Long-term liquid nutrition intake and development of obesity: differences between young and adult rats

Abstract

Obesity is particularly associated with an increased consumption of palatable fat and sugar dense food and beverages. Therefore, we examined the effect of a normocaloric liquid diet (Fresubin) with increased carbohydrate content (constituting 55% of calories) on development of obesity in different developmental periods in male Wistar rats. Fresubin was provided to 3 groups of rats: the first group received Fresubin immediately after weaning (21st day of age) to the end of experiment (150th day of age) for 5 months; the second group was fed with Fresubin from weaning to adulthood (90th day of age) for 3 months; and the third group received Fresubin only in adulthood (from 90th to 150th day of age) for 2 months. The control group was fed with standard pellet chow from weaning to the end of the experiment. Body weight, food and water intake were periodically measured. After terminating the experiment, the adiposity index was determined. Rats fed with liquid nutrition showed increased energy intake and body weight in comparison with the control rats. Interestingly, while obesity in the juvenile rats developed as late as of 13 weeks after the Fresubin intake, the adult rats fed with liquid nutrition had significantly elevated the body weight already 2 weeks after starting the treatment. Increased adiposity index was observed in both groups of rats fed with Fresubin during the whole study as well as the adulthood. Our data indicate that feeding of male Wistar rats with a high carbohydrate normocaloric diet results in a substantial development of obesity. Moreover, exposure of juvenile individuals to obesogenic environment leads, after a certain "latent period", to the development of obesity that may reflect low protein content of used liquid diet or higher resistance of juvenile organism to the obesogenic factors. Finally, based on the data obtained we suggest that Fresubin, with respect to its properties, may serve as a diet for the development of obesity which may exemplify an "obesity model" applicable in small laboratory animals.