Humans evolved in environments in which food availability was limited and fasting was often required. A growing body of evidence indicates that the need for intermittent dietary energy restriction, aka fasting, is built into our genetic makeup, and that it has many beneficial effects on our health. This fascinating discovery contrasts dramatically with the dogma we have been "fed" (pun intended!) by the conventional medical paradigm, which argues that we must eat three square meals a day in order to be healthy. Read on to learn about the top ten health benefits of intermittent fasting and how you can incorporate this ancestral practice into your life to promote optimal health.
The Top 10 Health Benefits of Fasting
- Improves insulin sensitivity and promotes weight loss: Fasting reduces blood glucose and insulin levels and improves insulin sensitivity. It has even been proposed as a potential therapy for type 2 diabetes. (1) Dramatically lowering calorie intake for two days out of the week (the 5:2 fasting method – see the “Fasting Mimicking Diet” section below) improves insulin sensitivity while also inducing significant weight loss. (2)
- Strengthens the intestinal immune system: Intermittent fasting has been found to promote intestinal IgA production; this is an immune system protein that protects the gastrointestinal tract from pathogens and toxins. (3)
- Reduces cholesterol and triglycerides and promotes cardiovascular health: Intermittent fasting improves lipid profiles - it increases "good" HDL cholesterol and lowers triglycerides and "bad" LDL cholesterol, which increase the risk of cardiovascular disease. This suggests that intermittent fasting may be a beneficial, safe, and cost-free treatment for dyslipidemia, a condition that is commonly treated with statins and other potentially harmful pharmaceutical drugs. Importantly fasting also decreases resting heart rate and blood pressure, suggesting that it has beneficial effects on autonomic nervous system control of cardiovascular function. (4)(5)
- Decreases cancer risk: By lowering fasting blood glucose and IGF-1, fasting may reduce the risk of cancer, which is promoted by elevations of these two compounds. (6)
- Improves brain health and prevents cognitive decline: Intermittent fasting protects neurons from environmental stressors that may promote disease. This beneficial effect may promote healthy brain aging and stave off cognitive decline and neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. (7)
- Protects against chronic degenerative diseases: Fasting reduces inflammation and boosts the endogenous antioxidant systems of cells. Chronic inflammation and oxidative stress are significant underlying causes of chronic diseases such as obesity, type 2 diabetes, hypertension, and autoimmune disease. This research, therefore, suggests that fasting has a protective effect against these increasingly common conditions. (8)
- Heals the gut: Fasting therapy has been found to improve IBS symptoms such as abdominal pain and diarrhea, suggesting that it has a direct anti-inflammatory effect on the gut. (9) Fasting also promotes the release of ghrelin, a hormone released by cells of the digestive tract, which has anti-inflammatory properties. (10)
- Boosts cognitive function, learning, and memory: Fasting increases the expression of a protein called drebrin, which regulates neuronal growth and is decreased in people with neurodegenerative disease. Fasting also reduces oxidative stress in the brain, thus improving brain function, and promotes the growth of the hippocampus, which is the part of the brain responsible for memory functions. (11)(12)
- Reduces inflammation: Fasting reduces levels of pro-inflammatory cytokines and immune cells in the body. (13)
- Protects against autoimmune disease: Fasting has been found to reduce autoimmunity and reverse symptoms of multiple sclerosis (in animal models) and improves symptoms of lupus erythematosus. (14)(15)
How to practice intermittent fasting
There are three primary ways to go about intermittent fasting: Time-restricted feeding, the 5:2 diet, and the fasting mimicking diet.
This fasting practice involves restricting eating to a specific time window over the course of a day. For example, you could stop eating after dinner at 7 pm and then fast until 11 am the next day for a total of 16 hours. I recommend fasting for at least 16 hours because this length of fasting has demonstrated the most significant health benefits in scientific studies. I practice time-restricted feeding several days a week and have found it to be a fantastic practice for balancing blood sugar, boosting energy, and reducing inflammation.
The 5:2 diet
This method of fasting involves eating regularly for five days out of the week and reducing your caloric intake to 600 calories per day for the next two days.
Fasting mimicking diet
The Fasting Mimicking Diet (FMD) is similar to the 5:2 diet, but it involves restricting caloric intake for more than two days only once a month, rather than for two days every week. This method of fasting is designed to help you achieve the health-promoting effects of fasting while minimizing the adverse physiological effects associated with prolonged caloric restriction. The FMD involves significantly reducing total calorie intake for three to five days each month – after this three to five-day period, normal eating habits are resumed for the remainder of the month. This constitutes one cycle of the FMD. The FMD cycles are continued until desired health results are achieved.
- The FMD is low protein and low carbohydrate.
- Minimal animal products are allowed. Bone broth can be incorporated sparingly, perhaps in the amount of one or two cups per day.
- Protein should come from plant sources.
- Fats should come from healthy plant sources, such as avocado, olive oil, and coconut oil.
- Micronutrients are supplemented in the form of sea salt
- Total caloric intake should be 4.5-7 kcal/lb of body weight.
- Macronutrient ratios: 10% protein, 56% fat, 34% carbs.
Many of my clients and readers have demonstrated an interest in intermittent fasting, making this an important area of focus in my nutrition consulting work. If you are interested in trying intermittent fasting but are not quite sure where to start or which protocol might be best for you, feel free to reach out to me for a free 15-minute phone consult in which we can discuss your nutrition and health needs and determine if intermittent fasting might be a good option for you! I can then help develop a customized fasting plan for you, complete with recipes and supplement recommendations. To schedule your free 15-minute consult, contact me through the Nutrition Consulting page of my website.
I'd love to hear your thoughts on fasting! Have you ever tried fasting before? Did you notice any health benefits? Let me know in the comments below!