Let’s face it - no one likes the idea of getting old. This, combined with the global trend of aging populations, has given rise to a new era of longevity research. Increasingly, people are looking for strategies to prolong their life span and extend their healthy years.
Nutrition plays a key role in chronic disease prevention, and while there are many proposed dietary strategies for longevity, intermittent fasting has become an increasingly popular approach. But does intermittent fasting (IF) really help you live longer? Before diving into more details, let’s get a better understanding of intermittent fasting and how it works.
What is intermittent fasting?
The key characteristic of IF is cycling between periods of fasting and eating for specific times throughout the day or week. Unlike other popular diets that have strict food and nutrient requirements, time is the only real restriction with IF — which many people seem to like. Essentially, you can eat what you want on IF, providing that you consume food within your ‘eating window’.
There are several approaches to IF that mostly vary by length of fast:
Time restricted feeding (TRF): Commonly referred to as the 16:8 Method, time-restricted feeding typically involves limiting your daily eating window to 8 hours followed by a 16-hour overnight fast. This method is one of the most standard approaches, and one that many people find easiest to start with.
Alternate day fasting: With alternate day fasting, you fast every other day, typically eating freely on the non-fasting days, and consuming about 25% of your daily calorie needs on fasting days.
5:2 diet: This strategy involves restricting energy intake to 500-600 calories two days a week and normal eating the other five days [
1].
Though intermittent fasting does not dictate any specific dietary recommendations, limiting your intake to a specific eating window often reduces your caloric intake which can result in weight loss for some.
Learn more about the pros and cons of intermittent fasting for
runners and
cyclists.
What happens when you fast?
Intermittent fasting influences hormone levels, cell repair, metabolic rate, and gene expression. The effects of intermittent fasting are far-reaching, and many of them are directly tied to living a longer, healthier life.
Fasting has been shown to enhance the secretion of growth hormone (GH), which can be beneficial for both fat loss and muscle gain [
2]. IF activates autophagy (a process where new healthy cells regenerate), and it also produces profound metabolic changes (where it switches from burning glucose to fatty acids) [
1].
Additionally, fasting has been proposed to be a method of increasing longevity via these physiological adaptations, as well as via increased protein and DNA stability, insulin sensitivity, and changes in the expression of genes related to aging and disease prevention [
3]. All these processes are beneficial for human health and can promote longevity and healthy aging.
Read more about what happens during different fasting intervals
here.
Intermittent fasting and longevity
Potential benefits of IF include weight loss, improved heart health, blood sugar control, neuroprotection and protection against some forms of cancer, however, research on IF is still in its infancy for many indications.
Weight loss: Even without intentional calorie reduction, one study showed that 8-hour time-restricted-feeding produced weight loss in obese adults [
4].
Cardiovascular health: Some studies have shown the benefits IF can have on several markers of heart health, including decreases in resting heart rate, circulating insulin, glucose, and homocysteine, total cholesterol, LDL cholesterol, and triglyceride levels, as well as reduced blood pressure [
5,
6].
Diabetes: Fasting can help control blood sugar levels and increase insulin sensitivity, both of which are key metrics in managing and preventing type 2 diabetes [
5,
6].
Neurological conditions: Though there has not been much research done in humans yet, animal models show promising evidence for the positive effect IF may have on cognitive ability, with potential neuroprotective and regenerative effects [
1].
Cancer: Intermittent fasting shows great promise in both the prevention and treatment of certain cancers. Animal studies have shown that periodic fasting can be as effective as chemotherapy in several cancers and can even protect non-cancer cells from the effects of chemo [
5].
All-cause mortality: Emerging evidence suggests that IF can reduce all-cause mortality. One study found that those who routinely fasted had a 45% lower mortality rate than those who did not fast regularly [
8].
Who shouldn’t fast?
Although intermittent fasting can provide health benefits for many people, this method may not be for everyone. Fasting for long periods of time can cause headaches, lightheadedness, mood changes, constipation, fatigue, and irritability if not approached correctly. Additionally, IF can lead to inadequate nutrition intake (which can lead to deficiencies), reproductive problems, and reduced sports performance. This eating approach can be hard to manage in social situations, and it may mask disordered eating.
IF is not recommended for:
If you are uncertain whether intermittent fasting is a good idea for you, consult a Registered Dietitian or speak with your healthcare provider.
Summary
Intermittent fasting is a unique approach to eating that does not dictate what you eat, but when you eat. There are several different approaches to IF, including TRF and alternate day fasting. Intermittent fasting appears to impact various physiological processes including hormone function, cellular regeneration, and metabolism, all of which have effects on your health. The potential benefits from IF include weight loss, improved cardiovascular health, and lower risk of developing chronic diseases, and thereby may increase longevity and overall wellbeing. Intermittent fasting is not for everyone, so it’s important to understand the risks and benefits before giving it a try.
Disclaimer: The text, images, videos, and other media on this page are provided for informational purposes only and are not intended to treat, diagnose, or replace personalized medical care.
