In 1973, Hilde Bruch observed that obese children tended to belong to families characterised by a domineering, overprotective mother, a weak father, and a lack of responsiveness, warmth, and support towards the obese child.1 Later, studies also suggested that childhood obesity may be associated with some specific family characteristics, such as family cohesion, conflict, disorganisation, a lack of interest in social and cultural activities,2,3 and parental neglect.4 Other studies, however, have failed to support the hypothesis that obese children come from families displaying such dysfunctional traits.5,6 Thus, no clear pattern of family dynamics has consistently been associated with obesity.
The role of the family has implications for the treatment of obese children — family-based treatment programs for obese children are based on the theory that parenting style, family functioning, and the home environment are key factors.7-9 There is evidence of the long-term effectiveness of this approach.7
We investigated cross-sectional data from the Childhood Growth and Development (GAD) Study, a prospective, enriched cohort study being conducted in Western Australia. The GAD Study aims to identify the origins and consequences of the development and persistence of childhood obesity by studying healthy weight, overweight and obese children. The children are followed up twice a year for at least 3 years. One parent of each child is also taking part in the study. Families recruited during the first 2 years (January 2004 – December 2005) of the GAD Study provided the data for our analyses.
Participants for the GAD Study were recruited in two ways (Box 1).
A non-treatment-seeking sample of overweight and obese children was recruited from eight randomly selected primary schools in the Perth metropolitan area. All children at these schools took home an information sheet inviting them to be weighed and measured at school. All children with parental consent (n = 1080; 54%) who were present at the schools during the site visit were weighed in light clothing and without shoes with regularly calibrated digital medical scales (Tanita, Chicago, Ill, USA), and had their height measured with a regularly calibrated portable Harpenden stadiometer (Holtain Ltd, Crymych, UK) using the stretch technique (to the nearest millimetre). All measures were assessed twice, with the mean score recorded. Body mass index (BMI = weight [kg]/height [m]2) was calculated for each child. Children were classified as healthy weight, overweight or obese using Cole and colleagues’ age- and sex-specific overweight and obese BMI cut-offs for children.10 All children classified as overweight or obese (n = 181) were invited to participate in the prospective phase of the GAD Study (regardless of whether they were siblings of others in that group), and 127 (70%) agreed to participate; 123 of these attended the assessment interview.
Participating children and their mothers attended separate assessment interviews.
All children and their mothers were (re)weighed and (re)measured. Age- and sex-specific BMI z scores were calculated for the children using the United States Centers for Disease Control and Prevention 2000 reference data.11 Child BMI z scores were used in all analyses.
The family’s socioeconomic status was measured by maternal education level and total family income. Codes from the Socio-Economic Indexes for Areas (SEIFA), which includes an Index of Advantage/Disadvantage,12 were also obtained, based on residential address.
The number of children in the family, the number of residing parents, and parental marital status were recorded.
Maternal responses on a range of scales were used to assess family functioning, parenting style and maternal psychopathology. All scales have been shown to have good validity.
Depression Anxiety Stress Scales (DASS): The DASS is a set of three self-report scales designed to measure depression (dysphoria, hopelessness, devaluation of life, self-deprecation, lack of interest/involvement, anhedonia, and inertia), anxiety (autonomic arousal, skeletal muscle effects, situational anxiety, and subjective experience of anxious affect) and stress (difficulty relaxing, nervous arousal, and being easily upset/agitated, irritable/overreactive and impatient).13 Mothers rated the extent to which they had experienced each state over the previous week.
McMaster Family Assessment Device (FAD): The General Functioning Scale (12 items) of the FAD14 was administered to all mothers. This subscale assesses the overall health/pathology of the family. Mothers rated their agreement or disagreement with how well items described their family (eg, “We don’t get along well together”).
Parenting Scale: The 30-item Parenting Scale is designed to measure dysfunctional discipline practices.15 Paired extremes of discipline strategies form the anchors for a seven-point scale (eg, “When my child misbehaves, I raise my voice or yell” versus “When my child misbehaves, I speak to my child calmly”).
Life events scale: Mothers assessed recent negative life events using the List of Threatening Experiences,16 which includes 12 categories of negative life events (eg, illness, death of a close friend or relative, unemployment).
Rosenberg Self-Esteem Scale: This brief unidimensional measure of global self-esteem consists of 10 statements related to overall feelings of self-worth or acceptance.17 Items are summed to derive an overall score ranging between 10 and 40, with higher scores indicating higher maternal self-esteem.
The data were analysed using univariate and multivariate linear regression models incorporating a random intercept for within-family clustering. A series of univariate models were used to examine the relationships between child BMI z score, the primary independent variable, and each predictor variable. Age group and sex were considered as possible confounders.
All data analyses were performed using SPSS, version 12.0 (SPSS Inc, Chicago, Ill, USA).
There were 329 children (mean age, 9.51 years; SD, 1.84) and 265 mothers from 265 families; 192 children were classified as healthy weight, 97 overweight, and 40 obese.
In univariate models, increasing child BMI z score was found to be significantly associated with higher maternal BMI, an increasing likelihood of belonging to a single-parent family, fewer people living in the home, increasing social disadvantage (all P < 0.01), lower annual family income and fewer years of maternal education (both P < 0.05) (Box 2).
In a multivariate model, maternal BMI and family structure (single- or two-parent family) were the only factors significantly associated with child BMI z score (P < 0.01 and P < 0.05, respectively) (Box 2). There were no significant main or interaction effects of age group or sex.
Box 3 shows the results stratified by treatment-seeking (n = 23) and non-treatment-seeking (n = 114) overweight and obese children, both before and after adjusting for child BMI z score. Compared with mothers of non-treatment-seeking children, mothers of treatment-seeking children had significantly higher BMIs and reported significantly lower annual family incomes. Families of treatment-seeking children were more socially disadvantaged, according to the SEIFA index. However, after controlling for child BMI z score, these differences disappeared. There was also a trend for mothers of the treatment-seeking children to report higher levels of depression than mothers of the non-treatment-seeking children. This difference remained after adjusting for child BMI z score.
Using a range of well known and replicable measures of specific maternal and family characteristics, we found that having an overweight mother and coming from a single-parent (single-mother) family increased the likelihood of a child being overweight or obese. These findings are consistent with the results of a previous study conducted with a random sample of 1581 Australian school children aged 7–15 years,18 which found that having parents, especially mothers, who were overweight increased the risk of children being overweight.
However, some early research suggested that obese children tend to come from dysfunctional families,2,3 where “dysfunctional” described traits such as family conflict, disorganisation and parental neglect.
The discrepancy between the earlier studies and more recent studies of family functioning in relation to childhood obesity may reflect a temporal change. In developed countries, the prevalence of obesity among young people has increased dramatically over the past 10 years.19 Twenty to 30 years ago, when childhood obesity was significantly less prevalent, it may have been that obese children did come from relatively unsupportive family environments. Now that childhood obesity is more widespread, the problem is not confined to families with these problems.
Limitations of our study include its cross-sectional nature and omission of some aspects of family functioning, such as family communication patterns or the child’s perceived level of parental support. We are also unable to comment on the relationship between family functioning and obesity in single-father families, as there were too few of these for statistical analysis. In addition, it is important to acknowledge the possibility of a non-response bias. Families experiencing high levels of stress, maternal psychopathology or poor general functioning may have been less likely to participate in the study, thereby restricting the range of values on our measure of family functioning. However, our distribution of FAD scores suggested that the range of values was comparable to that reported in previous studies.20
2 Predicted effects of family and maternal factors on child body mass index (BMI) z scores
Family structure: single-parent family (v two-parent family) |
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SEIFA = Socio-Economic Indexes for Areas.12 DASS = Depression Anxiety Stress Scales. FAD = Family Assessment Device. | |||||||||||||||
3 Comparison of treatment-seeking and non-treatment-seeking overweight and obese children by family and maternal factors
Values are mean ± SD, unless otherwise indicated. BMI = Body mass index. SEIFA = Socio-Economic Indexes for Areas.12 DASS = Depression Anxiety Stress Scales. FAD = Family Assessment Device. | |||||||||||||||
Abstract
Objective: To investigate the relationship between a child’s weight and a broad range of family and maternal factors.
Design, setting and participants: Cross-sectional data from a population-based prospective study, collected between January 2004 and December 2005, for 329 children aged 6–13 years (192 healthy weight, 97 overweight and 40 obese) and their mothers (n = 265) recruited from a paediatric hospital endocrinology department and eight randomly selected primary schools in Perth, Western Australia.
Main outcome measures: Height, weight and body mass index (BMI) of children and mothers; demographic information; maternal depression, anxiety, stress and self-esteem; general family functioning; parenting style; and negative life events.
Results: In a multilevel model, maternal BMI and family structure (single-parent v two-parent families) were the only significant predictors of child BMI z scores.
Conclusion: Childhood obesity is not associated with adverse maternal or family characteristics such as maternal depression, negative life events, poor general family functioning or ineffective parenting style. However, having an overweight mother and a single-parent (single-mother) family increases the likelihood of a child being overweight or obese.