Parent-Reported Personality and Weight Transitions across Adolescence

Abstract

Background: Adolescence is a critical transition point for body weight. Personality traits are associated consistently with weight and obesity risk in adulthood. We examined whether personality, particularly Conscientiousness (the tendency to be organized, disciplined, and responsible), is associated with weight outcomes between ages 13 and 17.

Methods: Data are drawn from the Growing Up in Ireland suites of studies. Parents rated their child's personality at age 13, and trained staff measured weight and height at ages 13 and 17 (N = 4962). Logistic regression was used to predict risk of incident obesity and obesity remission between ages 13 and 17.

Results: Among children who were not in the obesity category at age 13, higher Conscientiousness was associated with lower risk of moving into the obesity category by age 17, and, among children with obesity at age 13, Conscientiousness was associated with greater likelihood of moving to the nonobesity category by age 17. These associations were independent of sociodemographic characteristics, parent body mass index, and were similar across gender. The other five-factor model personality traits were unrelated to weight outcomes.

Conclusions: Conscientiousness is one trait psychological factor implicated in weight transitions across a critical period during adolescence.

Introduction

Adolescence is a critical transition point for obesity and a time of great weight fluctuation.¹ Many children with overweight as a child become leaner through adolescence, and the opposite is also true, with some children gaining excess weight through this transition.² Genetic,³ familial,⁴ and social⁵ factors certainly contribute to weight trajectories across childhood. Less is known about how stable psychological factors are associated with weight transitions during this time. The five-factor model (FFM) of personality⁶ operationalizes an individual's characteristic ways of thinking, feeling, and behaving along five broad dimensions: Emotional Stability (the tendency to be calm and resilient to stress), Extraversion (the tendency to be sociable and outgoing), Openness (the tendency to be creative and unconventional), Agreeableness (the tendency to be compassionate and trusting), and Conscientiousness (the tendency to be organized, disciplined, and responsible). These traits emerge early in life and are associated with critical health outcomes across the life span.⁷

Of the FFM traits, Conscientiousness has been the trait most consistently associated with healthier weight outcomes. In adulthood, conscientious individuals are leaner,⁸ have a lower risk of developing obesity,⁹ and tend to maintain a more stable weight across adulthood.¹⁰ There is growing evidence that this trait also contributes to weight gain in childhood. Conscientiousness measured around age four, for example, is associated with healthier weight trajectories across childhood.¹¹ There are also long-term weight outcomes associated with this trait: teacher-reported Conscientiousness in childhood is associated with healthier body mass index (BMI) 40 years later.¹² Less work, however, has addressed whether this trait is associated with risk of obesity and obesity remission in adolescence, a critical period for body weight.

There is less evidence for the relation between the other four FFM personality traits and weight outcomes. Although there is some evidence that Emotional Stability is associated with healthier weight gain in childhood¹¹ and lower risk of obesity in adulthood,¹⁰ not all find this association.⁹ Likewise, the relation between Extraversion and body weight is not consistent,¹³ and Extraversion tends to be unrelated to risk of developing obesity in adulthood.⁹ Openness and Agreeableness also tend to be unrelated to obesity risk.⁹

The present research addresses whether child personality at age 13, as rated by the parent or other primary caregiver, is associated with risk of obesity at age 17 among children without obesity at baseline and whether it is associated with healthier weight outcomes at age 17 among children with obesity at age 13. We hypothesize that higher Conscientiousness will be associated with lower risk of developing obesity between ages 13 and 17, and that it will also be associated with remission across this time period. Our focus is on Conscientiousness because of its consistent association with healthier weight outcomes in adulthood, but we also report the relations for Emotional Stability, Extraversion, Openness, and Agreeableness to advance knowledge on all FFM traits. In particular, although the other four FFM traits tend to be unrelated to weight outcomes in adulthood, much less is known about their weight correlates in adolescence. We thus include them for completeness and to add to the literature on the health correlates of all FFM traits in adolescence.

Methods

Participants and Procedure

Participants were drawn from the second and third waves of the child cohort of the Growing Up in Ireland (GUI) suite of studies (https://www.growingup.ie). Study children and their families were recruited into the child cohort when the study child was 9 years old. Study children were reassessed again at ages 13–14 in 2011–2012 and 17–18 in 2015–2016. Written signed informed consent was obtained from a parent or guardian, and written signed assent was obtained from the study child before data were collected. GUI is approved by the Research Ethics Committee at the Department of Children and Youth Affairs (for more details, see https://www.growingup.ie/pubs/BKMNEXT307.pdf). Primary caregivers (99.9% parents) first rated their child's personality at the second wave at ages 13–14; BMI derived from staff-assessed weight and height was available for every assessment. Participants were selected into the analytic sample if they had parent-rated personality, measured BMI at both wave 2 (baseline in this study because this wave was the first wave to have FFM personality data) and wave 3, and the relevant covariates (parent gender, age, and whether born in Ireland, household income, partner in household, and study child gender and age). A total of 4962 participants met these criteria.

Measures

Personality

Observer ratings of the child's personality were obtained from the child's parent. The parent completed the observer-rating version of the Ten-Item Personality Inventory (TIPI), a short but validated measure of the five traits.¹⁴ Parents rated two items that measured each of five personality traits (Conscientiousness, Emotional Stability, Extraversion, Openness, and Agreeableness) on a scale from 1 (strongly disagree) to 7 (strongly agree).

BMI categories

Trained staff obtained anthropometric measurements during the household visit. Children were asked to wear light clothing for the measurements. Weight was measured using SECA flat mechanic scales and recorded to the nearest 0.5 kg. Height was measured using a portable height stick and recorded to the nearest millimeter. The International Obesity Task Force (IOTF) BMI percentile cutoffs were used to categorize BMI percentiles into overweight, obesity, and nonoverweight.¹⁵

Covariates

Covariates included parent self-reported gender, age, and whether born outside of Ireland (yes/no), annual household income (scaled in deciles), partner in household (yes/no), and study child parent-reported gender and age at baseline. Additional analyses also included parent BMI (n = 4746 due to missing data). Parent BMI was derived as kg/m² from measured weight and height by trained staff.

Analytic Strategy

Multivariate analysis of variance (MANOVA) was used to examine cross-sectional mean-level differences in parent-rated personality traits across weight categories at baseline, controlling for the covariates. The overweight and obesity weight categories were compared against the nonoverweight category.

We did two longitudinal analyses. First, we selected participants who did not measure in the obesity weight category at baseline. We used logistic regression to predict risk of incident obesity at follow-up (nonobesity = 0, obesity = 1) from personality, controlling for the covariates. Second, we selected participants who measured in the obesity category at baseline and again used logistic regression to predict obesity status at follow-up, controlling for the covariates. As a sensitivity analysis, we examined whether personality was associated with how weight category changed among participants who measured in the overweight category at age 13 and who transitioned to obesity by age 17. We also reran the models including parent BMI as an additional covariate and tested whether gender moderated any of the associations.

Results

Descriptive statistics are shown in Table 1. Table 2 shows the results of the MANOVA. Adolescents with overweight and obesity were rated lower in Conscientiousness by their parents than their peers without overweight. Adolescents with obesity were also rated as less extraverted, and adolescents with overweight were rated as more agreeable.

Table 1.

Descriptive Statistics for Study Variables

Variable	Mean (SD) or % (n)
Sociodemographic characteristics
Parent gender (female)	97.7% (4848)
Parent age at baseline (years)	41.29 (3.63)
Parent born in Ireland (no)	15.3% (758)
Household income at baseline (deciles)	6.19 (2.82)
Partner in household at baseline (yes)	88.3% (4381)
Child gender (female)	50.5% (2504)
Child age at baseline (years)	13.00 (0.12)
Parent-reported child personality at baseline
Conscientiousness	4.38 (2.00)
Emotional Stability	4.44 (1.96)
Extraversion	4.06 (1.92)
Openness	4.74 (1.81)
Agreeableness	5.01 (1.93)
IOTF BMI categories at baseline
Nonoverweight	76.3% (3787)
Overweight	19.3% (956)
Obesity	4.4% (219)
IOTF BMI categories at follow-up
Nonoverweight	75.9 (3767)
Overweight	18.1% (897)
Obesity	6.0% (298)
Obesity remission	34.7% (76)
Change in overweight status across follow-up	10.7% (506)
To nonoverweight	26.9% (136)
To obesity	73.1% (370)
Parent BMI at baseline (n = 4746)	26.44 (4.86)

N = 4962.

BMI, body mass index; IOTF, International Obesity Task Force; SD, standard deviation.

Table 2.

Baseline Personality Differences by Baseline Body Mass Index Category

Personality traits	Baseline BMI category
	Nonoverweight	Overweight	Obesity
Conscientiousness	4.42 (0.03)	4.24 (0.06)*	4.28 (0.14)
Emotional Stability	4.46 (0.03)	4.41 (0.06)	4.27 (0.13)
Extraversion	4.07 (0.03)	4.07 (0.06)	3.80 (0.13)*
Openness	4.73 (0.03)	4.81 (0.06)	4.59 (0.12)
Agreeableness	4.98 (0.03)	5.14 (0.06)*	5.08 (0.13)

N = 4962.

^*p < 0.05 for difference with nonoverweight.

Table 3 shows the results of the logistic regressions. Among adolescents who did not measure in the obesity category at baseline (n = 4743), higher Conscientiousness was associated with an ∼12% lower risk of developing obesity over the 4-year follow-up (incident obesity n = 155). Likewise, among adolescents with obesity at baseline (n = 219), higher Conscientiousness was associated with an ∼20% lower risk of remaining in this category at the follow-up assessment (remission obesity n = 76). These associations were virtually identical when parent BMI was included in the model (OR = 0.87, 95% CI = 0.80–0.95, n = 4537 and OR = 0.82, 95% CI = 0.70–0.96, n = 209, respectively). Further, among children with overweight at baseline and who changed BMI category by follow-up (n = 506), Conscientiousness was associated with moving to the nonoverweight category (OR = 0.90, 95% CI = 0.81–0.99, p = 0.036). The associations were similar across gender (i.e., there was no moderation by gender), and the other four traits were unrelated to the weight outcomes.

Table 3.

Baseline Personality Predictors of Obesity Status at Follow-Up

Personality traits	BMI at follow-up
	Risk of obesitya	Risk of remaining in obesity categoryb
Conscientiousness	0.88 (0.82–0.96)**	0.83 (0.72–0.97)*
Emotional Stability	0.96 (0.89–1.04)	0.88 (0.75–1.03)
Extraversion	0.95 (0.88–1.04)	1.08 (0.92–1.27)
Openness	0.99 (0.91–1.08)	0.86 (0.73–1.01)
Agreeableness	0.97 (0.89–1.05)	0.88 (0.75–1.03)

Total N = 4962.

^aN = 4743, including n = 155 incident obesity.

^bN = 219, including n = 76 obesity remission at follow-up.

^*p < 0.05; ^**p < 0.01.

Discussion

Adolescents higher in Conscientiousness have healthier weight outcomes over a 4-year period. This finding supports our hypothesis, and is consistent with and extends what is known about Conscientiousness and body weight in adulthood: higher Conscientiousness is associated with lower BMI¹⁶ and is protective against obesity.⁹ The present research indicates that adolescent Conscientiousness is likewise protective across a critical transition point in the life span.

The healthier behavioral patterns associated with Conscientiousness in childhood may be protective against obesity. Parent-reported Conscientiousness, for example, is associated with eating more fruits and vegetables and fewer sugary drinks among school-aged children.¹⁷ School-aged children higher in Conscientiousness are also more likely to pay attention to satiety cues while eating and are less likely to engage in emotional eating.¹⁸ Adolescents higher in Conscientiousness are more athletic¹⁹ and engage in more regular physical activity.²⁰ Cross-sectional data indicate that school-aged children higher in Conscientiousness are less likely to measure in the overweight or obesity weight category than children who score lower on this trait.¹⁷ The long-term cumulative effect of this healthier behavior is lower risk of obesity 40 years later.²¹

Much of the previous work on personality and weight trajectories in childhood has focused on temperament-related traits in early childhood and among elementary school children. Children rated as more persistent, a trait related to Conscientiousness, by their parent at age 4, for example, have healthier weight gain over the next decade.¹¹ School-aged children rated as higher in self-control likewise have healthier weight gain over the transition to middle school.²² The present research extends this evidence to a shorter time scale over a critical transition point in adolescence.

This study also indicates that Conscientiousness is implicated in weight transitions among children with overweight and obesity. In particular, even among children with obesity, higher Conscientiousness at age 13 was associated with moving to a healthier weight by age 17. And, among children with overweight who changed weight status between 13 and 17, Conscientiousness was associated with healthier weight outcomes. This pattern suggests that Conscientiousness is relevant for weight outcomes across the full range of BMI.

In contrast to Conscientiousness, and as expected, the other four traits within the FFM of personality (Emotional Stability, Extraversion, Openness, and Agreeableness) were unrelated to changes in BMI categories across adolescence. Although there is some evidence that low Emotional Stability (also referred to as Neuroticism) is associated with greater risk of obesity in adulthood,¹⁰ not all find this relation.⁹ Interestingly, the analysis of mean differences across the BMI categories suggested that Emotional Stability was somewhat lower among participants who measured in the overweight and obese categories, but this difference was not significant.

There are clinical implications to this research. Measures of Conscientiousness, for example, are a low-cost screening tool that would help identify who is at risk of developing obesity across adolescence. It also suggests that the positive characteristics associated with Conscientiousness may be leveraged to improve weight outcomes among adolescents who measure in the overweight or obese categories early in adolescence. In addition, to the extent that personality is malleable,²³ trait Conscientiousness may be a target of intervention to improve weight outcomes. Finally, these findings suggest that of the five broad dimensions of trait psychological functioning, it is most important to pay attention to Conscientiousness (for either surveillance and/or intervention).

The present research had several strengths, including a large sample, observer-rated personality reported by the child's parent, and staff-assessed height and weight at two points in time, measured 4 years apart. There are also some limitations. The personality assessment, for example, was limited. Future research could use a more comprehensive measure. Self-reported personality was also not available. It would be worthwhile to compare the association of the child's self-reported Conscientiousness with parent-reported Conscientiousness on weight outcomes. In addition, the sample was derived entirely of participants who had grown up in Ireland. As such, the findings may be specific to this population. The pattern of associations, however, is consistent with the adult literature on personality and body weight that has found similar associations for Conscientiousness in American,¹⁰ British,²⁴ Italian,²⁵ Israeli,²⁶ and Australian²⁷ populations. As such, it is likely that the results would generalize beyond the specific population here, but future work needs to confirm it. Despite these limitations, the present research indicates that Conscientiousness, as reported by the parent at age 13, is associated with healthier weight outcomes across a critical transition point in adolescence.

Authors' Contribution

A.R.S. developed the study idea and analyzed the data. Y.S. and A.T. provided critical feedback. All authors were involved in writing the article and had final approval of the submitted and published versions.

Funding Information

The Growing Up in Ireland is funded by the Government of Ireland through the Office of the Minister for Children and Youth Affairs. We thank the Central Statistics Office (Ireland), the Department of Health and Children (Ireland), and the Economic and Social Research Institute (ESRI) (Ireland) for access to the data. This work was supported by the National Institute on Aging of the National Institutes of Health under Award Number R01AG053297.

Author Disclosure Statement

No competing financial interests exist.

The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.