Intermittent fasting – results, side effects and advice for getting started

Intermittent fasting

Intermittent fasting has become a more popular tool in the quest for better health in recent years. This applies to people who want to lose weight, but is at least as popular among exercisers and elite athletes looking to improve their performance. (Source: MDPI).

Fasting is an ancient tradition, often religious or cultural in origin, that has also been used to cure illness. Hippocrates – one of the founders of modern medicine – advocated fasting as a tool to ignite the body’s self-healing mechanism. The ancient Greeks also believed that fasting improved the ability to think, understand, and apply knowledge.

What happens in the body?

When the body is in a phase of fasting, there are good conditions and capacity for cell repair, as the body is put into repair gear rather than digestion gear. Once the stomach has finished with the initial breakdown, the small intestine and liver spend several hours absorbing and distributing nutrients. Just as the brain rests and recovers during sleep, other organs spend up to 5 hours breaking down the last meal.

Cell repair

A type of cell repair, autophagy, is initiated when blood sugar and insulin levels drop significantly. The body breaks down and recycles old cells so that they can work more efficiently again. This happens constantly, but is helped along when there is a lack of nutrients – it is in a way a form of help for self-help.

However, it is not entirely clear when the primary effect of autophagy takes effect, but it may not take more than 2-4 days. So if you are considering fasting for several days, it is recommended to seek expert guidance first.

Gastrointestinal system

Intermittent fasting has a beneficial effect on the gut flora, which helps maintain intestinal and immune function. When we eat, the body must digest and break down food – this releases, among other things, pro-inflammatory markers into the bloodstream as a result of an immune response to the food consumed. Conversely, they decrease if there is no food present in the gastrointestinal system and therefore affect the body to a lesser extent.

Fasting has been shown to reduce gut bacteria, which are associated with systemic diseases in large numbers. It also promotes gut bacteria that rebuild the intestinal lining. The better the gut environment, the easier it can keep out uninvited toxins and focus on letting in useful nutrients.

Dopamine

Dopamine is a neurotransmitter found primarily in the brain and gastrointestinal system. It provides motivation for action and is closely linked to the reward system.
Dopamine secretion increases at the very thought or sight of an upcoming meal and then peaks with the first mouthful.

When the reward system has been suppressed for a long time, dopamine secretion will be correspondingly greater than normal.

This applies to all reward behaviors that upregulate dopamine. This is also one reason why people who fast may experience clearer minds due to this dopamine release, because they achieve success through the self-discipline of fasting and the belief in the beneficial effects of it – a form of placebo.

Circadian rhythm

When we travel across time zones, our bodies spend time adapting to a new circadian rhythm based on exposure to sunlight. Light has a direct impact on our sleep, hunger, immune system and stress management. (Source: Oxford Academic). And just as our circadian rhythm is affected by light, our digestion is similarly affected by a regular circadian rhythm. At night, stomach acid production and intestinal peristalsis are reduced, so our digestion only runs at half speed. (Source: Zarrinpar, Chaix & Panda)

Therefore, our circadian rhythm is an important part of our overall health and nocturnal fasting – during sleep – is important due to cell repair in, among other things, the liver, gastrointestinal system, brain and the rest of the body.

This activates genes related to the body’s circadian rhythm and cell activity, which are important for general health and weight control.

See also the impact our environment can have on our health here.

Longevity – good years of life

Animal studies have shown that fasting prevents and reduces the degree of obesity and lifestyle diseases such as sugar and insulin resistance, liver disease, high cholesterol and age-related decline in heart function. Other studies that measured life years found that mice that simply had access to fewer calories lived 10% longer than a control group. On the other hand, mice with time-restricted access to food lived 35% longer than the control group. (Source: Science).

Studies have been conducted on humans that have similarly promising beneficial effects on lifestyle factors, but we really don’t know whether there are more good years of life to be gained. After all, humans are a more complicated species, but the above knowledge is the starting point for a likely increasing focus here in the future.

 

Diet – are you getting enough protein?

It is important that what you eat is as important as the fast itself. It is therefore recommended to get enough carbohydrates, fat and proteins from good sources. Proteins are made up of amino acids and are known as the body’s building blocks, which are important for maintaining and maintaining a healthy body. As an exerciser, you should consume a minimum of 1.4 – 2.0 grams of protein per kg of body weight per day to maintain or increase muscle mass. This also applies to older people who want to maintain or improve physical function. (Source: Journal of the International Society of Sports Nutrition)

It is not possible for the body to absorb all the protein in a single meal, so they must be distributed over several meals with approximately 20-30 grams of protein per meal. In some cases up to 40 grams/meal if you are training hard or doing heavy strength training, and it may therefore be beneficial for some people to take a protein supplement.

Read more about what protein is good for and how much you should get as a minimum here.

Intermittent fasting – how do I do it?

• The most popular is the 16-hour fasting and 8-hour eating window.
  • Example: eat between 12:00 – 20:00.
• First meal at least 1 hour after waking up. No food intake 2 to 3 hours before going to bed.
• You are allowed to drink water, tea and black coffee – but it must be without milk or sugar, as it will break the fast.
• Drink water! And get enough salts and electrolytes. Especially with caffeinated drinks, which can increase salt excretion.
• Fasting is not necessarily beneficial if you are an athlete or want to significantly increase your muscle mass. You may need to eat over several hours (10-12 hours) to avoid a calorie deficit. In extreme cases, this can manifest as a missed period or, for example, a stress fracture in the foot.
• If you are diabetic, you should contact your doctor before making major dietary changes that will have a major impact on your blood sugar. (Source: National Library of Medicine)

Conclusion

Research is now reasonably conclusive regarding the beneficial effects of fasting. (Source: Cell Reports Medicine). It is important to point out, however, that there are many factors that affect overall health. In humans, it cannot necessarily be simply boiled down to a given eating interval. Our mental and physical health is much more nuanced than that, but intermittent fasting can be one of several initiatives to become a better version of yourself.

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Podcasts

• https://www.hubermanlab.com/episode/dr-satchin-panda-intermittent-fasting-to-improve-health-cognition-and-longevity
• https://www.hubermanlab.com/episode/effects-of-fasting-and-time-restricted-eating-on-fat-loss-and-health