The Influence of Diet and Fat Cell Size on Glucose Metabolism, Lipogenesis, and Lipolysis in the Rat[*]

Abstract

These experiments have evaluated the effects of caloric intake, dietary composition, and the size of fat cells on the response to exogenous insulin and on the metabolism of glucose in vivo and in vitro. The size of fat cells was varied by dietary modification. One group of rats was fed a restricted intake on Laboratory Chow and had the smallest fat cells. Rats fed ad lib with a diet containing two-thirds of its calories from Chow and one-third from corn oil had the largest fat cells. Intermediate cell size was achieved in two groups of rats by feeding Laboratory Chow ad lib and by isocalorically pair-feeding the other group with the two-thirds Chow - one-third corn oil diet.

The following conclusions seem warranted: 1) Isocaloric substitution of fat for carbohydrate impaired the response to insulin in vivo even though fat cells did not change in size (ad lib fed Chow groups vs. isocalorically pair-fed Chow fat group). 2) Lipolysis in vitro as measured by glycerol release was influenced by fat cell size but dietary composition over the range studied had little influence. 3) For the response to insulin in vitro, prior nutritional history is more important than the size of the adipocytes.

Key words

Caloric Intake - Diet - Fat Cell Size - Lipolysis - Lipogenesis

1 Supported in part by Grant AM-15165 and RR 425 from the National Institute of Health.

1 Supported in part by Grant AM-15165 and RR 425 from the National Institute of Health.