The Association between Dietary Changes to Lose Weight and American Adults' Mental Health Status in the National Health and Nutrition Examination Survey

Background: Weight loss is associated with numerous physical health benefits, such as better cardiovascular health. However, past research has focused on how weight loss strategies affect the mental health of a general population—rather than those trying to lose weight—or has investigated diverse weight loss strategies. This paper, therefore, explored how dietary changes for weight loss are associated with mental health, specifically through several variables used in the Patient Health Questionnaire-9, which measures depression severity. We hypothesized that eating less and skipping meals will be associated with poorer mental health status, while eating fewer carbohydrates, eating less fat, and drinking more water will be associated with better mental health status. The dependent variables are questions from the Patient Health Questionnaire-9, such as ‘feeling bad about yourself,’ ‘feeling down, depressed, or hopeless,’ and ‘little interest in doing things,’ and ‘the days of during the past 30 days when mental health has not been good.’ The independent variables answered, ‘How did you try to lose weight?’

Methods: This study used nationally representative data from the 2005-2006 National Health and Nutrition Examination Survey. We employed univariate, bivariate, ordinal logistic, and negative binominal regression analyses on a sample of 3,975 American adults. Participants’ age, sex, race, educational level, and annual household income were treated as covariates.

Results: The main results showed that ‘skipped meals’ were positively associated with ‘feeling bad about yourself (OR = 1.659, p < 0.01),’ ‘feeling down, depressed, or hopeless (OR = 1.336, p < 0.05),’ and ‘little interest in doing things (OR = 1.517, p <0.01).’ ‘Ate fewer carbohydrates’ was negatively associated with the ‘little interest in doing things (OR = 0.634, p < 0.01).’

Conclusion/Implications: Differing dietary changes used for weight loss, particularly skipping meals and eating fewer carbohydrates, are associated with differences in mental health status. Skipping meals is known to be associated with negative physical health consequences, including a reduced metabolism that can even promote weight gain when an individual consumes their typical food portions. Thus, clinicians can emphasize how weight loss can be achieved through eating a healthy, balanced diet without skipping meals. Healthcare professionals providing weight loss guidance should be cognizant of patients’ baseline mental health and the potential for changes in mental health with different dietary strategies. Implementing interventions (e.g., stress management program)—as demonstrated by effectiveness in not only reducing weight or BMI but also decreasing depression and anxiety scores—can ensure that patients achieve their weight loss goals while safeguarding their mental health. Future research needs to employ a longitudinal approach to determine the evidence of a causal relationship between these and other dietary strategies and subsequent mental health outcomes. Overall, our results make clear that individuals seeking weight loss should receive support from healthcare professionals in determining the effective and positive weight loss strategies that would be most appropriate while supporting the maintenance of mental health.