Early life stress is associated with anxiety, increased stress responsivity and preference for "comfort foods" in adult female rats.

Early stress changes the balance between ordinary food and highly palatable food

Stress can affect both emotional behavior and eating, but those effects do not necessarily amount to a general increase in appetite. This study investigated how an adverse early environment shaped adult female rats’ stress responses and preference for highly palatable food.

Creating and following an early adversity. From days two to nine after birth, mothers and pups had either limited nesting material or standard conditions. In adulthood, the offspring were assessed in a test that measures hesitation to eat in an unfamiliar environment. Researchers also measured the hormonal response to an acute stressor and monitored feeding during thirty days of access to ordinary chow alone or a choice of chow and a palatable diet.

The animals responded differently to both stress and food. Rats exposed to early stress took longer to begin eating in the unfamiliar setting and ate less chow on returning home. They released more corticosterone in response to stress, although the upstream hormone ACTH did not show the same increase. Despite being lighter and eating less ordinary chow, they consumed more palatable food during prolonged access.

Repeated exposure also affected preference differently. Control animals given long-term access to the palatable diet later showed less preference for it than controls previously fed only chow. The early-stress group did not show this reduction. Their attraction to the palatable option remained relatively persistent.

The authors propose that such food may become part of a behavioral response to anxiety, sometimes described as comfort eating. The experiment supports a relationship between early adversity, altered stress responsiveness and selective food intake, but it does not directly demonstrate that eating the food relieved the animals’ anxiety or that relief caused the preference.

The study’s specific contribution is the combination: heightened stress responsiveness accompanied increased palatable-food intake without greater body weight or greater consumption of ordinary food.