# Ability to predict irregular periods of food depriviation improves body-weight regulation and reduces weight gain in food-insecure starlings

## TL;DR

Starlings that could predict when food would be unavailable regulated their weight better and gained less weight compared to those with unpredictable food access.

## Contribution

The study shows that predictability of food deprivation leads to better body-weight regulation in starlings.

## Key findings

- Predictable food deprivation led to reduced food intake and less weight loss during deprivation.
- Birds with the strongest behavioral response to cues had the lowest body-weight variance.
- Unpredictable deprivation was associated with higher body weight over time.

## Abstract

Food insecurity is associated with higher body weight in humans and other species, but the causal effect of unpredictable food availability on weight gain is unknown. We measured food intake and weight in starlings (Sturnus vulgaris) exposed to repeated irregular periods of food deprivation. We manipulated the predictability of deprivation between subjects with a 1 h visual cue that either reliably preceded deprivation (Predictable group) or was uncorrelated with deprivation (Unpredictable group). During the cue, Predictable birds reduced their food intake and spent less time inactive, indicating that they had learnt the contingency. Despite these responses, they lost less weight during subsequent deprivation. They also ate less and gained less weight when food was returned. Birds with the largest behavioural response to the cue had the lowest overall variance in body weight. Consistent with the insurance hypothesis, food intake and body weight increased over time in both groups and body weight was higher in the Unpredictable group. Our results suggest that when food deprivation was predictable, birds were less reliant on stored fat and instead used conditioned hypometabolism to mitigate the effects of food deprivation. We discuss the implications of our findings for the differential health impacts of food insecurity and intermittent fasting.