Robert Karp, MD
SUNY Downstate Medical Center
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PRE-TEST (detailed explanations at the bottom):
Q1. True or false: The age for Adiposity Rebound is similar for children at the lower percentiles for BMI as it is for those children at higher percentiles.
Q2. Which of the following times is accumulation of body fat unlikely?
a. Up to 7 months of age.
b. From one to 4 years of age
c. From four years to adolescence
d. In adolescence?
Q3. True or False: The Adiposity Rebound is a universal phenomenon for preschool age children.
Q4. Which is the most important for prediction of obesity in later life?
a. The age at which AR occurs
b. The percentile for BMI at two years of age
c. The rate of rise of BMI from six months to one year of age
d. None are more important than another
OBJECTIVES
After completing these modules, residents will be able to:
1. Define the phenomenon of Adiposity Rebound.
2. Know the ages at which it occurs.
3. Recognize that in previously starved populations there is no Adiposity Rebound.
4. Recognize the risks for obesity and metabolic syndrome later in life.
5. Provide appropriate counseling for pre school age children and their parents.
FACILITATOR PREPARATION
1. Rolland-Cachera MF, Deheeger M, Bellisle F, Sempe M, Guilloud-Bataille M, Patois E. . Rebound in children: a simple indicator for predicting obesity. Am J Clin Nutrition. 1984;39:129-35 – first observation
2. Whitaker RC, Pepe MS, Wright JA, Seidel KD, Dietz WH. Early adiposity rebound and the risk of adult obesity”. Pediatrics. 1998;101(3):E5
3. Williams S, Dickson N, Early growth, menarche, and adiposity rebound. Lancet.
2002 ;359:580-1.
4. Bhargava SK, Sachdev HS, Fall CHD, et al. Relation of Serial Changes in Childhood Body-Mass Index to Impaired Glucose Tolerance in Young Adulthood. NEJM 2004;350:865-75.
5. Dietz W. (1999 and 2005) Childhood obesity (in) Shils, ME, JA Olson, M Shike, and AC Ross. (eds) Modern nutrition in Health and Disease, 9th edition. Lippincott Williams and Wilkins, Baltimore, MD. pp 1071-1080 and..10th edition pp 979-990. Dr Dietz is Chair of the CDC obesity Section at the NIH. PubMed will provide his latest contributions to the literature.
6. Allison D.B, Matz PE. Pietrtobelli A, et al. (2001) Genetic and environmental influences on obesity (in) Bendich A, Decklebaum RJ. Primary and Secondary Preventive Nutrition. Humana press. Teaneck, NJ
INTRODUCTION
New fat cells and body fat accumulation occurs during three phases in a child’s life. The first (early infancy) and third (in adolescence) are well recognized. The phenomenon of “adiposity rebound" (AR), a rise in BMI and body fat storage, occurring between 4 and 7 years of age, is often not recognized as a phase of normal growth in childhood. The AR is generally considered essential preparation for the pubertal growth spurt that will occur 4 to 8 years later. Of note, Dietz prefers the descriptive term “BMI Rebound” due to the fact that data showing increase in body mass is actually from fat, are not conclusive. We continue to use the term “Adiposity Rebound" with recognition that the source of the gain might not be fat.
One theory for the occurrence of an AR is that the body is being prepared for the adolescent growth spurt. With that theory in mind, finding differences in timing of the AR between boys and girls would not be surprising. In fact, AR does occur earlier in girls than in boys — 4 years of age for girls and 4.4 years in boys, both at the 95th percentile. The female accumulations of weight and growth spurt are have been related to the timing of menarche. Excessive exercise as in athletes or people with eating disorders limits weight gain and delays menarche.
There are also differences found for children likely to be lean or obese later in life. An AR as early as 4 to 4 –1/2 years of age is associated with adult obesity. Adiposity Rebound occurs at 7 years of age for both boys and girls at the fifth percentile at that age. These children tend to stay lean. Of note the spread between the 50th and 95th percentiles for BMI is substantially greater than the spread between the 5th and 50th percentiles. Comparison between data from the current epidemic of obesity and from a prior era is not available. It is likely that AR is now occurring earlier among children ‘at-risk’ for obesity. These observations are shown in Figure 1.
FIGURE 1. Adiposity Rebound
TEACHING CAPTION:
Note that for boys there is a 2.0 kg/m2 difference between the 5th and 50th percentiles (2.2 kg/m2 for girls) and a 4.2kg/m2 difference between the 50th and 95th percentiles (4.8 kg/ m2 for girls). Allison, et al, interpret these data to suggest that "… genetically susceptible individuals are being pushed to ever greater degrees of obesity by an "obesogenic" environment” that promotes obesity for susceptible individuals leaving the less susceptible unaffected.
A Case Study
Bernard - a member of a Caribbean immigrant family in Brooklyn.
(See appendix 1 below)
Bernard, age 4, is the younger of two sons of Mrs. “Bonneau,” a 28-year-old Haitian woman, who has lived in the United States for 7 years. Bernard and his older brother Andre, age 7, were both born in Brooklyn. Two years ago, as part of routine health care at the Brooklyn Pediatric Resource Center, Andre and his mother were found to have a positive tuberculin test. Bernard was negative. A follow-up chest X-ray showed Mrs. Bonneau to have active tuberculosis. She was treated with isoniazid and rifampin. Andre, whose chest X-ray was negative, was treated with isoniazid only.
Clinic personnel reassured Mrs. Bonneau that they were not worried about her condition, telling her that she had only a mild illness that is easily treated. But she was not reassured. All she was able to focus on was that "Andre is too skinny; he does not eat." This is thought, that overweight is healthy and being skinny is not, is still commonly held among Central and Eastern European immigrants who came to the United States in large numbers at the turn of the 20th century. Thus, for a child to be too skinny provides a rationale for Mrs. Bonneau to attempt to overfeed her children.
In fact, Andre is a lean child, whereas Bernard has the body shape preferred almost universally by the Caribbean immigrant families, (i.e., slightly overweight) [The complete case study can be found in Appendix #1 of this module.]
Growth measurements taken for Andre and Bernard are shown in Figure 2
TEACHING CAPTION:
Note that Andre has not yet reached his Adiposity Rebound while Bernard’s BMI began its upturn at 5 years of age. From Greenwood MRC, et al.(1993) Obesity in disadvantaged children. (in) Karp RJ (ed) Malnourished children in the United States: caught in the cycle of poverty. Springer publishing, NY. With permission.
Q1. Tracking the BMI might show an early rise followed by a decrease. Why is this?
A1. The usual tracking for weight gain relative to length or height would be a gain for the first six or seven months of age followed by a drop in the BMI. The early weight gain is certainly necessary as there is a need for fatty acids, hormones, and neuropeptides in the development of neural tissues. Caloric deprivation from inadequate intake, diarrheal disease, or hypermetabolic states is associated with profound neurodevelopmental delay. Neural tissues continue to be produced through the first two years of life though some evidence exists for prolonged development. Though we have no evidence of “why” this occurs, the survival benefit of early rise in BMI seems obvious.
Q2. Do all populations show a rise, then a fall, then a rise, or “AR?”
A2. Studies of AR in developing countries among children experiencing protein energy malnutrition show a different pattern of growth than children in nutritionally well off places. As shown by Bhargava and colleagues in south Asian children prone to malnutrition, the BMI rises continually through childhood crossing percentile curves as the children age without an AR. Recently, Barker showed a similar growth pattern in the childhood of adults in Finland who have developed diabetes mellitus. They show a rise in BMI of greater than one SD after they were two years of age.
Q3. What is the relation between early AR and metabolic syndrome?
A3. Children in developing countries where undernutrition in early childhood is endemic may not show an Adiposity Rebound, having missed the first phase of fat accumulation. Simply stated, a rise in BMI from 2 to 6 years of age increases the risk for metabolic syndrome with or without a true rebound.
Q4. How might these findings affect care for Anna?
A4. This is an opportunity for resident role-play. A full case study for Anna is presented as an appendix to the module
TABLE 1. Guidance to Prevent an Early Adiposity Rebound
What might be done in the pre-school?
1. Encourage wise choice of meals and snacks
2. Limit TV and other watching time
3. Develop sustainable activities – non competitive ones
What might be done at home?
1. Provide guidance on healthful foods
2. Make nutritious food available
3. Assure the family that Andre is well nourished
What may be done in the community?
1. Create consortiums of community-based organizations,
2. Form focus groups,
3. Develop programs unique to targeted communities,
4. Prepare material that promotes use of new foods,
5. Hold cooking classes, and
6. Evaluate the effectiveness of their intervention. All of these can be a
part of a Medical Home that addresses the health needs of the
community it serves.
[This table is from Karp RJ, Cheng C, Meyers AF. The appearance of discretionary income: Influence on the Prevalence of Under and Overnutrition. International Journal of Health Inequities http://www.equityhealthj.com/content/4/1/10]
Q5. What is the relation between an early AR and the onset of obesity?
A5. Simply stated, an early AR increases the risk for obesity later in life, though other factors are likely to affect this, such as, obesity in one or both biologic parents.
Q6. What is the relation between early AR and obesity?
A6. This may be a “which comes first? – the chicken or the egg?”. Williams and Dickson suggest that “timing of the adiposity rebound is an indicator of physical maturity rather then obesity.” Certainly, the secular trend in menarche from late teens suggests that the early accumulation of fat influences endocrine development leading to early menarche.
Q7. What relation is there between AR and menarche?
A7. This also may be a “which comes first? – the chicken or the egg?” issue. Williams and Dickson suggest that “timing of the adiposity rebound is an indicator of physical maturity rather then obesity.” Certainly, the secular trend in menarche from late teens suggests that the early accumulation of fat influences endocrine development leading to early menarche.
Appendix 1
This case study was prepared by Robert Karp and originally published in “Greenwood MRC, Johnson P, Karp R, M.D., Wolman PG. (Chapter 12) Obesity among disadvantaged children (in) Karp, RJ. (Ed) Malnourished Children in the United States: Caught in the Cycle of Poverty. Springer Publishing Co., New York. 1993
Bernard (a member of a Caribbean immigrant family in Brooklyn)
Bernard, age 3, is the youngest of two sons of Mrs. Bonneau, a 28-year-old Haitian woman, who has lived in the United States for 7 years. Bernard and his older brother Andre, age 6, were both born in Brooklyn. Two years ago, as part of routine health care at the Brooklyn Pediatric Resource Center, Andre and his mother were found to have a positive tuberculin test. Bernard was negative. A follow-up chest X-ray showed Mrs. Bonneau to have active tuberculosis. She was treated with isoniazid and rifampin. Andre, whose chest X-ray was negative, was treated with isoniazid only.
Clinic personnel reassured Mrs. Bonneau that they were not worried about her condition, telling her that she had only a mild illness that is easily treated. But she was not reassured. All she was able to focus on was that "Andre is too skinny; he does not eat."
This attitude that overweight is healthy and being skinny is not was one that was common among Central and Eastern European immigrants who came to the United States in large numbers at the turn of the last century. At that time, tuberculosis was the leading cause of death in Europe and in the United States. The disease was associated with wasting, but even Sir Willam Osler, the leading physician in the English-speaking world at that time, was uncertain as to whether the wasting was a cause or consequence of the disease. In his 1889 edition of The Principles and Practice of Medicine, Osler gives Hippocrates's description of the "phthitic habitus" of partial emaciation. This appearance was recognized as "too skinny" by Central and Eastern European immigrant grandmothers. Today, in the world's poorest nations, as many as 5 million children per year die in a context of undernutrition. These children are susceptible to chronic infection with gastroenteritis often being the final event before death (see Rabinowitz' comments in Malnourished Children in the United States). Thus, for a child to be too skinny provides a rationale for Mrs. Bonneau to attempt to overfeed her children.
In fact, Andre is a lean child, whereas Bernard has the body shape preferred almost universally by the Caribbean immigrant families, (i.e., slightly overweight) (see Figure above).
Based on comments by Mrs. Bonneau and other Haitian mothers, one could conclude that all Haitian children stop eating when they reach about 1 year of age. The natural diminution in appetite that does occur in all babies nearing their first birthday seems to create panic in these families. "My baby doesn't eat," is the invariable concern. Thus, these immigrant mothers work to get their children to eat and are rewarded by their culture if they are successful as evidenced by the production of slightly to moderately overweight children. This practice contributes to the higher prevalence of obesity in first- and second-generation immigrants with all of the associated consequences. The task of the clinic professional staff is to encourage these mothers to limit the weight gain of their children, a concept difficult for these mothers to accept, especially if the staff members who are advising them are themselves "too skinny."
The best hope for influencing these family patterns is that the educational efforts of health professionals will take effect in the next generation when these parents, as grandparents, repeat the advice that they were given. It is clear that very special efforts are needed to prevent obesity in the generation of children who arrive with newly immigrant parents from developing countries.
ANNOTATED ANSWERS
A1. The answer is False. The curves show a distinct discipline in deviation from the mean for the lower percentiles -- those below 50%. Above mean levels splay out widely so as to produce a non-Gaussian distribution for the population as a whole.
A2. The answer is B. That is very little change occurs between one and four years of age. The three phases of accumulation are in early infancy, during the period of "Adiposity" or "BMI" Rebound from 4 to 7 years of age, and in adolescence.
A3. The answer is False. Children living in underdeveloped countries where protein energy malnutrition is common are likely to create body fat and increase their BMI in a linear fashion. These children do not experience and Adiposity Rebound. Dietz's admonition that the Adiposity Rebound would be better termed a BMI rebound comes to mind here. We do not know what is being laid shown in the various circumstances throughout the world.
A4. The answer, at least for the time being, is A. An early AR is best associated with later obesity. The other factors may be also. Some concern has been raised that early weight gain is a predictor, but these concerns are for the period from birth to one year of age
