TY - JOUR T1 - Long working hours and change in body weight: analysis of individual-participant data from 19 cohort studies JF - International Journal of Obesity Y1 - 2020 A1 - Virtanen, Marianna A1 - Markus Jokela A1 - Lallukka, Tea A1 - Magnusson Hanson, Linda A1 - Pentti, Jaana A1 - Solja T. Nyberg A1 - Alfredsson, Lars A1 - G David Batty A1 - Casini, Annalisa A1 - Clays, Els A1 - DeBacquer, Dirk A1 - Ervasti, Jenni A1 - Fransson, Eleonor A1 - Halonen, Jaana I. A1 - Head, Jenny A1 - Kittel, France A1 - Knutsson, Anders A1 - Leineweber, Constanze A1 - Nordin, Maria A1 - Oksanen, Tuula A1 - Pietiläinen, Olli A1 - Rahkonen, Ossi A1 - Salo, Paula A1 - Archana Singh-Manoux A1 - Stenholm, Sari A1 - Suominen, Sakari B. A1 - Theorell, Töres A1 - Vahtera, Jussi A1 - Westerholm, Peter A1 - Westerlund, Hugo A1 - Mika Kivimäki KW - Preventive medicine KW - Risk Factors AB - Objective To examine the relation between long working hours and change in body mass index (BMI). Methods We performed random effects meta-analyses using individual-participant data from 19 cohort studies from Europe, US and Australia (n = 122,078), with a mean of 4.4-year follow-up. Working hours were measured at baseline and categorised as part time (<35 h/week), standard weekly hours (35–40 h, reference), 41–48 h, 49–54 h and ≥55 h/week (long working hours). There were four outcomes at follow-up: (1) overweight/obesity (BMI ≥ 25 kg/m2) or (2) overweight (BMI 25–29.9 kg/m2) among participants without overweight/obesity at baseline; (3) obesity (BMI ≥ 30 kg/m2) among participants with overweight at baseline, and (4) weight loss among participants with obesity at baseline. Results Of the 61,143 participants without overweight/obesity at baseline, 20.2% had overweight/obesity at follow-up. Compared with standard weekly working hours, the age-, sex- and socioeconomic status-adjusted relative risk (RR) of overweight/obesity was 0.95 (95% CI 0.90–1.00) for part-time work, 1.07 (1.02–1.12) for 41–48 weekly working hours, 1.09 (1.03–1.16) for 49–54 h and 1.17 (1.08–1.27) for long working hours (P for trend <0.0001). The findings were similar after multivariable adjustment and in subgroup analyses. Long working hours were associated with an excess risk of shift from normal weight to overweight rather than from overweight to obesity. Long working hours were not associated with weight loss among participants with obesity. Conclusions This analysis of large individual-participant data suggests a small excess risk of overweight among the healthy-weight people who work long hours. VL - 44 SN - 1476-5497 JO - International Journal of Obesity ER -