Intermittent fasting (IF) is receiving plenty of attention in the press and scientific research regarding its potential health benefits. So should you try it?
What is Intermittent Fasting?
While it may appear to be the latest dietary approach to hit the press, fasting has been around for as long as man has walked the earth. Our ancestors would typically experience times of food scarcity. In addition many of the world’s religions recommend periods of fasting to purify the body and spirit.
Intermittent fasting is a pattern of eating where you restrict the hours of feeding. There are many different ways to undertake a fast. Perhaps the most basic is what is often termed ‘Time Restricted Eating’. This is where you fast overnight for at least 12-14 hours. This time of fasting follows our circadian rhythm and can be a useful place to start if you are considering incorporating fasting.
Below are a few other fasting approaches.
5:2 Intermittent Fasting: As it name implies you fast on two non-consecutive days within a week. On these days you reduce your calories to around 600 calories, while the other 5 days are normal non-restricted days. It is important to ensure nourishing meals particularly on the low calorie days.
16:8 Intermittent Fasting: This style of fasting usually means eating an early dinner, say around 6 pm, and then nothing else until late the following morning. Some people simply eat an early lunch and skip breakfast altogether. This allows the fasting period to be around 16 hours and then eating without an 8 hour window.
Whole Day Fasts – This pattern involves fasting for 24 hours or more. This is often undertaken on two non consecutive days per week.
Fasting Mimicking Diet (FMD) – Developed and researched by Dr Valter Longo, this pattern of eating involves five days of consecutive eating at a reduced calorie level (around 600-700kcal) which is relatively low in protein and with a moderate carbohydrate and fat intake. This style of eating as the name implies mimics fasting without totally excluding food. FMD has also be subject to numerous research highlighting health benefits. This cycle of fasting can be repeated once a month or once every 3 to 4 months a year.
What are the Benefits of Intermittent Fasting?
It is the longer types of fasts where most of the research has focused.
Autophagy. Fasting induces a process called autophagy (known as self eating) – this is the primary mechanism which relates to the disposal of waste and the repair of our body cells. When you fast the body through autophagy supports cellular clean-up that leads to cellular regeneration and an increase in circulating stem cells. This is mainly why fasting is recommended in anti-aging diets. In fact one research paper stated ” Calorie restriction is widely considered to be the most robust and reproducible way of extending health and longevity”. It can help with maintaining muscle mass and offset some of the degenerative processes linked to aging.
Energy levels. Partly as a consequence of autophagy one of the benefits of fasting is an increase in mitochondrial biogenesis and function. In essence you increase mitochondria function which are your energy factories.
Weight Loss. For many people the reason they try fasting is to improve body composition. Several studies have shown that intermittent fasting is associated with weight loss. Interestingly rather than losing muscle mass research shows that intermittent fasting can cause a shift in metabolism that preserves muscle. So intermittent fasting can be effective for reducing fat mass and improving body composition.
The shift in metabolism from glucose to fat is more significant after 16-18 hours of fasting, suggesting that the longer day fasts have additional benefits.
It is worth mentioning that if you exercise intensely daily or are looking to build muscle and strength at the gym the longer fasts may be counterproductive. In these cases the 16/8 approach may be better. While burning fat for energy is great you do not want the body converting amino acids into glucose. One study found breakdown of muscle tissue was more evident after 16 hours . You may also wish to make your evening meal before the fast rich in slow releasing protein (e.g caesin) to help maintain muscle mass. Other research suggests this may also elevate human growth hormone – again useful if you are looking to improve body composition
The good news is that short term fasting does not appear to cause a decline in metabolism either. One study found drop in metabolic rate did not happen until 60 hours of fasting and even then it was only slightly.
Heart Health – A noticeable benefit from fasting is an improvement in many cardiovascular health markers. Studies have shown it can lead to a significant reduction in cholesterol and LDL cholesterol and triglycerides. There also appears to be benefits when it comes to glucose levels, insulin and improving insulin sensitivity.
Inflammation & Immune Health – Fasting and autophagy leads to the reduction in inflammatory markers and oxidative stress – beneficial both for those with ongoing inflammatory conditions or allergies. It may also help promote brain health by lowering neuroinflammation. In fact chronic neuroinflammation is increasingly associated with neurodegenerative diseases like Alzheimer’s and mood disorders such as depression. Another benefit of fasting is an increase in Treg cells and decrease in TH17. TH17 is associated with chronic inflammatory conditions including autoimmune conditions.
Should you try Intermittent Fasting?
Fasting may not be suitable for everyone. Fasting is not recommended during pregnancy or breastfeeding. If you are underweight or suffering with body dysmorphia then fasting is not appropriate. It may also not be beneficial if you have adrenal fatigue or clinical hypothyroidism. If you have diabetes and on medications then seek professional advice before embarking on fasting programmes. If you do embark on fasting then remember it does not give you licence to eat rubbish – focus on nourishing food and consider taking a multivitamin and mineral formula to ensure optimum nutrition.