METABOLIC ADAPTATIONS TO A “STUFF AND STARVE” FEEDING PROGRAM. I. STUDIES OF ADIPOSE TISSUE AND LIVER GLYCOGEN IN RATS LIMITED TO A SHORT DAILY FEEDING PERIOD*

Abstract

Many obese people consume most of their food within a short period each day. We have studied rats allowed access to food for only 2 hours of each 24 for periods of 1 to 7 days in an effort to determine what adaptive changes take place when food intake is manipulated in this way. Groups of 5 or 6 rats were studied at the end of the feeding period with these findings: (1) food intake during the 2 hour period remained relatively constant over 7 days and body weight decreased slightly; (2) in vitro incorporation of C-14 acetate into lipids by adipose tissue increased over thirty-fold within the period of study while incorporation of C-14 into liver lipids increased only fourfold; (3) glucose-6-phosphate and 6-G-P dehydrogenase activity in adipose tissue rose about 400% but did not change in liver; (4) liver glycogen increased during the first 3 days of the study and remained relatively constant thereafter; (5) the free fatty acid content of adipose tissue fell gradually during the period of study; (6) liver glycogen in animals limited to a daily feeding period of 2 hours for 4 or 5 days was much greater after 24 hours of fasting than fasted controls who had been allowed to eat ad libitum. A major metabolic consequence of limited feeding periods appears to be greatly increased fat synthesis.