Tj. Lauterio et al., DEVELOPMENT AND CHARACTERIZATION OF A PURIFIED DIET TO IDENTIFY OBESITY-SUSCEPTIBLE AND RESISTANT RAT-POPULATIONS, The Journal of nutrition, 124(11), 1994, pp. 2172-2178
A purified moderately high fat diet has been developed to examine diet
-induced obesity in rats. Male Sprague-Dawley rats were fed this or an
AIN-76A diet for 15 wk and energy metabolism indices were monitored.
Food intake, body weight and water. balance indices were recorded on a
weekly or daily basis. Over the 15-wk period, rats fed the experiment
al diet diverged into two groups differing in the rate of body weight
gain. Animals were labeled as ''gainers'' or ''resisters'' depending o
n their susceptibility to obesity. Following the dietary period, rats
were decapitated and trunk blood was collected for glucose and insulin
measurements. Gainers consumed slightly more energy than resisters ov
er the experimental period (P < 0.05), but due to greater fecal energy
loss, absorbed energy did not differ. Hence gainers became obese with
out significantly altered energy retention. Urinary creatinine, urea n
itrogen and water balance were not different between the groups and co
nsequently could not explain body weight differences. Further, gainers
had significantly greater plasma glucose concentration than controls,
indicating a potential for these animals to become diabetic. Results
suggest metabolic differences must account for the divergence in weigh
t gain observed in the two groups. The dietary model characterized in
this study should provide a useful tool to study diet-induced obesity
and to determine its underlying mechanism.