Examining trends of public interest in fasting and cancer-fasting clinical trials in the U.S.

Background : Interest in fasting related to cancer has increased as evidence suggests fasting may have anti-cancer benefits. Fasting has been shown to deprive cancer cells of nutrients, thereby inhibiting their growth and proliferation and making them more sensitive to chemotherapy in preclinical studies. Clinical trials incorporating fasting have grown over the years; however, recruiting participants remains challenging due to eligibility criteria, protocol complexities, and public interest. Identifying public interest in fasting and cancer, as well as in cancer-fasting clinical trials could help improve methods to raise awareness of the importance of fasting clinical trials and increase the number of trials to improve cancer. Objective : To determine if public interest in fasting and cancer corresponds with cancer fasting clinical trials. Methods: U.S. Google Trends data were queried by region from January 2004 to October 2025 to identify public interest in fasting overall (across all categories) and by cancer. Data are presented using relative search interest (RSI) ranging from 0 to 100, with 100 indicating the most searched, 50 representing half as many searches, and zero or null indicating insufficient data. Data from clinicaltrials.gov and Surveillance, Epidemiology, and End Results (SEER) Program were queried and used for trend analysis. Results: Public interest in fasting in general, not restricted to cancer, across all categories was low prior to 2011 (RSI generally <20). RSI began to increase slightly after 2011 and grew to 30 by 2016. There was a sharper increase after 2016 with interest peaking in November 2019 (RSI=100) but has remained consistently high since (RSI range 50-80 since 2019). When examining only cancer interest, fasting related to cancer remained low with occasional spikes, but began to increase after 2016, in-line with the increased interest in fasting not limited to cancer. Indeed, interest in fasting and cancer largely mirrored general interest in fasting trends. Among all states with data, most had an RSI of 75 or higher for fasting across all categories. From 1991 to the present, 255 clinical trials have been initiated on fasting and cancer. The number of new trials per year slightly rose from 2000 to 2008, then dipped a bit, and then grew again slightly from 2013 (15 new trials in 2013) to 2025 (18 new cancer-fasting trials in 2025). Conclusions: Public interest in fasting and cancer in the past ~12 years has grown 2-3-fold and been sustained at a high level over the past ~8 years. In contrast, the number of new trials started per year has barely changed over this time. While the reasons fasting trial numbers have lagged public interest are unknown, we speculate challenges enrolling and receiving funding for dietary trials may play a role. Given promising preclinical data coupled with public health interest, there should be increased funding and support for fasting trials in patients with cancer.