A Better Quality of Life and Less Fatigue: New Evidence of the Benefits of Fasting During Chemotherapy

  • by: Fondazione Valter Longo Onlus Editorial Staff
  • April 20th, 2020

Every year, 8.8 million people worldwide die of cancer and although the recovery rates are increasing, it is estimated that these figures will reach 13 million in 2030. Recently, the journal BMC Cancer published the results of a new clinical trial confirming the benefits of fasting on the quality of life for women diagnosed with breast and ovarian cancer and undergoing chemotherapy, and specifically in the ability of fasting to alleviate fatigue [1]. The paper is authored by a team of researchers from the Department of Internal and Integrative Medicine at the Immanuel Krankenhaus Center, in collaboration with the Institute of Social Medicine, Epidemiology and Health Economics of the Freie University, both in Berlin.

Today, chemotherapy— together with radiotherapy and surgery, is the predominant and most effective treatment to fight cancer. However, cancer patients have long weighed the effectiveness of chemotherapy with its heavy toll on the quality of life. As such, modern medicine—even in the field of oncology— is beginning to pay greater attention to experimental therapeutic approaches. One approach that deserves special recognition are fasting and mimicking diets. This innovative intervention has increasingly produced promising results, both in basic research and clinical trials.

The clinical trial conducted in Berlin studied the effects of fasting on a pool of 34 patients, with an average age of 51 years and no less than 18— all with a diagnosis of breast cancer or ovarian cancer and medical recommendations to undergo standard chemotherapy treatment. The fasting regime, which began 36 hours before the chemotherapy cycles and ended 24 hours after, was administered in two forms: the first group, about half of the patients, underwent Fasting Mimicking Diet (FMD) in the initial phase of chemo, while the second group fasted in the final stage. During the fasting period, patients followed a FMD whose 350 kcal per diem limit—consisting of tea,and vegetable juices and broth. Patients were monitored for the duration of treatment and, in all the observed cases, FMD proved tolerable, causing only minor headaches, nausea or hunger that did not interfere with normal daily activities. Weight loss and reduction of body mass index, typical consequences of chemotherapy, were also limited, with an average variation of less than 1.5 kg in both groups. The improvement in quality of life and reduction of fatigue were more evident for patients who underwent fasting in the initial phase of chemo cycles. This result could be attributed to several factors, notably that fasting appears more effective in preventing the side effects of therapy, than in reversing them.

While the results of this pilot study are certainly encouraging, the implementation of this procedure still requires a degree of prudence in order to avoid potential risks to patients’ health. In particular, it should be noted that not all cancer patients can undergo fasting. Body mass index values lower than 19 kg / m2, a frail physical constitution, and major diseases are incompatible with therapeutic fasting. Rather, for other patients, fasting during chemotherapy treatments is not only feasible but potentially effective. This study confirms as well as adds to the conclusions of previous experimental studies that, since 2008, have demonstrated the efficacy of therapeutic fasting to diminish side effects in mice, but also contributes to the findings of various pilot clinical trials. Regardless of the type of tumor, different fasting protocols in combination with chemotherapy have proven to be safe and even capable of reducing the side effects of pharmacological treatment [2-4]. Hence, fasting can be used as an important tool to enhance the efficacy of chemotherapy. Its primary contribution appears to be that it helps the chemotherapy drugs to identify the cancer cells—under the correct environmental conditions.

Nonetheless, as the antitumor drugs are increasingly specific and selective, detrimental effects on healthy and actively proliferating cells, such as blood cells, hair follicles or reproductive organs, remain unavoidable. Although at the termination of the therapy, in most cases, such cells resume normal activity, it is undeniable that the problem of cytotoxicity can have negative consequences both for the effectiveness of the therapy itself, triggering even some degree of resistance to the chemo drugs, as well as the formation of secondary tumors, especially after several years of treatment.

Under -nutrient-poor conditions (fasting), cancer cells exhibit greater sensitivity to antineoplastic drugs than do normal cells. This phenomenon, referred to as “differential stress resistance”, demonstrates a different metabolic behavior in healthy cells than it does in diseased cells, and is commonly observed in both the simplest and the most complex organisms, such as humans [5-6]. From a biochemical point of view, the protective effect of fasting translates into a significant reduction in blood glucose, insulin, and IGF-1 (Insulin-like Growth Factor) levels, which can facilitate cancer growth. In such a context, where the efficacy of chemotherapeutics is naturally enhanced, the need to increase their doses or to develop more aggressive drugs can be reduced. Thus, investing in such research is costly, but represents a crucial resource in terms of producing tangible benefits for patients.

Indeed, FMD can be an enhancement of conventional cancer therapies given that it does not require an excessive financial investment and is potentially effective both in protecting against various cancer treatments and in increasing their anti-tumor toxicity. Still, further clinical trials are necessary to confirm the efficacy of this approach and thus obtain unanimous recognition by the scientific community.


  1. Bauersfeld S.P. et al. (2018) The effects of short-term fasting on quality of life and tolerance to chemotherapy in patients with breast and ovarian cancer: a randomized cross-over pilot study. BMC Cancer 18: 476.
  2. Safdie F.M. et al. (2009) Fasting and cancer treatment in humans: A case series report. Aging (Albany NY).1:988-1007.
  3. de Groot S. et al. (2015) The effects of short-term fasting on tolerance to (neo) adjuvant chemotherapy in HER2-negative breast cancer patients: a randomized pilot study. BMC Cancer 15:652.
  4. Dorff T.B. et al. (2016) Safety and feasibility of fasting in combination with platinum-based chemotherapy. BMC Cancer 16:360.
  5. Lee C and Longo VD. (2011) Fasting vs dietary restriction in cellular protection and cancer treatment: from model organisms to patients. 30:3305–16.
  6. Raffaghello L. et al. (2008) Starvation-dependent differential stress resistance protects normal but not cancer cells against high-dose chemotherapy. Proc Natl Acad Sci U S A 105:8215–20.

Nicoletta Guaragnella


Researcher at the Institute of Biomembranes,
Bioenergetics and Molecular Biotechnologies of the National Research Council, Bari
Scientific communicator


Join our Newsletter to stay updated with the Foundation projects and new advances in diseases prevention and treatment.