From the Guidelines
Fasting should not be used as a replacement for conventional cancer treatments, but short-term fasting (24-72 hours) around chemotherapy sessions may help reduce side effects and potentially enhance treatment effectiveness, as suggested by recent guidelines 1. When considering fasting and cancer, it's essential to prioritize the patient's overall health and treatment plan. The American Society of Clinical Oncology (ASCO) guideline on exercise, diet, and weight management during cancer treatment emphasizes the importance of a healthy lifestyle, including regular exercise and a balanced diet, in improving treatment tolerability and enhancing fitness and functional status in patients undergoing treatment 1.
Some key points to consider:
- Fasting may have potential benefits for cancer patients, such as reducing inflammation and promoting cellular repair, but it should be done under medical supervision to ensure adequate nutrition is maintained.
- Short-term fasting (24-72 hours) around chemotherapy sessions might help reduce side effects and potentially enhance treatment effectiveness by putting healthy cells in a protective state while leaving cancer cells vulnerable.
- Intermittent fasting regimens like 16:8 (16 hours fasting, 8 hours eating) or 5:2 (normal eating 5 days, restricted calories 2 days) may also offer benefits, but patients should consult with their oncologist before starting any fasting regimen.
- Patients with cachexia (severe weight loss), those on certain medications, pregnant women, and individuals with diabetes should generally avoid fasting, as it may exacerbate their condition.
- The ESPEN practical guideline on clinical nutrition in cancer emphasizes the importance of nutrition in multimodal cancer care and recommends against diets that restrict energy intake in patients with or at risk of malnutrition 1.
- The ESPEN guidelines on nutrition in cancer patients also discourage dietary advice or diets that increase the risk of inducing or aggravating malnutrition, and recommend against fasting during chemotherapy without firm evidence of a benefit 1.
In terms of the benefits and risks of fasting for cancer patients, the current evidence suggests that short-term fasting may be beneficial, but more research is needed to fully understand its effects, and patients should always consult with their oncologist before starting any fasting regimen 1.
From the Research
Fasting and Cancer: Current Research
- The relationship between fasting and cancer is complex, with some studies suggesting potential benefits and others highlighting uncertainties and risks 2, 3.
- Research on intermittent fasting (IF) in cancer patients has yielded mixed results, with some studies indicating improved outcomes and others raising concerns about potential detrimental effects 2, 4.
- A 2021 review of IF in cancer prevention and treatment noted that while some studies suggest potential benefits, high-quality randomized clinical trials are needed to fully understand the effects of IF on human cancer incidence and prognosis 2.
Nutritional Support in Cancer Patients
- Studies have shown that early intervention with nutritional supplementation can halt malnutrition and improve outcomes in patients with colorectal cancer 5, 6.
- Nutritional counseling, supplemental feeding, and pharmacological support have been found to temporarily stop weight loss and improve appetite, social life, and quality of life in cancer patients 6.
- However, the impact of nutritional support on patient survival and disease outcomes is still unclear, with some studies suggesting a potential benefit and others finding no significant effect 5, 6.
Fasting as a Potential Therapeutic Approach
- Some research suggests that fasting could play a key role in cancer treatment by limiting cancer cells' adaptability, survival, and growth 3.
- A 2022 narrative review recommended combining prolonged periodic fasting with standard conventional therapeutic approaches to promote cancer-free survival, treatment efficacy, and reduce side effects in cancer patients 3.
- However, more research is needed to fully understand the effects of fasting on cancer outcomes and to determine the optimal fasting regimens and patient populations for this approach 2, 4.