Poultry meat and eggs are major sources of nutrients in human alimentation. The long production career of layers expose them to numerous stressors. Understanding the adaptive mechanisms is crucial to select robust animals and meet the needs of a growing human population. In this context, we compared the effects of a 15%-energy-reduced diet (LE) vs. a commercial diet (CT) in two feed-efficiency-diverging chicken lines. We first studied the effects of the LE on performances (egg mass, feed intake [FI], body weight) and body energy reserves, before investigating the molecular mechanisms at work by studying the adipose tissue, blood, hypothalamus and liver transcriptomes. The absence of differences in egg production between diets, combined to the increase in feed intake and the decrease in body weight in LE suggest an adaptation to the diet through an increase in energy input and a mobilization of body energy reserves. The birds reacted similarly to the diet in both lines, as shown by the absence of significant line×diet interactions. At the transcriptomic level, no interactions were detected. The increase in FI did not affect the liver, neither did the mobilization of body reserves for the adipose tissue. In blood, the differentially expressed genes were related to amino-acids, monosaccharides and steroid metabolisms. In the hypothalamus, the fatty acids metabolism and endocannabinoid signaling pathways were affected. We propose a mechanism involving endocannabinoids that could explain the increase in FI and therefore part of the adaptation to the low-energy diet. Work funded by ANR-13-ADAP-0014 and H2020-Feed-a-Gene projects.