As Hippocrates, the father of modern medicine famously said; “Our food should be our medicine, our medicine should be our food. But to eat when you are sick is to feed your sickness.”
What he means is that our body has a natural fasting instinct. It is something that we do instinctively. Think about when you're feeling sick, when you have a cold or any other illness, the last thing you think about is eating a buffet. Our bodies are designed to fast, store food when available, and release it in times of scarcity. That happens naturally to us and is not something that we are forced to do.
Fasting is a longstanding part of many religious traditions, including Islam, Buddhism and Christianity. A form of fasting known as intermittent fasting has also gained popularity as a weight-loss tool. Religions will not prescribe fasting to their believers if it brings harm to them. In fact, it’s very beneficial. We know from science that there are so many medical benefits of fasting:
Improved mental clarity and concentration
Weight and body fat loss
Lowered blood insulin and blood sugar level
Reversal of Type 2 diabetes
Increased energy and growth hormone
Lowered blood cholesterol
Prevention of Alzheimer’s disease (Type 3 DM)
Longevity
Reduction of inflammation
Activation of cellular cleansing by stimulating autophagy
Essentially, fasting cleanses our body of toxins and forces cells into processes that are not usually stimulated when a steady stream of fuel from food is always present.
When we fast, the body does not have its usual access to glucose, forcing the cells to resort to other means and materials to produce energy. As a result, the body begins gluconeogenesis, a natural process of producing its sugar. The liver helps by converting non-carbohydrate materials like lactate, amino acids, and fats into glucose energy. Because our bodies conserve energy during fasting, our basal metabolic rate (the amount of energy our bodies burn while resting) becomes more efficient, thereby lowering our heart rate and blood pressure.
Ketosis, another process that occurs later into the fast cycle, happens when the body burns stored fat as its primary power source. This is the ideal model for weight loss and balancing blood sugar levels.
Fasting puts the body under mild stress, which causes our cells to adapt by enhancing their ability to cope. In other words, they become strong. This process is similar to what happens when we stress our muscles and cardiovascular system during exercise. As with exercise, our body can only grow stronger during these processes when there is adequate time to rest and recover. That’s why short-term fasting is recommended.
Fasting and Cancer
In the past decade, we have witnessed remarkable advancements in cancer treatments but there is a crucial need for more effective strategies to reduce the side effects of cancer treatments.
Many patients with cancer experience different kinds of side effects (I.e. nausea, vomiting, fatigue, hair loss, neuropathy, etc) from their chemotherapy or radiotherapy treatments, and this has profoundly affected their quality of life.
There has been growing evidence in clinical studies that caloric restriction or fasting around chemo/radiotherapy not only helps to counteract many of the side effects of the cancer treatment but also enhances the patient’s response to cancer therapy.
Fasting causes normal healthy cells to switch to a protective mode against the therapy. However, cancer cells with different metabolic modes are not able to perform the same switch, making them more vulnerable to cytotoxic therapies.
According to the research conducted by Dr Valter Longo, combinations of caloric restricted diet/fasting and chemotherapy/radiotherapy/immunotherapy are promisingly able to increase treatment efficacy, prevent treatment resistance, and reduce side effects.
Therefore, fasting 24-48 hours BEFORE and 24 hours AFTER each chemo/radiotherapy is recommended. However, cautiousness needs to be exercised on frail or malnourished patients who are at risk of malnutrition. It is advisable that a patient's nutritional status should be monitored carefully by a trained medical professional.
References:
https://www.fondazionevalterlongo.org/new-clinical-study-on-the-combination-of-fasting-diet-and-chemotherapy/?lang=en
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6530042/