Circadian feeding pattern in pregnant rats fed three levels of protein.

Food intake was measured at regular intervals over 24 h in pregnant and non-pregnant female rats fed diets of different protein content: 10, 16 and 32%. During the course of pregnancy, a first period of hyperphagia was observed (days 2-12) irrespective of the composition of the diet. A second phase of hyperphagia occurred later (days 16-19) which was more marked with the better balanced diet (16% protein). During the first half of pregnancy, the increase in intake occurred principally at the beginning of the night (compensatory reaction). Later on, the stimulation extended to the last part of the night (anticipatory reaction). The nocturnal predominance of feeding activity was maintained in pregnant females in spite of their increased metabolic requirements.