Intermittent fasting or time restricted eating refers to a pattern of eating that takes advantage of the body’s natural circadian clock, eating only when your metabolism is optimal, switching between stages of fasting whereby you only allow yourself to consume water or black coffee and non-fasting.
A stated by Dr. Rhonda Patrick, who I personally like to follow on you tube, intermittent fasting has been shown to have beneficial effects on health and longevity. When you fast, you deactivate growth pathways (like IGF-1 and mTOR) both of which are activated by amino acids, recent studies have also shown increases in male testosterone production, increases in growth hormones, a reduction of free radicals and a reduction in body inflammation.
It is believed that alternate-day calorie restriction may prolong individual life spans and deter lifestyle diseases such as diabetes, high cholesterol and vascular disease. Intermittent fasting and caloric restriction are forms of dietary restriction (DR), which is sometimes referred to as dietary energy restriction (DER).
Basically the idea behind following this diet is that it allows us to work within our body’s natural circadian rhythm. In the morning we produce a hormone called cortisol to wake us up, as the day goes on, our cortisol levels decrease and at night our melatonin levels rise making us sleepy.
There is a few different types of intermittent fasting;
Intermittent fasting – fasting for up to 24 hours.
Prolonged fasting – when you start fasting for 2 days or longer.
Time-restricted eating – Involves eating when your metabolism is optimal, when you’re not eating, your fasting.
With time restricted eating this might mean fasting for 16 hours, and eating all your food within an 8 hour window.
Mattson, Mark P. (2008). "Dietary factors, hormesis and health" suggest that intermittent fasting may function as a form of nutritional hormesis, a process in which a low dose of a nutritional stressful stimulus activates an adaptive response that increases resistance to moderate or severe stress. Among stressors which may induce hormetic effects in humans are exercise, ethanol, pharmacological agents and dietary restriction (both every-day caloric restriction and intermittent fasting).
Heilbronn et al. (2005) states that alternate-day fasting may encourage fat oxidation. Fatty acid oxidation is the process of fatty acids breaking down which releases energy. Fatty Acids are the residue created after fats are broken down. These fats can be stored and utilized at a later time for energy. Fatty Acids are essential for the human body because they help move oxygen through the bloodstream, aid cell membrane development, function and strength, and, they are necessary for your tissues and organs to work properly. Fatty acids also help reduce total cholesterol because they help arteries eliminate cholesterol build up and can help lower triglycerides. In addition to these essential roles, fatty acids also help prevent wrinkles and help keep skin healthy and elastic.
With intermittent fasting and prolonged fasts your body shifts from glucose/ carbohydrate metabolism, to metabolizing fatty acids and key tone bodies are produced. Ketone bodies have been shown to act as signalling molecules which activate genetic pathways that are known to delay age related diseases. Basically Ketones = anti aging.
Intermittent fasting is an increasingly popular diet plan that hit the headlines in 2012 and has been popular amongst many dieticians and athletes since. Proponents claim that in addition to weight loss, the diet can lead to longer life and protection against disease, particularly conditions such as dementia and Alzheimer's disease.
Intermittent fasting is one of the current diet trends taking the world by storm and like any diet trend, there are pros and cons that could lead to it not being something that is sustainable for you. The use of sporadic eating patterns to lose fat can be effective but that does not necessarily mean that it is the healthy option for everyone, sustainable long term or beneficial for athletes.
Experts and non-experts in nutrition fields recommend a variety of meal frequency or fasting methods- fasting every 16 hours, every 20 hours, all day, every-other day, every third day, twice a week or once a week.
At the end of the day intermittent fasting can produce fat loss but is definitely not the only method, or the best. From a physiological perspective it has the potential to compromise your bodies’ ability to regulate itself and leave you tired and fatigued. I think it’s important to listen to your bodies’ needs and see if these forms of eating work for you. Each type of fasting has its own benefits and it is suggested to combine them and do them periodically, time restrict your eating 1-7 days a week, do periods of prolonged term fasts or do an intermittent fast for up to 24hours every now and then J
For more information I would check out Dr. Rhonda Patrick on Youtube or have a listen to “The Drive Podcast’ with Peter Attia J