A new study, published in the journal Gut Microbes, has for the first time shown how social connections influence human weight and eating behavior through an integrated biological pathway involving brain function, metabolism, and the hormone oxytocin (“the love hormone”). The study’s findings suggest that the quality of relationships may be just as important for physical health as traditional risk factors such as exercise and diet.
The study’s lead author, Dr. Arpana Church of UCLA Health, noted: “While the impact of social relationships on health has been known for years, the biological mechanisms of this connection have not been adequately explained until now.”
The study involved nearly 100 residents of Los Angeles. Scientists collected data on their marital status, Body Mass Index (BMI), age, sex, diet quality, and socioeconomic status. They also performed brain imaging (while showing images of food), analyzed stool samples to examine metabolites, and conducted blood plasma tests to measure oxytocin levels.
Church’s laboratory found:
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Strong Emotional Support = Lower BMI: Married individuals with strong emotional support had a lower Body Mass Index (BMI) and reported fewer food addiction behaviors than married participants with low emotional support.
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Enhanced Control: Brain imaging showed that married people with strong emotional support had enhanced activity in the dorsolateral prefrontal cortex. This is the part of the brain that manages cravings and appetite.
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Different Effect on Unmarried Individuals: Unmarried individuals, regardless of whether they had strong emotional support from others, did not show similar brain activity, which may be explained by the diversity and less consistency of their social networks.
The central finding of the study relates to oxytocin. Married participants with strong emotional support exhibited higher levels of oxytocin compared to unmarried individuals.
According to Dr. Church, oxytocin likely acts as a biological messenger, simultaneously strengthening the brain regions involved in self-control and promoting metabolic processes in the gut.
“Think of oxytocin as the conductor orchestrating a symphony between the brain and the gut,” Church stated. “It enhances the brain’s ability to resist food cravings while also promoting beneficial metabolic processes in the gut, both of which help maintain a healthy weight.”
Social support also led to significant changes in gut metabolism. Those with stronger support showed beneficial alterations in tryptophan metabolites. These are compounds produced by gut bacteria that regulate inflammation, immune function, energy balance, and brain health. They are also involved in the production of serotonin and other compounds that affect mood, social behavior, and metabolism.
The research challenges overly simplistic views on marriage and weight. “Marriage can be a good exercise in self-control,” Church said. “Sustaining a long-term partnership requires constant suppression of impulses and alignment with long-term goals, which may strengthen the brain circuits involved in managing eating behavior.”
The study’s results provide direction for the prevention and treatment of obesity, suggesting the integration of healthy social relationships alongside diet and exercise.
