Eating problems normally onset in adolescence, with a peak at about 15-16 years . Although a number of risk factors for eating disorders and eating problems have been identified [2–4], the earlier childhood precursors of adolescent eating problems are not well understood. Existing longitudinal studies on risk factors for eating problems have generally relied on relatively short time spans  and have reported that the best predictor of late adolescence eating problems was an already present eating problem score at age 12 . This shows the need for studies starting at an earlier age to obtain information about potential risk factors at an age where such eating problems are not yet firmly established. The aim of this study was therefore to identify early childhood predictors of eating problems in adolescence at age 16.
Problematic eating patterns in childhood may develop to more serious eating problems during adolescence and may therefore be of particular importance. However, so far, only a small number of prospective studies have assessed eating behavior in younger children (under the age of 10 years) and followed the respondents into adolescence. In one of these studies, Kotler, Cohen, Davies and collaborators  showed that negative affect at mealtimes, struggles with food, and eating conflicts in early childhood predicted eating problems in adolescence, whereas five other types of problematic eating behaviors – including picky eating – were not predictive. Moreover, no longitudinal association was reported between childhood picky eating and eating concerns at age 14 in another study conducted by Martin and collaborators . In yet another prospective study, however, it was shown that picky eating in young children was related to adolescent eating problems . Thus, even though some prospective studies indicate certain eating problems in early childhood to be related to adolescent eating problems, the studies do not provide firm conclusions concerning which problems are predictive. Particularly for picky eating, some studies show long-term associations with adolescence eating problems, whereas other do not.
There is an ongoing discussion whether adolescent eating problems best can be understood as eating concerns and dieting escalating into more serious eating problems, or whether eating problems rather is a way of handling earlier manifestations of emotional problems. According to the affect regulating model  people may binge eat in an effort to provide comfort and distraction from adverse emotions. Moreover, research has shown that negative affect has been found to be prospectively related to eating problems among 9-10 year olds [10, 11] as well as in adolescents [5, 12].
Starting the examination of risk factors in toddlerhood may entail some challenges concerning assessment of child problems, and child behavioral descriptions will often be limited to parent report. As such, early manifestations of negative affect may be observed by the mothers of the toddlers as difficult temperament. Childhood temperament in toddlerhood has previously been described an early sign of later negative affect or emotional problems . Relevant for the current study, one longitudinal study investigated the role of child temperament in the development of eating concerns in early adolescence  and found that a high level of negative affectivity in 3–4-year-old girls was associated with adolescent eating concerns. Moreover, difficult infant temperament has been concurrently associated with negative mealtimes and food refusal in young children . Feeding difficulties have also been found to be more prevalent in children who are described as less sociable, difficult or demanding, and parental reports of having a shy, emotional child have been related to children’s unwillingness to try new foods [14, 15]. Several longitudinal studies in adolescence [5–16] have identified negative emotionality and depressive mood as predictors of eating problems, suggesting that it would be useful to extend the search downwards in age in order to possibly identify at which age emotionality, other temperamental traits, and internalizing problems may first be identified as risk factors for eating problems.
Finally, it has been suggested that early eating problems may be part of a self-regulation cluster, encompassing, for instance, difficulties with sleep and emotion regulation, which again may serve as precursors of a number of different emotional problems . Childhood sleep problems are closely related to eating problems in early childhood . Thus, it is reasonable to believe that sleep problems early in life could be a precursor, or at least a correlate to later eating problems. We were therefore interested in studying the potential longitudinal link between sleep and eating concerns.
Overall, there is limited research on childhood predictors of adolescent eating problems, as research on early childhood risk factors has mainly relied on retrospective information from cross-sectional studies or on designs measuring outcomes before adolescent eating problems occur. In the present study we seek to build on the previous body of work by extending the investigation of possible precursors downward to early childhood, i.e., before school age. More specifically, we aimed to investigate prospective predictors of adolescent eating problems, including eating problems, temperament, internalizing problems, and sleep problems in preschool age. Based on existing research, we hypothesized that picky eating, sleep problems, temperamental shyness and emotionality assessed before 5 years would predict adolescent eating problems.