Intermittent-fasting: What, how and why

Intermittent fasting (IF) is the latest buzzword among those concerned with health, fitness and overall functioning. It is currently one of the world’s most popular health trends.

People are using it to lose weight, improve their health and simplify their lifestyles. But not eating for periods of time surely can’t be beneficial to your health, you may ask.

Healthline has provided all the answers on intermittent fasting that you’re seeking.

History of fasting

Fasting has been a practice throughout human evolution. Ancient hunter-gatherers didn’t have supermarkets, refrigerators or food available all the time. As a result, they evolved to be able to function without food for extended periods of time. Due to this, fasting from time to time is more natural than always eating 3–4 (usually more) meals a day.

Fasting is also often done for religious or spiritual reasons, including in Islam, Christianity, Judaism and Buddhism.

What is intermittent fasting?

This is an eating pattern that cycles between periods of fasting (not eating) and feasting (eating). What’s unusual here, is that IF doesn’t specify which foods you should eat; the benefits rather lie in when you should eat.

Common IF methods involve daily 16-hour fasts or fasting for 24 hours, twice a week.

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Popular IF methods

The 16/8 method: Also called the Leangains protocol, it involves skipping breakfast and restricting your daily eating period to 8 hours, such as 10am–6pm. Then you fast for 16 hours in between. (This time flies by if you fast overnight).

Eat-Stop-Eat: This involves fasting for 24 hours, once or twice a week. Possibly by not eating from dinner one day until dinner the next day.

The 5:2 diet: With this method, you consume only 500–600 calories on two non-consecutive days of the week, but eat normally the other 5 days.

Many people find the 16/8 method is the simplest, most sustainable and easiest to stick to. It’s also the most popular.

Affects on a cellular and molecular level

When you fast, several things happen in your body on the cellular and molecular level. For example, your body adjusts hormone levels to make stored body fat more accessible. Your cells also initiate important repair processes and change the expression of genes.

Here are some changes that occur in your body when you fast:

Human Growth Hormone (HGH): The levels of growth hormone skyrocket, increasing as much as 5-fold. This has benefits for fat loss and muscle gain.

Insulin: Insulin sensitivity improves and levels of insulin drop dramatically. Lower insulin levels make stored body fat more accessible.

Cellular repair: When fasted, your cells initiate cellular repair processes. This includes autophagy, where cells digest and remove old and dysfunctional proteins that build up inside cells.

Gene expression: There are changes in the function of genes related to longevity and protection against disease.

These changes in hormone levels, cell function and gene expression are responsible for the following health benefits of intermittent fasting.

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Benefits of IF

Weight loss: Intermittent fasting can help you lose weight and belly fat, without having to consciously restrict calories.

Insulin resistance: Intermittent fasting can reduce insulin resistance, lowering blood sugar by 3–6 per cent and fasting insulin levels by 20–31 per cent, which should protect against type 2 diabetes.

Inflammation: Some studies show reductions in markers of inflammation, a key driver of many chronic diseases.

Heart health: Intermittent fasting may reduce ‘bad’ LDL cholesterol, blood triglycerides, inflammatory markers, blood sugar and insulin resistance — all risk factors for heart disease.

Cancer: Animal studies suggest that intermittent fasting may prevent cancer.

Brain health: Intermittent fasting increases the brain hormone BDNF and may aid the growth of new nerve cells. It may also protect against Alzheimer’s disease.

Anti-aging: Studies have shown that intermittent fasting can extend lifespan in certain animals.

Healthline reminded that research is still in its early stages. Many of the studies were small, short-term or conducted in animals. Many questions have yet to be answered in higher quality human studies.

Who should be careful or avoid it?

Those who are underweight or have a history of eating disorders should not fast. There is also some evidence that intermittent fasting may be harmful to some women.

Safety and side effects

Hunger is the main side effect of IF. You may also feel weak and your brain may not perform as well as you’re used to. This may only be temporary, as it can take some time for your body to adapt to the new meal schedule. If you have a medical condition, you should consult with your doctor before trying IF.

This is particularly important if you:

• Have diabetes.
• Have problems with blood sugar regulation.
• Have low blood pressure.
• Take medications.
• Are underweight.
• Have a history of eating disorders.
• Are a woman who is trying to conceive.
• Are a woman with a history of amenorrhea.
• Are pregnant or breastfeeding.

All that being said, intermittent fasting has an outstanding safety profile. There is nothing dangerous about not eating for a while if you’re healthy and well-nourished overall.

There is no need to follow a structured intermittent fasting plan to derive at least some of the benefits. Experiment with the different approaches and find something that you enjoy and fits your schedule.

Check out Healthline’s original article for further information on IF, together with useful questions and answers to intermittent fasting.