Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting.
Numerous studies show that it can have powerful benefits for your body and brain.
Here are 10 evidence-based health benefits of intermittent fasting.
1. Intermittent Fasting Changes The Function of Cells, Genes and Hormones
When you don't eat for a while, several things happen in your body.
For example, your body initiates important cellular repair processes and changes hormone levels to make stored body fat more accessible.
Here are some of the changes that occur in your body during fasting:
- Insulin levels: Blood levels of insulin drop significantly, which facilitates fat burning (1).
- Human growth hormone: The blood levels of growth hormone may increase as much as 5-fold (2, 3). Higher levels of this hormone facilitate fat burning and muscle gain, and have numerous other benefits (4, 5).
- Cellular repair: The body induces important cellular repair processes, such as removing waste material from cells (6).
- Gene expression: There are beneficial changes in several genes and molecules related to longevity and protection against disease (7, 8).
2. Intermittent Fasting Can Help You Lose Weight and Belly Fat
Many of those who try intermittent fasting are doing it in order to lose weight (9).
Generally speaking, intermittent fasting will make you eat fewer meals.
Unless if you compensate by eating much more during the other meals, you will end up taking in fewer calories.
Additionally, intermittent fasting enhances hormone function to facilitate weight loss.
Lower insulin levels, higher growth hormone levels and increased amounts of norepinephrine (noradrenaline) all increase the breakdown of body fat and facilitate its use for energy.
For this reason, short-term fasting actually -increases- your metabolic rate by 3.6-14 percent, helping you burn even more calories (10, 11).
In other words, intermittent fasting works on both sides of the calorie equation. It boosts your metabolic rate (increases calories out) and reduces the amount of food you eat (reduces calories in).
According to a 2014 review of the scientific literature, intermittent fasting can cause weight loss of 3-8 percent over 3-24 weeks (12). This is a huge amount.
The people also lost 4-7 percent of their waist circumference, which indicates that they lost lots of belly fat, the harmful fat in the abdominal cavity that causes disease.
One review study also showed that intermittent fasting caused less muscle loss than continuous calorie restriction (13).
All things considered, intermittent fasting can be an incredibly powerful weight loss tool. More details here: How Intermittent Fasting Can Help You Lose Weight.
Bottom Line: Intermittent fasting helps you eat fewer calories, while boosting metabolism slightly. It is a very effective tool to lose weight and belly fat.
3. Intermittent Fasting Can Reduce Insulin Resistance, Lowering Your Risk of Type 2 Diabetes
Type 2 diabetes has become incredibly common in recent decades.
Its main feature is high blood sugar levels in the context of insulin resistance.
Anything that reduces insulin resistance should help lower blood sugar levels and protect against type 2 diabetes.
Interestingly, intermittent fasting has been shown to have major benefits for insulin resistance and lead to an impressive reduction in blood sugar levels (12).
In human studies on intermittent fasting, fasting blood sugar has been reduced by 3-6%, while fasting insulin has been reduced by 20-31 percent (12).
One study in diabetic rats also showed that intermittent fasting protected against kidney damage, one of the most severe complications of diabetes (13).
What this implies, is that intermittent fasting may be highly protective for people who are at risk of developing type 2 diabetes.
However, there may be some differences between genders. One study in women showed that blood sugar control actually worsened after a 22-day long intermittent fasting protocol (14).
Bottom Line: Intermittent fasting can reduce insulin resistance and lower blood sugar levels, at least in men.
4. Intermittent Fasting Can Reduce Oxidative Stress and Inflammation in The Body
Oxidative stress is one of the steps towards aging and many chronic diseases (14).
It involves unstable molecules called free radicals, which react with other important molecules (like protein and DNA) and damage them (15).
Several studies show that intermittent fasting may enhance the body's resistance to oxidative stress (16, 17).
Additionally, studies show that intermittent fasting can help fight inflammation, another key driver of all sorts of common diseases (17, 18, 19)
Bottom Line: Studies show that intermittent fasting can reduce oxidative damage and inflammation in the body. This should have benefits against aging and development of numerous diseases.
5. Intermittent Fasting May be Beneficial For Heart Health
Heart disease is currently the world's biggest killer (20).
It is known that various health markers (so-called “risk factors") are associated with either an increased or decreased risk of heart disease.
Intermittent fasting has been shown to improve numerous different risk factors, including blood pressure, total and LDL cholesterol, blood triglycerides, inflammatory markers and blood sugar levels (12, 21, 22, 23)
However, a lot of this is based on animal studies. The effects on heart health need to be studied a lot further in humans before recommendations can be made.
Bottom Line: Studies show that intermittent fasting can improve numerous risk factors for heart disease such as blood pressure, cholesterol levels, triglycerides and inflammatory markers.
6. Intermittent Fasting Induces Various Cellular Repair Processes
When we fast, the cells in the body initiate a cellular “waste removal" process called autophagy (7, 24).
This involves the cells breaking down and metabolizing broken and dysfunctional proteins that build up inside cells over time.
Increased autophagy may provide protection against several diseases, including cancer and Alzheimer's disease (25, 26).
Bottom Line: Fasting triggers a metabolic pathway called autophagy, which removes waste material from cells.
7. Intermittent Fasting May Help Prevent Cancer
Cancer is a terrible disease, characterized by uncontrolled growth of cells.
Fasting has been shown to have several beneficial effects on metabolism that may lead to reduced risk of cancer.
Although human studies are needed, promising evidence from animal studies indicates that intermittent fasting may help prevent cancer (27, 28, 29, 30).
There is also some evidence on human cancer patients, showing that fasting reduced various side effects of chemotherapy (31).
Bottom Line: Intermittent fasting has been shown to help prevent cancer in animal studies. One paper in humans showed that it can reduce side effects caused by chemotherapy.
8. Intermittent Fasting is Good For Your Brain
What is good for the body is often good for the brain as well.
Intermittent fasting improves various metabolic features known to be important for brain health.
This includes reduced oxidative stress, reduced inflammation and a reduction in blood sugar levels and insulin resistance.
Several studies in rats have shown that intermittent fasting may increase the growth of new nerve cells, which should have benefits for brain function (32, 33).
It also increases levels of a brain hormone called brain-derived neurotrophic factor (BDNF) (32, 34, 35), a deficiency of which has been implicated in depression and various other brain problems (36).
Animal studies have also shown that intermittent fasting protects against brain damage due to strokes (37).
Bottom Line: Intermittent fasting may have important benefits for brain health. It may increase growth of new neurons and protect the brain from damage.
9. Intermittent Fasting May Help Prevent Alzheimer's Disease
Alzheimer's disease is the world's most common neurodegenerative disease.
There is no cure available for Alzheimer's, so preventing it from showing up in the first place is critical.
A study in rats shows that intermittent fasting may delay the onset of Alzheimer's disease or reduce its severity (38).
In a series of case reports, a lifestyle intervention that included daily short-term fasts was able to significantly improve Alzheimer's symptoms in 9 out of 10 patients (39).
Animal studies also suggest that fasting may protect against other neurodegenerative diseases, including Parkinson's and Huntington's disease (40, 41).
However, more research in humans is needed.
10. Intermittent Fasting May Extend Your Lifespan, Helping You Live Longer
One of the most exciting applications of intermittent fasting may be its ability to extend lifespan.
Studies in rats have shown that intermittent fasting extends lifespan in a similar way as continuous calorie restriction (42, 43).
In some of these studies, the effects were quite dramatic. In one of them, rats that fasted every other day lived 83 percent longer than rats who weren't fasted (44).
Although this is far from being proven in humans, intermittent fasting has become very popular among the anti-aging crowd.
Given the known benefits for metabolism and all sorts of health markers, it makes sense that intermittent fasting could help you live a longer and healthier life.
This article was reposted from our media associate Authority Nutrition.
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In a new study, my colleagues Anisha Patel, Francesca Weaks and I estimate that approximately 61.4 million people in the U.S. did not drink their tap water as of 2017-2018. Our research, which was released in preprint format on April 8, 2021, and has not yet been peer reviewed, found that this number has grown sharply in the past several years.
Other research has shown that about 2 million Americans don't have access to clean water. Taking that into account, our findings suggest that about 59 million people have tap water access from either their municipality or private wells or cisterns, but don't drink it. While some may have contaminated water, others may be avoiding water that's actually safe.
Water insecurity is an underrecognized but growing problem in the U.S. Tap water distrust is part of the problem. And it's critical to understand what drives it, because people who don't trust their tap water shift to more expensive and often less healthy options, like bottled water or sugary drinks.
I'm a human biologist and have studied water and health for the past decade in places as diverse as Lowland Bolivia and northern Kenya. Now I run the Water, Health, and Nutrition Laboratory at Pennsylvania State University. To understand water issues, I talk to people and use large datasets to see whether a problem is unique or widespread, and stable or growing.
An Epidemic of Distrust
According to our research, there's a growing epidemic of tap water distrust and disuse in the U.S. In a 2020 study, anthropologist Sera Young and I found that tap water avoidance was declining before the Flint water crisis that began in 2014. In 2015-2016, however, it started to increase again for children.
Our new study found that in 2017-2018, the number of Americans who didn't drink tap water increased at an alarmingly high rate, particularly for Black and Hispanic adults and children. Since 2013-2014 – just before the Flint water crisis began – the prevalence of adults who do not drink their tap water has increased by 40%. Among children, not consuming tap has risen by 63%.
To calculate this change, we used data from the National Health and Nutrition Examination Survey, a nationally representative survey that releases data in two-year cycles. Sampling weights that use demographic characteristics ensure that the people being sampled are representative of the broader U.S. population.
Racial Disparities in Tap Water Consumption
Communities of color have long experienced environmental injustice across the U.S. Black, Hispanic and Native American residents are more likely to live in environmentally disadvantaged neighborhoods, with exposure to water that violates quality standards.
Our findings reflect these experiences. We calculated that Black and Hispanic children and adults are two to three times more likely to report not drinking their tap water than members of white households. In 2017-2018, roughly 3 out of 10 Black adults and children and nearly 4 of 10 Hispanic adults and children didn't drink their tap water. Approximately 2 of 10 Asian Americans didn't drink from their tap, while only 1 of 10 white Americans didn't drink their tap water.
When children don't drink any water on a given day, research shows that they consume twice as many calories from sugary drinks as children who drink water. Higher sugary drink consumption increases risk of cavities, obesity and cardiometabolic diseases. Drinking tap water provides fluoride, which lowers the risk of cavities. Relying on water alternatives is also much more expensive than drinking tap water.
A4: Choosing to drink fluoridated tap water over sugar-sweetened beverages to quench thirst is vital to protecting… https://t.co/3tm8wuWjeZ— Oral Health Watch (@Oral Health Watch)1600795750.0
What Erodes Trust
News reports – particularly high-visibility events like advisories to boil water – lead people to distrust their tap water even after the problem is fixed. For example, a 2019 study showed that water quality violations across the U.S. between 2006 and 2015 led to increases in bottled water purchases in affected counties as a way to avoid tap water, and purchase rates remained elevated after the violation.
The Flint water crisis drew national attention to water insecurity, even though state and federal regulators were slow to respond to residents' complaints there. Soon afterward, lead contamination was found in the water supply of Newark, New Jersey; the city is currently replacing all lead service lines under a legal settlement. Elsewhere, media outlets and advocacy groups have reported finding tap water samples contaminated with industrial chemicals, lead, arsenic and other contaminants.
Many other factors can cause people to distrust their water supply, including smell, taste and appearance, as well as lower income levels. Location is also an issue: Older U.S. cities with aging infrastructure are more prone to water shutoffs and water quality problems.
It's important not to blame people for distrusting what comes out of their tap, because those fears are rooted in history. In my view, addressing water insecurity requires a two-part strategy: ensuring that everyone has access to clean water, and increasing trust so people who have safe water will use it.
Chart: The Conversation / CC BY-ND. Source: AWWA / Morning Consult. Get the data
Building Confidence
As part of his proposed infrastructure plan, President Joe Biden is asking Congress for $111 billion to improve water delivery systems, replace lead pipelines and tackle other contaminants. The plan also proposes improvements for small water systems and underserved communities.
These are critical steps to rebuild trust. Yet, in my view, the U.S. Environmental Protection Agency should also provide better public education about water quality testing and targeted interventions for vulnerable populations, such as children and underserved communities. Initiatives to simplify and improve water quality reports can help people understand what's in their water and what they can do if they think something is wrong with it.
Chart: The Conversation / CC BY-ND. Source: AWWA / Morning Consult. Get the data
Who delivers those messages is important. In areas like Flint, where former government officials have been indicted on charges including negligence and perjury in connection with the water crisis, the government's word alone won't rebuild trust. Instead, community members can fill this critical role.
Another priority is the 13%-15% of Americans who rely on private well water, which is not regulated under the Safe Drinking Water Act. These households are responsible for their own water quality testing. Public funding would help them test it regularly and address any problems.
Public distrust of tap water in the U.S. reflects decades of policies that have reduced access to reliable, safe drinking water in communities of color. Fixing water lines is important, but so is giving people confidence to turn on the tap.
Asher Rosinger is an assistant professor of biobehavioral health, anthropology, and demography and director of the Water, Health, and Nutrition Laboratory at Penn State University.
Disclosure statement: Asher Rosinger receives funding from the National Science Foundation on an unrelated project. This work was supported by the Ann Atherton Hertzler Early Career Professorship funds, and the Penn State Population Research Institute (NICHD P2CHD041025). The funders had no role in the research or interpretation of results.
Reposted with permission from The Conversation.
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