ABSTRACT
Excess weight gained during the early years and, in particular, rapid weight gain in the first 2 years of life, are a major risk factors for adult obesity. The growing consensus is that childhood obesity develops from a complex interaction between genetic susceptibility and exposure to an 'obesogenic' environment. Behavioural susceptibility theory (BST) was developed to explain the nature of this gene-environment interaction, and why the 'obesogenic' environment does not affect all children equally. It hypothesizes that inherited variation in appetite, which is present from birth, determines why some infants and children overeat, and others do not, in response to environmental opportunity. That is, those who inherit genetic variants promoting an avid appetite are vulnerable to overeating and developing obesity, while those who are genetically predisposed to have a smaller appetite and lower interest in food are protected from obesity-or even at risk of being underweight. We review the breadth of research to-date that has contributed to the evidence base for BST, focusing on early life, and discuss implications and future directions for research and theory. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.
Subject(s)
Appetite , Pediatric Obesity , Child , Humans , Appetite/genetics , Genetic Predisposition to Disease , Feeding Behavior/physiology , Gene-Environment InteractionABSTRACT
BACKGROUND: Emotional over-eating (EOE) and emotional under-eating (EUE) are common behaviours that develop in early childhood and are hypothesised to play a role in weight status. Data from a British twin cohort demonstrated that environmental, rather than genetic, factors shape individual differences in both behaviours in early childhood. OBJECTIVE: The aim of this current study was to replicate this finding in a subsample (n = 398) of 4-year-old twins selected for high or low risk of obesity from another population-based cohort of British twins (the Twins Early Development Study). METHODS: Parental ratings of child EOE and EUE were analysed using genetic model fitting. RESULTS: Genetic influence was not significant, while shared environmental factors explained 71% (52-79%) of the variance in EOE and 77% (62-85%) in EUE. The two behaviours correlated positively (r = 0.53, 95% CI: 0.44, 0.61), and about two-thirds of the shared environmental factors influencing EOE and EUE were the same (rC = 0.67, 95% CI: 0.51, 0.85). CONCLUSIONS: Emotional eating in childhood is shaped by the home family environment; parents are therefore promising intervention targets.
Subject(s)
Feeding Behavior/psychology , Feeding and Eating Disorders/etiology , Pediatric Obesity/etiology , Body Weight , Child , Child, Preschool , Emotions , Environment , Feeding and Eating Disorders/psychology , Female , Humans , Male , Parents , Pediatric Obesity/psychology , Risk Factors , TwinsABSTRACT
BACKGROUND AND OBJECTIVES: Shorter sleep is associated with higher weight in children, but little is known about the mechanisms. The aim of this study was to test the hypothesis that shorter sleep was associated with higher energy intake in early childhood. METHODS: Participants were 1303 families from the Gemini twin birth cohort. Sleep duration was measured using the Brief Infant Sleep Questionnaire when the children were 16 months old. Total energy intake (kcal per day) and grams per day of fat, carbohydrate and protein were derived from 3-day diet diaries completed by parents when children were 21 months old. RESULTS: Shorter nighttime sleep was associated with higher total energy intake (P for linear trend=0.005). Children sleeping <10 h consumed around 50 kcal per day more than those sleeping 11-<12 h a night (the optimal sleep duration for children of this age). Differences in energy intake were maintained after adjustment for confounders. As a percentage of total energy intake, there were no significant differences in macronutrient intake by sleep duration. The association between sleep and weight was not significant at this age (P=0.13). CONCLUSIONS: This study provides the first evidence that shorter nighttime sleep duration has a linear association with higher energy intake early in life. That the effect is observed before emergence of associations between sleep and weight indicates that differences in energy intake may be a mechanism through which sleep influences weight gain.
Subject(s)
Energy Intake , Pediatric Obesity/etiology , Sleep , Body Mass Index , Body Weight , Child , Child, Preschool , Diet Records , Dietary Carbohydrates , Dietary Fats , Dietary Proteins , Female , Humans , Male , Pediatric Obesity/epidemiology , Pediatric Obesity/prevention & control , Socioeconomic Factors , Surveys and Questionnaires , United Kingdom/epidemiology , Weight GainABSTRACT
An individual's experience of flavours contributes to their unique pattern of food preferences. Exposure to a specific flavour can increase familiarity and result in greater acceptance of this flavour over time. This paper describes the earliest occurrences of flavour exposure; first in utero, via amniotic fluid, and later through breast or formula milk. Evidence suggests these early experiences impact on later food preferences, but the extent to which specific flavour compounds from the mother's diet are transmitted during these pre- and early post-natal periods may vary within and between individuals. In contrast with findings with toddlers and older children, infants accept new flavours rapidly, with relatively few exposures required. Early exposure to flavour variety may improve long term dietary outcomes, highlighting the need to promote a varied diet during pregnancy and lactation.
