Low-Carbohydrate Diet Versus Caloric Restriction: Effects on Weight Loss, Hormones, and Colon Tumor Growth in Obese Mice

Abstract

Our objective was to compare the effects of a low-carbohydrate diet to a high-carbohydrate/calorie-restricted diet on weight loss, hormones, and transplanted colon tumor growth. Eighty male C57BL/6 mice consumed a diet-induced obesity regimen (DIO) ad libitum for 7 weeks. From Weeks 8 to 14, the mice consumed a 1) DIO diet ad libitum (HF); 2) low-carbohydrate diet ad libitum (LC); 3) high-carbohydrate diet ad libitum (HC); or 4) HC calorie restricted diet (HC–CR). MC38 cells were injected at Week 15. At the time of injection, the HC–CR group displayed the lowest body weight (25.5 ± 0.57 g), serum insulin-like growth factor I (IGF-I; 135 ± 56.0 ng/ml), and leptin (1.0 ± 0.3 ng/ml) levels. This group also exhibited the longest time to palpable tumor (20.1 ± 0.9 days). Compared to the HF group, the HC group exhibited lower body weight (39.4 ± 1.4 vs. 32.9 ± 0.7 g, respectively), IGF-I (604 ± 44.2 vs. 243.4 ± 88.9 ng/ml, respectively), and leptin (15.6 ± 2.2 vs. 7.0 ± 0.7 ng/ml, respectively) levels but similar tumor growth. IGF-I levels were lower in the LC group (320.0 ± 39.9 ng/ml) than the HF group, but tumor growth did not differ. These data suggest LC diets do not slow colon tumor growth in obese mice.

ACKNOWLEDGMENTS

The authors thank Research Diets, Inc., for feed donation, the students in the Nutrition 142L Fall 2005 and Spring 2006 laboratory course for feeding the mice, and Laurence Denis, MD, for assisting with tumor dissection. The MC38 cells were generously provided by Dr Shoshana Yakar from the National Institute of Diabetes and Digestive and Kidney Diseases. This study was funded in part by the Department of Human Ecology at the University of Texas at Austin.

Notes

^a Abbreviations are as follows: HC, high carbohydrate; HF, high fat; LC, low carbohydrate; HC-CR, HC, calorie restricted.