Loneliness is associated with adverse health behaviour and obesity: a Danish population-based study of 122,258 individuals

Martin Mejlby Jensen; Karina Friis; Helle Terkildsen Maindal; Anne-Sofie Hargaard; Maria Gjaldbaek Knudsen; Marie Stjerne Grønkjaer; Mathias Lasgaard

doi:10.1186/s12889-025-21490-4

Loneliness is associated with adverse health behaviour and obesity: a Danish population-based study of 122,258 individuals

Martin Mejlby Jensen^*, Karina Friis, Helle Terkildsen Maindal, Anne-Sofie Hargaard, Maria Gjaldbaek Knudsen, Marie Stjerne Grønkjaer, Mathias Lasgaard

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

BACKGROUND: Loneliness is a public health concern associated with increased morbidity and mortality. Adverse health behaviours and a higher body mass index (BMI) have been proposed as key mechanisms influencing this association. The present study aims to examine the relationship between loneliness, adverse health behaviour and a higher BMI, including daily smoking, high alcohol consumption, physical inactivity, unhealthy dietary habits, and obesity in men and women and across different life stages.

METHODS: We conducted a cross-sectional study using data from the 2017 Danish National Health Survey (entitled "How are you?"). Loneliness was assessed using the Three-Item Loneliness Scale. Logistic regression models were employed to analyse the association between loneliness, health behaviour and obesity in a sample of 122,258 individuals (16 + years). The models were adjusted for sex, age, educational attainment, country of origin, and partnership status. Stratified analyses were conducted to investigate differences by sex and life stages.

RESULTS: Loneliness was associated with an increased risk of daily smoking (Adjusted odds ratio (AOR) = 1.30; 95% CI: 1.21-1.40), physical inactivity (AOR = 1.87; 95% CI: 1.75-1.99), unhealthy diet (AOR = 1.58; 95% CI: 1.47-1.70), and obesity (AOR = 1.60; 95% CI: 1.49-1.72). Conversely, loneliness was associated with a reduced risk of high alcohol consumption in men (AOR = 0.82; 95% CI: 0.74-0.0.91).

CONCLUSIONS: Our study provides evidence that loneliness is associated with adverse health behaviour and obesity in both men and women and across the lifespan. These findings suggest that health behaviours and obesity may influence the association between loneliness and poor health outcomes. Longitudinal studies are needed to clarify the causal relationships underlying these associations.

Original language	English
Article number	375
Journal	BMC Public Health
Volume	25
Issue	1
Number of pages	11
ISSN	1471-2458
DOIs	https://doi.org/10.1186/s12889-025-21490-4
Publication status	Published - Dec 2025

Keywords

Adolescent
Adult
Aged
Alcohol Drinking/epidemiology
Alcohol consumption
Body Mass Index
Cross-Sectional Studies
Denmark/epidemiology
Diet
Female
Health Behavior
Health Surveys
Humans
Loneliness
Loneliness/psychology
Male
Middle Aged
Obesity
Obesity/epidemiology
Physical activity
Smoking/epidemiology
Young Adult
Health behaviour
Smoking

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10.1186/s12889-025-21490-4

Cite this

@article{760ba6b5d6cc4aaa86ade779287cac01,

title = "Loneliness is associated with adverse health behaviour and obesity: a Danish population-based study of 122,258 individuals",

abstract = "BACKGROUND: Loneliness is a public health concern associated with increased morbidity and mortality. Adverse health behaviours and a higher body mass index (BMI) have been proposed as key mechanisms influencing this association. The present study aims to examine the relationship between loneliness, adverse health behaviour and a higher BMI, including daily smoking, high alcohol consumption, physical inactivity, unhealthy dietary habits, and obesity in men and women and across different life stages.METHODS: We conducted a cross-sectional study using data from the 2017 Danish National Health Survey (entitled {"}How are you?{"}). Loneliness was assessed using the Three-Item Loneliness Scale. Logistic regression models were employed to analyse the association between loneliness, health behaviour and obesity in a sample of 122,258 individuals (16 + years). The models were adjusted for sex, age, educational attainment, country of origin, and partnership status. Stratified analyses were conducted to investigate differences by sex and life stages.RESULTS: Loneliness was associated with an increased risk of daily smoking (Adjusted odds ratio (AOR) = 1.30; 95% CI: 1.21-1.40), physical inactivity (AOR = 1.87; 95% CI: 1.75-1.99), unhealthy diet (AOR = 1.58; 95% CI: 1.47-1.70), and obesity (AOR = 1.60; 95% CI: 1.49-1.72). Conversely, loneliness was associated with a reduced risk of high alcohol consumption in men (AOR = 0.82; 95% CI: 0.74-0.0.91).CONCLUSIONS: Our study provides evidence that loneliness is associated with adverse health behaviour and obesity in both men and women and across the lifespan. These findings suggest that health behaviours and obesity may influence the association between loneliness and poor health outcomes. Longitudinal studies are needed to clarify the causal relationships underlying these associations.",

keywords = "Adolescent, Adult, Aged, Alcohol Drinking/epidemiology, Alcohol consumption, Body Mass Index, Cross-Sectional Studies, Denmark/epidemiology, Diet, Female, Health Behavior, Health Surveys, Humans, Loneliness, Loneliness/psychology, Male, Middle Aged, Obesity, Obesity/epidemiology, Physical activity, Smoking/epidemiology, Young Adult, Health behaviour, Smoking",

author = "Jensen, {Martin Mejlby} and Karina Friis and Maindal, {Helle Terkildsen} and Anne-Sofie Hargaard and Knudsen, {Maria Gjaldbaek} and Gr{\o}nkjaer, {Marie Stjerne} and Mathias Lasgaard",

note = "{\textcopyright} 2025. The Author(s).",

year = "2025",

month = dec,

doi = "10.1186/s12889-025-21490-4",

language = "English",

volume = "25",

journal = "BMC Public Health",

issn = "1471-2458",

publisher = "BioMed Central",

number = "1",

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Loneliness is associated with adverse health behaviour and obesity: a Danish population-based study of 122,258 individuals. / Jensen, Martin Mejlby ; Friis, Karina ; Maindal, Helle Terkildsen et al.
In: BMC Public Health, Vol. 25, No. 1, 375, 12.2025.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Loneliness is associated with adverse health behaviour and obesity

T2 - a Danish population-based study of 122,258 individuals

AU - Jensen, Martin Mejlby

AU - Friis, Karina

AU - Maindal, Helle Terkildsen

AU - Hargaard, Anne-Sofie

AU - Knudsen, Maria Gjaldbaek

AU - Grønkjaer, Marie Stjerne

AU - Lasgaard, Mathias

PY - 2025/12

Y1 - 2025/12

N2 - BACKGROUND: Loneliness is a public health concern associated with increased morbidity and mortality. Adverse health behaviours and a higher body mass index (BMI) have been proposed as key mechanisms influencing this association. The present study aims to examine the relationship between loneliness, adverse health behaviour and a higher BMI, including daily smoking, high alcohol consumption, physical inactivity, unhealthy dietary habits, and obesity in men and women and across different life stages.METHODS: We conducted a cross-sectional study using data from the 2017 Danish National Health Survey (entitled "How are you?"). Loneliness was assessed using the Three-Item Loneliness Scale. Logistic regression models were employed to analyse the association between loneliness, health behaviour and obesity in a sample of 122,258 individuals (16 + years). The models were adjusted for sex, age, educational attainment, country of origin, and partnership status. Stratified analyses were conducted to investigate differences by sex and life stages.RESULTS: Loneliness was associated with an increased risk of daily smoking (Adjusted odds ratio (AOR) = 1.30; 95% CI: 1.21-1.40), physical inactivity (AOR = 1.87; 95% CI: 1.75-1.99), unhealthy diet (AOR = 1.58; 95% CI: 1.47-1.70), and obesity (AOR = 1.60; 95% CI: 1.49-1.72). Conversely, loneliness was associated with a reduced risk of high alcohol consumption in men (AOR = 0.82; 95% CI: 0.74-0.0.91).CONCLUSIONS: Our study provides evidence that loneliness is associated with adverse health behaviour and obesity in both men and women and across the lifespan. These findings suggest that health behaviours and obesity may influence the association between loneliness and poor health outcomes. Longitudinal studies are needed to clarify the causal relationships underlying these associations.

AB - BACKGROUND: Loneliness is a public health concern associated with increased morbidity and mortality. Adverse health behaviours and a higher body mass index (BMI) have been proposed as key mechanisms influencing this association. The present study aims to examine the relationship between loneliness, adverse health behaviour and a higher BMI, including daily smoking, high alcohol consumption, physical inactivity, unhealthy dietary habits, and obesity in men and women and across different life stages.METHODS: We conducted a cross-sectional study using data from the 2017 Danish National Health Survey (entitled "How are you?"). Loneliness was assessed using the Three-Item Loneliness Scale. Logistic regression models were employed to analyse the association between loneliness, health behaviour and obesity in a sample of 122,258 individuals (16 + years). The models were adjusted for sex, age, educational attainment, country of origin, and partnership status. Stratified analyses were conducted to investigate differences by sex and life stages.RESULTS: Loneliness was associated with an increased risk of daily smoking (Adjusted odds ratio (AOR) = 1.30; 95% CI: 1.21-1.40), physical inactivity (AOR = 1.87; 95% CI: 1.75-1.99), unhealthy diet (AOR = 1.58; 95% CI: 1.47-1.70), and obesity (AOR = 1.60; 95% CI: 1.49-1.72). Conversely, loneliness was associated with a reduced risk of high alcohol consumption in men (AOR = 0.82; 95% CI: 0.74-0.0.91).CONCLUSIONS: Our study provides evidence that loneliness is associated with adverse health behaviour and obesity in both men and women and across the lifespan. These findings suggest that health behaviours and obesity may influence the association between loneliness and poor health outcomes. Longitudinal studies are needed to clarify the causal relationships underlying these associations.

KW - Adolescent

KW - Adult

KW - Aged

KW - Alcohol Drinking/epidemiology

KW - Alcohol consumption

KW - Body Mass Index

KW - Cross-Sectional Studies

KW - Denmark/epidemiology

KW - Diet

KW - Female

KW - Health Behavior

KW - Health Surveys

KW - Humans

KW - Loneliness

KW - Loneliness/psychology

KW - Male

KW - Middle Aged

KW - Obesity

KW - Obesity/epidemiology

KW - Physical activity

KW - Smoking/epidemiology

KW - Young Adult

KW - Health behaviour

KW - Smoking

UR - http://www.scopus.com/inward/record.url?scp=85217357448&partnerID=8YFLogxK

U2 - 10.1186/s12889-025-21490-4

DO - 10.1186/s12889-025-21490-4

M3 - Journal article

C2 - 39881306

SN - 1471-2458

VL - 25

JO - BMC Public Health

JF - BMC Public Health

IS - 1

M1 - 375

ER -

Loneliness is associated with adverse health behaviour and obesity: a Danish population-based study of 122,258 individuals

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Keywords

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