In a recent study published in the journal Nutrients, researchers evaluate the mediating effects of physical activity, body mass index (BMI), and diet quality on the link between feeling lonely and diabetes.
Study: The Association of Loneliness with Diabetes Is Mediated by Physical Activity and BMI but Not Diet Quality. Image Credit: asylsun / Shutterstock.com
Loneliness, a subjective emotional state, is associated with an increased risk of diabetes and cardiovascular disease. Some of the underlying mechanisms that contribute to this increased risk include depression, impaired cognitive performance, and nursing home admission.
Loneliness deteriorates health through various pathways, including diet quality, physical activity, alcoholic beverages, smoking, and sleep patterns. Psychological factors such as perceived stress and depression have inconsistent effects on this association, which may be affected by unhealthy dietary behaviors and obesity. Thus, additional research is needed to explore the mediating pathways between loneliness and obesity to support the development of effective health interventions.
About the study
In the present study, researchers investigate whether physical activity, BMI, and diet quality mediate the relationship between loneliness and diabetes among white and African-American adults between 36 and 77 years of age in the United States.
The study included 1,713 individuals who participated in follow-up visits of the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study between 2013 and 2017 and had complete information on explanatory, predictor, and outcome variables were included in the current study. The HANDLS trial was conducted in 2004 and included 3,720 individuals to evaluate the impact of socioeconomic factors on health discrepancies among white and African-American Baltimore residents.
Participants were classified as non-diabetic, pre-diabetic, or diabetic based on fasting blood glucose levels, medications, and self-reports. The three-item University of California Los Angeles (UCLA) scale measured loneliness based on a lack of companionship, feeling left out, and social isolation.
Healthy Eating Index (HEI) 2010 scores were based on participant responses from two 24-hour diet recalls obtained using the automated multiple-pass method (AMPM) by the United States Department of Agriculture (USDA) to assess diet quality.
All participants received food booklets and other aids to estimate portion size. Food items were coded using the USDA Food and Nutrient Database for Dietary Studies (FNDDS).
Physical activity was assessed using the Baecke questionnaire, and mediation analysis was performed using the Hayes PROCESS macro-model. Covariates included age, sex, race, education, household income, and alcohol intake.
The mean participant age was 57, 59% of whom were women, 39% were white, and 38% had below-poverty income. Within the study cohort, 16% and 24% were classified as pre-diabetic and diabetic, respectively. About 14% of participants often felt the absence of a companion; however, only 8% reported feelings of social isolation.
Among the participants, 24%, 26%, and 51% were normal-weight, overweight, and obese, respectively. Pre-diabetes and diabetes were more frequently reported among white and African-American individuals, respectively.
Whites were more likely to report feeling left out as compared to African-American adults. Feeling lonely showed significant but inverse correlations with diet quality and physical activity.
Through the PROCESS Macro Model, nine direct paths connecting loneliness to diabetes were established, in which loneliness affects diet quality, BMI, or physical activity and, as a result, contributes to diabetes risk.
The likelihood of poor diet quality increased with feeling lonely. Age, female sex, higher educational attainment, and income 125% above poverty levels were significantly related to better dietary quality. Comparatively, being younger, male, or having completed more years of education increased the likelihood of greater physical activity levels.
Physical activity was a predictive factor that significantly contributed to variations in BMI values. Higher BMI values were significantly associated with younger age, being female, having an income exceeding 125% poverty status, and consuming fewer alcoholic beverages.
High BMI values were found to significantly increase the risk of diabetes in a dose-dependent manner, with a greater increase in BMI leading to a higher risk of diabetes. Physical activity and BMI had a significant and indirect on the effect of loneliness on diabetes risk. Race nor poverty status significantly impacted the effect of loneliness on diabetes.
Feeling lonely had significant but inverse associations with physical exercise and dietary quality, which aligns with previous studies.
The development of mental health disorders like depression and loneliness is often multifaceted, as the chronic inflammation associated with various diseases, including diabetes, shares similar pathology with depression. Furthermore, poor mental health often leads to low-quality diets that are high in processed foods and low in fruit and vegetables, in addition to poor sleep habits and increased mental distress.
The complex interplay between lifestyle and genetic factors on loneliness and diabetes emphasizes the importance of developing targeted intervention programs that may improve both mental and physical health outcomes.
- Kuczmarski, M. F., Orsega-Smith, E., Evans, M.K., & Zonderman, A.B. (2023). The Association of Loneliness with Diabetes Is Mediated by Physical Activity and BMI but Not Diet Quality. Nutrients 15; 4923. doi:10.3390/nu15234923