Every day we hear of a new diet to adopt, with the many health promises of, for example, detoxing, weight loss, fat loss and longevity. Most come with fancy methods combining special ingredients and complicated protocols, until sometimes we find ourselves confused and unsure about which to choose.
The latest trend appears to be fasting, but why is it popular? In fact, fasting is not new. Hours or days without taking in food is something we humans have been doing for a very long time, and it occurs throughout the world, a way of treating disease since ancient times.
What exactly is fasting?
Fasting is a dietary practice of voluntarily refraining from consuming food and drink containing calories for a set period.
Humans have an innate fasting instinct. And evolutionary adaptation has made our bodies very efficient at storing energy reserves and drawing upon them when food supplies are scarce.
Benefits of fasting
The benefits of fasting were unclear until a Japanese cell biologist, Yoshinori Ohsumi, won the Nobel Prize for Medicine in 2016 for his research on how cells recycle and renew their contents through a process called autophagy. Autophagy helps slow down the ageing process and has a positive impact on cell renewal. And the process which stimulates autophagy is fasting. This scientific confirmation may well have led to the increased interest in fasting we see today.
What exactly is autophagy?
The term ‘autophagy’ literally means ‘self-eating’.
Autophagy is a natural mechanism by which cells clean out damaged components including proteins and other waste products within the cell. It also recycles parts of itself into new components which can be used for cellular repair.
Evidence from animal studies suggests that the health benefits of autophagy are protection from diseases such as cancer, neuro-degenerative disorders, infections, inflammatory diseases, ageing and insulin resistance. Unfortunately, as with many physiological processes in the body, the function of autophagy declines with age.
How long do you need to fast for autophagy to begin?
Scientists have found that fasting for 12-24+ hours triggers autophagy. However, only a few studies measuring fasting and autophagy in humans exist.
Who should fast?
Healthy people in general can try fasting for a short period of time. People who should not fast include women who are pregnant or breastfeeding, those with severe medical conditions, anyone suffering from an eating disorder, the elderly and children. It is important to note that fasting for long periods of time should always be done under the supervision of a doctor.
How else can we induce the autophagy process?
Autophagy can be induced by various stress conditions, not only fasting. Calorie restriction, exercise, and eating certain types of food can also induce cells to clean house.
Calorie restriction: Generally, a 10-40% reduction in overall caloric intake is among the most potent autophagy inducers. Clinical research indicates that long-term calorie restriction (3-15 years) leads to an increased expression of autophagy genes and higher levels of molecules involved in removing dysfunctional proteins and organelles.
Exercise: Movement also induces autophagy in muscle tissue. Autophagy markers immediately increase after short periods of intense exercise, and also over the course of longer, moderate-intensity training sessions. Exercise that induces autophagy includes high-intensity interval training (HIIT), weightlifting and resistance training. Interval walking (fast alternating with slow) can also induce the process.
Foods that promote autophagy: Recent studies demonstrate that polyphenols, beneficial compounds found in plants, may play a role in inducing autophagy. Examples of foods containing polyphenols are green tea, red wine, grapes, apples, berries, nuts, soybeans, onions, turmeric and milk thistle.
Personalising your diet plan
Before you start any diet plan, you should discuss it with your doctor. If you are quite healthy, you can experiment with fasting at home and incorporating light activity, which can distract from feeling hungry. Drink lots of plain herbal tea, especially if you find yourself craving, and observe how you feel during the fast. Note any changes and/or results you see in your body. Equally important is to listen to your body.
If you do not feel well while fasting, simply return to eating a well-balanced and nutritious diet. You can combine this with other methods of inducing autophagy, for example the right exercise. The most important thing is to make sure to eat a healthy balance of nutrients while maintaining a healthy lifestyle. This is a good way to prevent chronic disease and promote longevity.
In the meantime, the research on fasting and its long-term effects and mechanisms in humans continues.