In this study, subtyping of dietary behaviour in overweight or obese individuals identified three latent classes (healthy eaters, irregular unhealthy eaters, and emotional eaters). Moreover, we identified a significant association between emotional eating and a higher BMI, waist circumference, and body fat percentage. Importantly, emotional eaters also had a higher prevalence of metabolic syndrome.
Despite their different dietary profiles, subjects in classes 1 and 2 showed no significant differences in cardiometabolic risk factors except for GGT. This might reflect similar distributions of age, sex, and underlying disease. Irregular unhealthy eaters were more likely to have irregular meals, dine out, and consume alcohol (which might explain the increased GGT in this group). In contrast, classes 2 and 3 had similar dietary behaviour patterns, except for emotional eating, which might have contributed to their higher rates of binge eating, irregular meals, and frequent snacking, which in turn could lead a higher BMI and a higher likelihood of metabolic syndrome.
Emotional eating can be defined as eating in response to negative emotions or stress and is one of the many causes for weight gain or regaining weight after dieting.29 It is known that stress and negative emotions can lead to a higher intake of palatable energy-dense foods, such as chocolate, cakes, biscuits, pizzas, hamburgers, French fries, and sausages.30 In a study performed in the Netherlands, emotional eating was found to be a mediator between depression and 5-year weight gain in mothers.31 In that study, depressive symptoms were associated with higher rates of emotional eating, which resulted in an increase in BMI independent of depressive symptoms. Emotional eating is also closely associated with insufficient sleep and poor sleep quality.29 Insufficient sleep can cause more negative emotions and interferes with regulation of emotion through neurobiological, cognitive, and behavioural pathways. Therefore, identifying the subtype of obesity, such as emotional eating, can facilitate tailored treatment, such as training in emotional regulation skills or improving other lifestyle factors such as sleep.
The cross-sectional nature of this study meant that we could not detect a difference in the baseline cardiometabolic risk factors between subjects with healthy dietary behaviours and those with unhealthy behaviours (classes 1 and 2). However, it was worthwhile to subtype the group with irregular unhealthy dietary behaviour for the purposes of prediction and intervention. Several studies have suggested that an unhealthy dietary pattern can lead to increased weight, BMI, and waist circumference32,33 and that this group of patients might achieve greater weight loss if they receive more tailored interventions targeting multiple health behaviours rather than strategies that target a single behaviour.34
To our knowledge, this is the first study in Korea that has used LCA to classify dietary behaviour and explore its association with metabolic syndrome in overweight or obese adults. Dietary behaviours are highly inter-related, often concurrent, and affected by a complex interplay of multiple risk factors, including socioeconomic status and other health-related behaviours. LCA can address the complexity of dietary behaviour and capture meaningful key patterns.27
Logistic regression analysis of metabolic syndrome and LCA-derived emotional eating showed significant associations but not when irregular unhealthy eaters were compared with relatively healthy eaters, indicating that some components of dietary behaviour have a greater effect than others.
The findings of this study suggest a practical approach for identifying different phenotypes among individuals who are overweight or obese. Emotional eaters should be prioritised for emotional regulation and encouragement of emotional well-being. A recent review suggested that mindfulness and meditation have the potential to decrease emotional eating.35
According to the American Heart Association, the timing and frequency of meals is also important in the management of cardiometabolic risk factors.36 Regular meals with avoidance of late-night snacking can attenuate the risk of heart disease and diabetes mellitus. In this regard, identifying individuals with unhealthy dietary behaviours, such as irregular mealtimes or frequent snacking (class 2), and managing them with the focus on eating patterns might help achieve a healthy cardiometabolic profile as well as effective weight reduction.
This study has several limitations. First, it was not possible to use a validated dietary questionnaire because the study was based on a retrospective review of medical charts. Second, categorising the components of the dietary behaviour questionnaire into nine items could be considered subjective; however, we attempted to offset this problem by referencing a dietary pattern evaluation tool devised for Koreans.22 Third, the questionnaire used in the study was self-administered, which might have introduced a degree of reporting bias. Fourth, the study data were obtained from a single hospital weight management clinic and might not be generalisable to other populations. Dietary behaviours can be influenced by sex, age, and socioeconomic factors.37 Neither sex-specific nor age-specific LCA could be performed in this study because of the relatively small number of patients enrolled after exclusion of those with missing data.
Despite its drawbacks, this study shows that subtyping obesity-related dietary behaviours could be a guide to prioritising the components that should be put in place for tailored cognitive behavioural therapy. Further rigorous research is needed for these interventions to be effective in weight management.