesity
Pregnancy can have a significant impact on women's long-term weight and risk of being overweight. Nulliparous women tend to be less overweight compared to multiparous women, and there is a dose-response effect: the more children a woman has, the more likely she is to be overweight. In the past, the primary focus of prenatal nutrition counseling was to prevent deficiencies. Today the growing epidemic of obesity and associated chronic illnesses has drawn attention to the problem of over-nutrition during pregnancy, leading to excessive gestational weight gain and postpartum weight retention. In 1990, the Institute of Medicine (IOM) issued guidelines for gestational weight gain based on a woman's pre-pregnancy Body Mass Index (BMI). They recommended that women who weigh more (i.e., have a higher BMI) gain less weight during pregnancy than women who weigh less. Gaining more weight than the IOM guidelines increases a woman's risk of retaining (i.e., not losing) the extra weight gained during pregnancy and increases their risk of being overweight or obese with each subsequent pregnancy. Lower income women with pregnancy weight gains above the range recommended by the IOM guidelines retained 8.2 pound more at one year postpartum than lower income women who gained within the range. They were also 4.7 times more likely to experience major weight gain with childbearing (Olson et al., 2003). In the U.S., few women stay within the IOM guidelines. Therefore, excessive gestational weight gain is an important preventable cause of overweight among adult women in the U.S.
An Approach to Promoting Healthy Body Weights in Childbearing Women
Christine M. Olson, Professor
Division of Nutritional Sciences, Cornell University
Description of Program: The long term goal of this project is to decrease the amount of weight retained in the postpartum period by lower income, rural women who enter pregnancy with normal or high body mass indices (BMI). This goal was addressed by encouraging women to gain an amount of weight during pregnancy that is within the appropriate ranges recommended by the Institute of Medicine (IOM). The intervention was implemented in the hospital and clinic system of Bassett Healthcare serving eight counties in Upstate New York. Health care providers monitored women's gestational weight gain using adapted IOM gestational weight gain grids and drew their attention to the optimal range of gestational weight gain. Women were provided with a tool for self-monitoring of weight gain and encouraged to use it by health care providers. In addition, they received five action-promoting newsletters in the mail that include post cards on which they set goals and had the opportunity to ask questions that were answered in the next newsletter.
Evaluation of the Program: Two hundred eight pregnant women entered the intervention cohort and 179 were included in the analytical sample. These women were compared to 381 high and normal BMI women who participated in an observational study of postpartum weight retention in the same health care facility (historical control group). Overall, the intervention had no significant effect on the proportion of women who gained more weight in pregnancy than the IOM recommends (45 percent control group vs. 41 percent in the intervention group). However, among low income women, it had a significant effect on excessive gestational weight gain. Fifty-one percent of the low income control group women gained more than the recommended amount compared to 33 percent in the low income intervention group (p < 0.01). The impact of the intervention among low income women was present in both the normal and overweight groups. Women were followed until one year postpartum. In the low income sub-sample, overweight women in the intervention group were significantly less likely to retain 5 or more pounds than similar women in the control group (p = 0.04).
The period of "adiposity rebound"
In general, a child's BMI increases rapidly during the first 6 to 12 months of life, but then decreases until 4 to 8 years before rising again into adulthood. Children who reach their BMI nadirs (low points) at a younger age have an earlier "adiposity rebound" and have a greater risk of obesity one to two decades later (Rolland-Cachera, Deheeger et al., 1984, 1987; Freedman, Kettel Khan et al., 2001; Whitaker, Pepe et al., 1998; Williams, Davie, Lam, 1999).
Older children and adolescents
While the pre-teen and teenage years may not constitute a truly critical period, they appear to be quite important in the life course development of obesity. Whitaker and colleagues (1997) have shown that children who are obese between 10 and 17 years of age are about 20 times as likely to remain obese into young adulthood compared to their non-obese counterparts. Puberty is a time of rapid acceleration and deceleration of height growth; relative weight changes tend to be rapid as well. In girls early menstruation is associated with obesity (Laitinen, Power, Jarvelin, 2001). While boys in general do not gain as much overall fat as girls during the teenage years, the tendency towards developing abdominal fat may be more pronounced in boys (Goran et al., 1995).
In girls, the decline in physical activity during the adolescent years may play an important role, possibly explaining the greater weight gain over 10 years of follow-up among black girls compared to white girls (Kimm, Glynn et al., 2002; Kimm, Barton et al., 2001).
The genetic contribution to obesity has long been recognized. However, the rapid changes in obesity prevalence over the past 30 years cannot be due to genetic changes, which take thousands of years to manifest. Parents today are twice as likely to be obese as 30 years ago (IOM, 2004). Parental obesity more than doubles the risk a child will be obese as a young adult, while having two obese parents increases the risk tenfold compared to having two non-obese parents (Whitaker et al., 1997). Thus, children from families with obese parents are at high risk of developing obesity.