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ARS Home » Southeast Area » Little Rock, Arkansas » Arkansas Children's Nutrition Center » Research » Publications at this Location » Publication #196590
Title: CALORIC INTAKE AND DIETARY FAT TO CARBOHYDRATE RATIO INFLUENCE BODY WEIGHT ACCRETION AND ADIPOSITY IN RATS FED BY TOTAL ENTERAL NUTRITION

Author
item SHANKAR, KARTIK - ACNC/UAMS
item FERGUSON, MATTHEW - ACNC
item DALLARI, TAMMY - ACNC
item RONIS, MARTIN - ACNC/UAMS
item BADGER, THOMAS - ACNC/UAMS

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/6/2006
Publication Date: 3/27/2006
Citation: Shankar, K., Ferguson, M.E., Dallari, T., Ronis, M.J., Badger, T.M. 2006. Caloric intake and dietary fat to carbohydrate ratio influence body weight accretion and adiposity in rats fed by total enteral nutrition [abstract] The FASEB Journal. 20(4):A581.

Interpretive Summary: As obesity continues to be one of the most important public health issues, the understanding of the how composition of our diets affects our ability to gain weight is becoming increasingly important. Consumption of high energy high-fat diets leads to weight gain and adiposity in rodents. However the relative roles of higher caloric intake vs. increased dietary fat remain unclear. On the other hand, low carbohydrate high fat diets, like the Atkins diet, claim to promote weight loss. To examine the affect of changes in dietary composition on weight gain in rats, we fed rats with either high fat or high carbohydrate diets at either the normal caloric intake or modest overfeeding (15% excess). Our studies showed that overfeeding of diets high in carbohydrate or fat led to greater weight gain and body fat accumulation. However, surprisingly, increased carbohydrate content in the diet increased weight gain and fat accumulation even when calories were normal (not overfed), suggesting that simple carbohydrates are more readily converted to body fat, compared to an isocaloric intake of fat. Data from our studies also suggest that carbohydrate-driven adiposity also predisposed rats to develop insulin resistance, a pre-diabetic condition commonly associated with obesity.

Technical Abstract: Consumption of high energy high-fat diets leads to weight gain and adiposity in rodents. However the relative roles of higher caloric intake vs. increased dietary fat remain unclear. Low carbohydrate high fat diets, like the Atkins diet, claim to promote weight loss. We employed a total enteral nutrition model to evaluate roles of caloric intake and dietary fat to carbohydrate ratio in mediating weight gain. Female Sprague-Dawley rats were fed either 187 kcal/ kg3/4/d (normal calorie, NC, NRC requirements) or 220 kcal/kg3/4/d (overfed 15% excess calories/d, high calorie, HC) via intragastric infusion. NC and HC diets were either low fat (LF, 5% calories from fat, corn oil) or high fat (HF, 45% calories from fat, ~20-fold higher fat/carbohydrate than LF). LF and HF diets were isocaloric. Protein (casein) was 20% of caloric intake and carbohydrate calories contributed to 75% and 35% in the LF and HF diets, respectively. A separate group of rats were fed regular rodent chow (ad libitum). After 6 weeks of infusion of diets, body weights (BW) of rats fed NC-HF matched ad lib fed controls. HC-HF rats showed significantly higher (152%) BW compared to NC-HF and ad lib fed controls. However, both NC and HC rats fed LF diets consistently showed ~20% higher BW compared to rats fed HF diets. Consistent with BW data, body composition as assessed by whole animal Echo MRI revealed higher fat mass/BW in rats fed HC diets. Greater fat mass/BW was also observed in NC-LF rats as compared to NC-HF fed rats. Analysis of oral glucose tolerance tests to evaluate insulin resistance as a function of caloric and diet fat intake is ongoing.