A study has found that even when eating the same food, blood sugar responses can differ depending on whether a person eats alone or with someone close.

On Oct. 1 local time, online media outlet Gigazine reported that a research team involving Israel's Hebrew University conducted experiments after concluding that social proximity, as well as what people eat, could affect blood sugar regulation.

The team had 108 participants eat 108 grams of white bread and tracked blood sugar changes for 2 hours. In one condition, participants ate the bread alone. In the other, they ate with someone with whom they had a close relationship. The type and amount of bread were kept the same.

The results were clear. Participants had smaller surges in blood sugar when eating with someone than when eating alone, and their blood sugar returned to baseline faster. Shahar Achir (샤하르 아치르), a professor of psychology at Hebrew University and a co-author of the paper, said blood sugar regulation depends not only on what people eat but also on whom they eat with.

The team found a similar trend both when comparing the same participants across the two conditions and when comparing different groups of participants. The area under the blood sugar rise was also smaller in the shared-meal condition. This suggests a dining companion may be directly involved in metabolic responses, rather than being a simple surrounding factor.

The study was not limited to blood sugar. The team also examined temperature responses when exposed to cold and sympathetic nervous system responses under stress. Body temperature drops were smaller and recovery was faster when participants were with someone close than when they were alone. Sympathetic nervous system activity after stress was also better suppressed. Participants did not touch or make skin contact with each other, and the differences appeared simply from being close together.

The team explained that while previous research mainly focused on the negative consequences of social isolation, this study showed social proximity offers direct, quantifiable benefits in blood sugar metabolism. A 2022 study had also presented findings that loneliness could double the risk of developing type 2 diabetes.

The researchers called the phenomenon a "socio-physiological function". It is the concept that the human body is not a system that maintains homeostasis completely independently, but performs self-regulation more efficiently when a social partner is nearby. Achir said the body has been viewed as an independent system that regulates itself, but these results show human physiological function is inherently social.

He also stressed that forming close relationships reduces the energy the body uses for self-regulation, and that being together itself has direct metabolic benefits. He added that the human body functions better when people are together.

The findings show that blood sugar management may not be explained only by the type and amount of food consumed. In particular, by confirming in figures how dining environments and social relationships affect actual physiological responses, the results could influence how health research addresses social factors.