Weight loss more important than diet in reversing obesity-cancer link

 29 Mar 2016 - 10:40

Weight loss more important than diet in reversing obesity-cancer link

 

Washington: Researchers striving to break the link between obesity and cancer have found in a new preclinical study that significant weight loss through calorie restriction, but not moderate weight loss through a low-fat diet, was linked to reduced breast cancer growth. 

In the study, researchers with the UNC Lineberger Comprehensive Cancer Center examined whether weight loss via four different diets was linked to reduced tumor growth in laboratory models of breast cancer. While tumor size did not differ between obese mice and obese mice that returned to a normal weight on a low-fat diet, they did find that obese mice that lost significant amounts of weight on three calorie-restricted diets had smaller tumors.
"Based on our results, it appears that the degree of calorie restriction, and hence the amount of weight lost, matters more than the specific dietary changes used to generate the weight loss," said Laura Bowers, PhD, a postdoctoral fellow in the UNC Lineberger Cancer Control Education Program. "Our findings are too preliminary to make any kind of recommendation for people. The overall message is that the breast cancer-promoting effects of chronic obesity may not be easily reversible with moderate weight loss, but more severe weight loss diets may be effective regardless of whether carbohydrate or fat is restricted."
"This is an issue of increasing importance as the obesity epidemic in the United States and throughout the world is increasing the prevalence of obesity-related cancers, and obesity also makes cancers more deadly," Hursting said. "We are working to identify mechanism-based interventions in our experimental models that can reverse the adverse effects of chronic obesity on cancer burden."
In the study, researchers randomized mice to either maintain a normal weight or become obese by consuming a high calorie diet for 15 weeks. The obese mice were then randomly selected to lose weight across 10 weeks on one of four diets: unrestricted consumption of a low-fat diet; a high-carb diet or low-carb diet, both with a 30 percent reduction in calories per day; or the increasingly popular "5:2" diet involving intermittent reduction of calorie intake on two days per week by 70 percent.

QNA