Intermittent Fasting Problem?

While there are a number of studies supporting benefits for of intermittent calorie restriction (ICR), a disturbing new study in mice suggests negative effects of ICR: an increase in cancer stem cells (CSCs) and enhancement of epithelial to mesenchymal transition, which promotes metastasis.  Keeping the mice in “continuous calorie restriction had no effect on tumor weight, metastasis, or the number of CSCs in tumors or blood” – not bad but not good either.  Speaking for myself, I eat three healthy meals per day (with approximately 12 hours between dinner and the subsequent breakfast), avoid overweight/obesity, and avoid any “fad diets.”  That’s what I’m doing, that is not necessarily a recommendation to anyone else.  Abstract:

The effect of intermittent calorie restriction (ICR) on cancer is controversial. In this study, we examined the effects of ICR and food content in syngeneic BALB/c mice injected with CT26 mouse colon cancer cells. Mice were subjected to 24-h fasting once a week for 4 weeks, and then provided with a control, high-calorie, or trans fatty acid-rich diet. While ICR resulted in increases in tumor weights, metastasis and in the number of cancer stem cells (CSCs) in the tumors or blood of mice fed the control and high-fat diets, it had no effect on body weight after 4 weeks. In particular, we detected increases in the numbers of CSCs in the tumor or blood on the day after starvation, when food overconsumption was detected. Conversely, continuous calorie restriction had no effect on tumor weight, metastasis, or the number of CSCs in tumors or blood. In the post-starvation period, energy metabolism in the tumor was altered from oxidative phosphorylation to glycolysis/lactate fermentation, with the acquisition of the epithelial-mesenchymal transition (EMT) phenotype. Hyperglycemia at the post-starvation period induced the expression of insulin-like growth factor-1, hypoxia-induced factor-1α and Nanog, as well as the phosphorylation of Stat3. Taken together, these findings suggest that ICR induces an increase in the number of CSCs and enhances EMT by promoting the Warburg/Crabtree effect following post-fasting food overconsumption.