Does when we eat make a difference to our health? We know that food choices can impact cancer risk but what if the timing plays a role as well? Evidence shows that fasting may slow cancer growth through a process called autophagy. Through an interdisciplinary research team, I am currently running a small trial testing the effects of intermittent fasting (IF) in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) at BCC-Victoria who not on anti-cancer treatment. Specifically, I am asking whether IF regimens, differing in fasting timing and duration, stimulates autophagy, improves quality of life, impacts gut microbiome, and/or results in clinical benefit (i.e. reduced lymphocyte count). I am also following participants’ safety, ability to follow the fast, and fasting preferences. While early results look promising, I propose growing this study into a larger trial with three phases to clarify the effects of IF on cancer and the microbiome. Understanding these effects may help discover simple diet recommendations for patients with cancer that cause a response in cancer cells or slow cancer progression, are safe and reduce treatment side effects when used alongside current, standard treatments.