"Overall, transitions into marriage were associated with weight gain, whereas transitions out of marriage were associated with weight loss."

http://www.ncbi.nlm.nih.gov/pubmed/23050125

J Obes. 2012;2012:294974. Epub 2012 Sep 20.

The Association between Marital Transitions, Body Mass Index, and Weight: A Review of the Literature.

Dinour L, Leung MM, Tripicchio G, Khan S, Yeh MC.

Source

Department of Public Health, The Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA.

Abstract

Objective. To examine the association between different marital transitions and changes in body mass index (BMI) and body weight. 

Methods. A systematic literature search was conducted for peer-reviewed articles published between January 1990 and December 2011. Longitudinal studies were included if they compared dependent variables, such as BMI or weight, before and after a change in marital status. 

Results. Twenty articles were included: 4 articles described only transitions into marriage and/or cohabitation, 2 articles described only transitions out of marriage and/or cohabitation, and 14 articles described both. Overall, transitions into marriage were associated with weight gain, whereas transitions out of marriage were associated with weight loss. No major differences were observed between genders or across specific marital transition states. 

Conclusions. Additional research is warranted to better understand this phenomenon and the impact of marital transitions on obesity and obesity-related behaviors. This paper highlights potential opportunities to incorporate programs, practices, and policies that aim to promote and support healthy weights and lifestyles upon entering or leaving a marriage or cohabiting relationship.