The presence of a close person - a romantic partner or a caring adult - may help the body maintain internal balance with less effort. The work was published in the journal Science Advances.
Scientists conducted four experiments: a pilot one with infants and three laboratory ones with adults. In each, they measured how far a physiological indicator deviates from its baseline during a load and how quickly it returns to normal. These two parameters were combined into an overall score reflecting the body's total effort. Participants underwent the tests both alone and next to a close person.
In the first experiment, 108 people (54 couples) ate a portion of white bread containing 50 grams of carbohydrates, and glucose levels were tracked for two hours. When the partner was nearby, sugar spikes were smaller and the decline occurred faster. The total rise in glucose above normal was on average 14.55% lower in the presence of the partner than when alone. When comparing only the first sessions of different groups, the difference was 23.9%.
In the second experiment, 116 adults were in a cold room. The skin cooled less and returned to its baseline temperature faster when the partner was nearby. The total drop in temperature was 16.17% smaller between groups and 6.76% smaller within the same people, although the within-person difference passed only a one-sided statistical test.
The third experiment, involving 115 adults, assessed the response to stress: participants received two short weak electric shocks to the forearm. The presence of the partner reduced total sympathetic nervous system arousal - the branch of the nervous system responsible for the "fight or flight" response - by 5.98% when comparing groups. The difference within the same people was 1.89% and was not statistically significant.
When the researchers combined all adult observations, total physiological effort was 7.59% lower within a person and 12.07% lower between groups under social conditions. This effect persisted with adjustment for relationship satisfaction, body mass index, time of day and session order. However, individual reactions varied: in some participants, regulation in the presence of the partner was less effective.
In the pilot study with infants, the babies heard a sharp sound - once when the mother was nearby and could comfort them, and once when she could not be seen or heard. The total skin response to stress was 2.55% lower within the children when the mother was present (one-sided test) and 4.24% lower between the groups of first sessions.
The authors emphasize that these are short-term effects recorded within a single day. The study does not prove that such changes persist long-term or prevent chronic diseases, including type 2 diabetes. The adult sample was limited to healthy young people in stable heterosexual couples, so the results cannot be automatically transferred to other types of relationships or to people with metabolic disorders.
"It is too early to translate these findings into specific clinical recommendations," cautions the head of the work, Shir Atzil of the Hebrew University of Jerusalem. "We are not claiming that eating together with a close person cures diabetes or that patients should change their glucose monitoring."
Independent experts noted the methodological strength of the work: preregistration of the experiments, sufficiently large samples and testing of three physiological systems. However, because partners could freely talk and touch each other, it remains unclear which specific aspects of the interaction produce the effect. Further work should test whether these effects persist in the long term and whether they extend to people with metabolic diseases.