long-term effects of parent weight on child weight loss

BEHAVIOR THERAPY 18, 219-226, 1987

Long-Term Effects of Parent Weight on Child Weight Loss

LEONARD H. EPSTEIN

RENA R. WING

ALICE VALOSKI

WILLIAM GOODINO

University o f Pittsburgh School of Medicine

This study was designed to assess the effects of parent weight (two nonobese/at least one obese parent) and child self-management or parent management on weight change of obese children over 5 years of observation. No differential effects of the two treatments were shown, but parent weight was associated with outcome. We have previously shown obese children with nonobese parents demonstrate similar relative weight changes over the first 6 months of treatment, but, from months 6 to 12, children with nonobese parents maintained their losses, while children with obese parents began to return to baseline relative weights (Epstein, Wing, Koeske, & Valoski, 1986). The present report shows maintenance of relative weight differences due to parent weight after 5 years of observation.

Obese children are at a greater risk for becoming obese adults than nonobese children across a wide variety of ages (Abraham, Collins, & Nordsieck, 1971; Abraham & Nordsieck, 1960; Charney, Goodman, McBride, Lyon, & Pratt, 1976; Garn & LaVelle, 1985; Stark, Atkins, Wolff, & Douglas, 1981). One important risk factor related to the etiology of childhood obesity is parent weight (Garn & Clark, 1976). Child weight and parent weight may interact in determining the child risk of adult obesity, as overweight infants of obese parents are more likely to become obese adults than overweight infants of nonobese parents (Charney et al., 1976). The mechanisms for the increased risk in offspring of obese parents are not well understood, though Stunkard and colleagues have shown that genetic factors play a role in determining adult weight status using both twin (Stunkard, Foch, & Hrubec, 1986) and adoption (Stunkard, Sorensen, Hanis, Teasdale, Chakraborty, Schull, & Schulsinger,

This research was supported in part by Grants HD12520 and HD20829 from the National In- stitutes of Child Health and Human Development. Appreciation is expressed to the individuals who served as therapists in this study, to Randi Koeske, who was responsible for the initial data analysis, and to Sheila Nudelman, who assisted in the collection of the five-year follow-up data.

Requests for reprints should be directed to Leonard H. Epstein, Western Psychiatric Institute and Clinic, 3811 O'Hara St., Pittsburgh, PA 15213-2593.

219 0005-7894/87/0219-022651.00/0 Copyright 1987 by Association for Advancement of Behavior Therapy

All rights of reproduction in any form reserved.

220 EPSTEIN ETAL.

1986) methodologies. In addition to these genetic factors, environmental factors may play a role in determining obesity, or both genetic and environmental factors may interact (Epstein & Cluss, 1986).

In spite of the important role of parent weight in determining child weight status and the risk of obese children becoming obese adults, there has been little controlled research on the effects of parent weight on child weight control. Dietz (1983) reported that children with no obese parents lost weight at a greater rate than children with at least one obese parent. However, less than one-third of the children completed the eight-week treatment program, and the rate of weight loss was based only on the sessions attended. Israel, Sil- verman and Solotar (1986) found that the number of overweight parents did not influence the percentage of children who lost at least 3.5 lbs. over the first 7 weeks of treatment.

We have found that parent weight may influence weight loss, and this effect becomes apparent over longer measurement intervals than those previously reported. Epstein et al. (1986) provided a year-long treatment to obese children with two nonobese or at least one obese parent. Similar changes in relative weight were observed for the first 6 months of treatment. Children with nonobese parents maintained their losses in relative weight from 6 months to 1 year, while children with obese parents began to regain relative weight. Children in both groups showed a decrement in treatment effectiveness over time, and at the end of 3 years neither group had relative weights different from baseline. However, there were differences in child relative weights as a function of parent weight at both one (p < .05) and three (p < .10) years.

The present paper reports on the influence of parental weight on outcome at 5 years. Extended follow-up assessments are important since treatment results often change over time, and extended follow-up measurements are needed to assess the durability of treatment effects. Five-year follow-up assessments are considered an acceptable long-term standard in obesity research (Stunkard & Penick, 1979). This report represents the second cohort of obese children followed over 5 years. Our initial five-year report showed that children who were targeted and reinforced for weight loss along with their parents showed maintenance of treatment influenced changes in percent overweight, while children in a child alone target or control group returned to baseline percent overweight (Epstein, Wing, Koeske & Valoski, 1987).

METHOD Subjects

Participants included 41 families who met the following criteria: (a) children 8-12 years of age, (b) between 20 and 80% over their ideal weight, (c) having triceps skinfold values greater than the 85th percentile (Garn & Clark, 1976), and (d) with no psychiatric contact or learning disability were accepted into the study. The sample included 24 children with at least one obese parent (greater than 20% over ideal weight and triceps greater than the 85th percentile) and 17 children with both parents not currently obese. Children were ran- domly assigned to one of two treatment groups, parent control or child self- control, crossing parent weight with treatment condition.

PARENT WEIGHT AND CHILD WEIGHT LOSS 221

Both treatments involved eight weekly treatment meetings with ten monthly meetings in which parents and children were seen separately (Brownell, Kelman & Stunkard, 1983) over a one-year period. At baseline parents deposited $85 in a deposit contract to be returned for attendance at treatment and maintenance meetings. Children and obese parents were provided a 1200-kilocalorie diet (Epstein, Wing, Koeske, Ossip, & Beck, 1982). Nonobese parents were given the same exercise program as the obese participants, and were placed on a caloric level which would maintain their weight.

Child eating and exercise behaviors were regulated using a point economy in which children earned points backed up by activity and privilege reinforcers. In both groups determination of when goals were met and awarding of points was performed initially by therapists, with parents being trained to take over contingency control. In the Child Self-Control condition these skills were then faded to the children. Parents remained in control of the back-up reinforcers for both conditions.

Weight and height were measured for all the parents and children at 0, 2, 6, and 12 months, and for the majority of parents and children at 36 and 60 months. If the participants could not be measured, then parent reports of their own and their child's height and weight were used. These parent reports were adjusted for parent report bias using regressing equations developed on a sample of 194 children and parents who had both parent reports and measured heights and weights available (Epstein, Nudelman & Wing, 1987). At the five-year follow-up, child and adult participants independently completed a retrospective questionnaire that assessed the extent to which people maintained eating and exercise control techniques, ratings of the effectiveness of the techniques, and their participation in other weight control programs.

RESULTS Percent overweight (070) served as the main dependent measure, since it takes

into account changes in weight and height over time relative to the child's age and sex. Data were analyzed first by three factor repeated measures analysis of variance and analysis of covariance, with Parent Weight and treatment condition (Parent/Child Control) as the between factors, time (0, 6, 12, 36, 60 months) as the within factor, and baseline percent overweight as the covariate for the analysis of covariance, and then by two factor analysis of variance or covariance considering the parent weight and treatment conditions separately. Planned comparisons of means at each time point were performed using the estimate of the pooled standard error.

Five-year data was available for 33 families (20 obese, 13 nonobese), which is 87°70 of the families followed at three years, and 80°70 of the total sample. Five children were lost from the three- to the five-year follow-up, which did not greatly influence the initial values or the changes over time. 1

i The unadjusted baseline means for the sample available at 3 years and the present five year sample of obese children with obese parents were 45.0 and 43.1, respectively, while that for obese children with nonobese parents were 35.4 and 37.7. Though the differences in characteristics of the samples from 3 to 5 years were small, the baseline values of the two groups

222 EPSTEIN ET AL.

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F[~. 1. Percent overweight of obese children with obese and nonobese parents over 5 years with values adjusted for differences in initial percent overweight (X_+S.E.M.)

Analyses showed no effects for treatment group (parent/child control) or any interactions with parent weight at any time period. Changes for children in the parent managed or child self managed groups were not significantly different at 6 months (-17.4, -14.7), 1 year (-12.4, -11.7), 3 years ( -5 .7 , + 0.1), or 5 years ( -3 .6 , + 3.3), though the long-term results did favor parent managed treatment.

The effects of parent weight on child relative weight change are presented in Fig. 1 based on the adjusted means. Means were adjusted for a slight difference in initial percent overweight between parent weight groups, but the pat- tern of results using adjusted or unadjusted means were identical. Planned comparisons showed no differences in percent overweight at 6 months. At one year, children with nonobese parents were 10.1 lower in percentage overweight (p = .048) than children with obese parents, at three years 8.6 lower in percent overweight (p = .098), and at five years 10.7 lower in percent overweight (p = .044). The proportion of children who were nonobese at five years was greater for children with nonobese parents (4/13, 31°70) than for children with obese parents (3/20, 15°/0), though these differences were not significant [X~(1) = .42, p > .05].

became more similar. While significant differences in percent overweight at baseline (p = .04) were observed for the three year sample, in the present sample there were no significant baseline differences (p > .10). In the initial report at 3 years (Epstein et al., 1986), a Z-score analysis was used to control for mean and variance differences in the two samples. In the present report, this was not necessary due to the absence o f initial differences, though the analysis o f covariance controlled for the slight between group differences at baseline.

PARENT W E I G H T AND CHILD W E I G H T LOSS 223

Children of obese and nonobese parents did not differ in height at 0, 6, 12, 36 or 60 months (obese -- 60.1_+4.3, 61.1_+4.2, 62.1_+ 4.3, 65.7-+4.0, 66.4_+4.0; nonobese = 58.3_+4.1, 59.3_+4.2, 60.4_+4.3, 64.1-+3.6, 65.7_+4.4). Children of obese parents tended to be heavier than children of nonobese parents at baseline (137.6__.32.1 vs. 120.9_+21.7, p < .20) and 6 months (129.8-+33.3, 109.8-+19.8, p < .10). The weight differences between the two groups became larger over time, and were significantly different (p < .05) at 12 (142.2_+36.2, 117.0_+20.8), 36 (177.6_+33.2, 152.8_+33.0) and 60 months (190.5___39.0, 166.4_+28.1).

While obese parents had significantly greater percent overweight than the nonobese parents at baseline (33.1+_23.8 vs. 10.4_+11.1), changes for obese and nonobese parents from baseline to 6 ( - 10.4, - 7.5) and 12 months ( - 8.3, - 5.0) were similar. By 36 months, parents in both groups were at baseline (+ 1.42, 0.74). At 60 months, parents in both groups were equally above baseline relative weight (+ 5.0, + 5.7). The majority of parents in both groups maintained their relative obese/nonobese distinctions. However, two parents in each of the obese and nonobese groups showed enough weight change over the 5 years to change their relative obese/nonobese position.

No relationship between initial child percent overweight and relative weight change were observed from baseline to 6, 12, 26, or 60 months. Significant correlations between parent and child changes were observed at 6 months and 3 years (r = .49, .49, p < .01), but not at 1 or 5 years (r = .32, .28, p > .05).

Retrospective five-year questionnaire data were analyzed by 2 X 2 contingency tables analyzing responses of the children and parents separately in terms of obese or nonobese parents, child gain or loss, and parent versus self-control. Chi-Square values are reported using Yate's correction for small sample size. The only significant effects were that nonobese parents perceived their children to be more successful in making habit changes [X2(1) = 3.99, p = .04] and maintaining lasting change in these habits [X2(1) = 3.89, p = .046] than obese parents.

DISCUSSION The results show that obese children of one or more obese parents are

significantly more overweight than obese children of nonobese parents 5 years after beginning a family-based behavioral weight control program. This difference can be attributed to different rates of relative weight gain beginning 6 months after treatment began. Children of both obese and nonobese parents lost weight at a similar rate during the first 6 months of treatment. Thereafter, children with obese parents regained weight faster than children of nonobese parents. At 1 year, a significant weight difference was present, and from 1 to 5 years both groups continued to gain weight at similar rates so that at 5 years the weight differences between the two groups of children persisted. No effects of emphasizing parent control versus child self control were observed.

These results suggest that parent weight may influence long-term treatment outcome, as well as influencing the etiology of childhood obesity (Garn & Clark, 1976). However, in interpreting these results it should be kept in mind that the between group differences were due to children of nonobese parents being

224 E P S T E I N ET AL.

slightly below baseline ( - 5.3%) after 5 years, while children of obese parents were about equally above baseline (+ 4.4%). Neither group showed a significant treatment response in terms of being significantly below their pretreatment levels. While developmental data might suggest that obese children who remained untreated might have been heavier than the obese children with nonobese parents observed in the present study, it is possible that treatment ac- celerated the between group differences observed. Further research evaluating the long-term effects of parent weight on treatment outcome should consider including nontreated control groups.

Treatment methods in the initial report of five-year follow-up (Epstein et al., 1987) produced better long-term outcome than those used in the current study. In the previous study, obese children with obese parents were treated; thus it is not likely that differences in parental characteristics were responsible for the different treatment results. In addition, parents and children were treated together in both studies. However, there were differences between the treatments offered in the two studies that may have influenced the outcomes. In the previous study, the parent plus child group was educated using a personal- ized system of instruction with mastery criteria, while in the present study all participants in the program were provided new information at the same rate, independent of subject mastery. In addition, subjects in the previous study were reinforced by deposit rebate for weight loss and behavior change, while in the current study monetary rebate was contingent only on attendance. Ad- ditional long-term research is needed to evaluate the effectiveness of these different behavioral treatment components, and to assess whether more powerful treatments would result in larger long-term differences between obese children with obese or nonobese parents.

It would be of considerable interest to determine the mechanisms that may account for the differential treatment response of obese children with obese and nonobese parents, some of which were outlined by Epstein and Cluss (1986). First, there may be individual differences between obese children of obese and nonobese parents that could influence weight loss and maintenance, similar to the individual differences in resting metabolic rate, caloric intake, and activity patterns that may differentiate normal weight children of obese and nonobese parents (Griffiths & Payne, 1976). Second, offspring of obese and nonobese parents may show differential adherence to the program over time, as we have previously shown (Epstein et al., 1986), which could produce difference in weight. Finally, these individual differences and behavioral aspects of compliance could interact. Obese children of obese parents may lose less weight or have more trouble maintaining weight given the same effort as obese children of nonobese parents, which could cause them to get discouraged and adhere less in future weight loss efforts. It is interesting that while the parents differed in percent overweight, they did not show differences in weight loss that might suggest mechanisms responsible for change or maintenance of change, as modeling.

Developing a better understanding of mechanisms for change, as well as evaluating the effects of more powerful programs on offspring of obese and nonobese parents, will be important to better understand the role of parent

PARENT WEIGHT AND CHILD W E I G H T LOSS 225

weight in long-term weight control. However, parent weight is but one family variable that may exert independent or interactive effects on outcome. For ex- ample, family size (Epstein et al, 1986) and marital status (Dietz, 1983; Israel et al, 1986) have both been documented to influence short-term outcome. These types of variables may be important because they can reduce parental time in managing the eating and exercise behavior of an obese child (Epstein et al, 1986), which can directly affect long-term weight control.

REFERENCES Abraham, S., Collins, G., & Nordsieck, M. (1971). Relationship of childhood weight status to

morbidity in adults. Public Health Reports, 85, 273-284. Abraham, S., & Nordsieck, M. (1960). Relationship of excess weight in children and adults. Public

Health Reports, 75, 263-273. Brownell, K. D., Kelman, S. H., & Stunkard, A. J. (1983). Treatment of obese children with and

without their mothers: Changes in weight and blood pressure. Pediatrics, 71, 515-523. Charney, E., Goodman, H. C., McBride, M., Lyon, B., & Pratt, R. (1976). Childhood antecedents

of adult obesity. Do chubby infants become obese adults? New England Journal of Medi- cine, 295, 6-9.

Dietz, W. H. (1983). Family characteristics affect rates of weight loss in obese children. Nutrition Research, 3, 43-50.

Epstein, L. H., & Cluss, P. A. (1986). Behavioral genetics of childhood obesity. Behavior Therapy, 17, 324-334.

Epstein, L. H., Nudelman, S., & Wing, R. R. (1987). Long term effects of family-based treatment for obesity on nontreated family members. Behavior Therapy. 12, 147-152.

Epstein, L. H., Wing, R. R., Koeske, R., Andrasik, E, & Ossip, D. J. (1981). Child and parent weight loss in family-based behavioral modification programs. Journal of Consulting and Clinical Psychology, 49, 674-685.

Epstein, L. H., Wing, R. R., Koeske, R., Ossip, D. J., & Beck, S. (1982). A comparison of lifestyle change and programmed aerobic exercise on weight and fitness changes in obese children. Behavior Therapy, 13, 651-665.

Epstein, L. H., Wing, R. R., Koeske, R., & Valoski, A. (1986). Effects of parent weight on weight loss in obese children. Journal of Consulting and Clinical Psychology, 54, 400-401.

Epstein, L. H., Wing, R. R., Koeske, R., & Valoski, A. (1987). Long-term effects of family-based treatment of childhood obesity. Journal of Consulting and Clinical Psychology, 55, 91-95.

Garn, S. M., & Clark, D. C. (1976). Trends in fatness and the origins of obesity. Pediatrics, 57, 443-456.

Garn, S. M., & LaVelle, M. (1985). Two-decade follow-up of fatness in early childhood. American Journal of Diseases of Children, 139, 181-185.

Grifliths, M., & Payne, P. R. (1976). Energy expenditure in small children of obese and non-obese parents. Nature, 260, 698-700.

Israel, A. C., Silverman, W. K., Solotar, L. C. (1986). An investigation of family influences on initial weight status, attrition, and treatment outcome in a childhood obesity program. Be- havior Therapy, 17, 131-143.

Stark, O., Atkins, E., Wolff, O. H., & Douglas, J. W. B. (1981). Longitudinal study of obesity in the National Survey of Health and Development. British Medical Journal, 283, 13-17.

Stunkard, A. J., Foch, T. T., & Hrubec, Z. (1986). A twin study of human obesity. Journal of the American Medical Association, 256, 51-54.

Stunkard, A. J., & Penick, S. B. (1979). Behavior modification in the treatment of obesity: The problem of maintaining weight loss. Archives of General Psychiatry, 36, 801-806.

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Stunkard, A. J., Sorensen, T. I. A., Hanis, C., Teasdale, T. W., Chakraborty, R., Schull, W. J., & Schulsinger, E (1986). An adoption study of human obesity. New England Journal of Medicine, 314, 193-198.

RECEIVED: December 3, 1986 FINAL ACCEPTANCE: April 7, 1987

long-term effects of parent weight on child weight loss

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