Health Benefits of Fasting: Splitting Fact From Fiction
By Maeve Hanan
Fasting is becoming increasingly popular as a way to boost health.
But it can be confusing to figure out how much of the hype is backed by evidence.
This article discusses the different types of fasting, including intermittent fasting, along with some of their main benefits.
What is Fasting?
Fasting is a period of time when little to no food is eaten.
People may choose to fast for health, religious or spiritual reasons.
The main types of fasting include:
- intermittent fasting (IF)
- water fasting
- liquid fasting
- juice fasting
- religious fasting
- fasting for a medical procedure.
There is some evidence that fasting was a natural part of life for our ancestors due to cycles of "feast or famine," which may affect how our body stores and uses energy today (1).
Summary: Fasting involves eating little or no food for a set amount of time, and may be done for health, religious or spiritual reasons.
Types of Fasting
Each type of fasting has its own restrictions for when and how often you should eat.
Intermittent fasting (IF) is a pattern of eating that involves switching between periods of fasting and non-fasting.
IF is often a more manageable approach to fasting that offers many of its same benefits.
There are different types of IF including:
- The 5:2 Diet involves eating no more than 600 calories per day for two days a week, while eating normally the other five days.
- The 6:1 Diet (also called Eat Stop Eat) involves fasting for 24 hours once per week, without changing your diet on the remaining 6 days.
- Alternate Day Fasting usually involves alternating between fasting for 24 hours, then eating normally for the next 24 hours on repeat.
- The 16:8 Diet (also called the Leangains Method) involves eating within an 8-hour window everyday, and fasting for the other 16 hours. For example, many people choose to skip breakfast and eat between 12pm and 8pm.
Religious or Spiritual Fasting
One perceived benefit of fasting for those with spiritual beliefs is to "cleanse the soul."
Most major religions promote periods of fasting, which often goes hand in hand with times of prayer.
Water fasting involves only consuming water, though some diets also allow black tea and coffee.
The length of water fasts can vary, but most last 24-72 hours. Some of the benefits of IF diets also apply to 24-hour water fasting since there's an overlap with the 6:1 IF diet.
For example, one study found that a 24-hour water fast increased total cholesterol (including HDL, the "good" cholesterol) and reduced triglyceride levels and weight. However, the study was small and only lasted two days (2).
Medically-supervised water fasting has also shown to slightly reduce blood pressure (3).
However, while water fasting may have some potential benefits, it can also be an extreme and unhealthy way to diet.
In fact, one study found that water fasting can lead to fatigue, nausea, headaches, raised blood pressure and even life-threatening cases of dehydration and low sodium levels (4).
Fasting for a Medical Procedure
Certain medical procedures require patients to fast beforehand.
This is to ensure that no unsafe regurgitation will occur under general anesthetic, and that images can be seen properly during a gastroscopy.
Summary: Intermittent fasting (IF) involves switching between periods of eating and fasting, while water fasting restricts all intake of food for a set period of time. Others choose to fast for religious or spiritual reasons. You may also be asked to fast before a medical procedure.
Health Benefits of Fasting
As you might expect, fasting can help you reduce your calorie intake because it limits the hours in a day that you can eat.
It can also help promote weight loss, which we'll discuss more below.
The "thrifty genotype theory" suggests that we've evolved to benefit from periods of fasting. This means fasting may affect our biochemistry and metabolism and reduce the risk of conditions such as type 2 diabetes (7).
Fasting has also been linked with reducing inflammation and damage caused by free radicals.
Summary: Fasting diets can help reduce calorie intake, promote healthy aging, reduce inflammation and reduce risk of conditions like type 2 diabetes.
Benefits of Intermittent Fasting (IF)
IF has become increasingly popular as it's a more manageable way to fast while still reaping many of its benefits.
Intermittent Fasting and Weight Loss
Studies have found specific weight loss benefits related to IF.
A trial from 2017 found that IF resulted in a similar amount of weight loss as traditional dieting (10).
Another study found that simply reducing the window of eating from 14 hours to 10-11 hours per day boosted weight loss (11).
Islamic fasting during Ramadan can also be described as a type of daily IF, since no food is eaten between sunrise and sunset everyday. This type of fasting amounts to an average intake of 1,220 calories per day and 1-2 kg weight loss, but most of this weight is usually regained within 2 weeks after Ramadan has ended (12, 13).
Similarly, studies among the Seventh-day Adventist population have found that having the largest meal of the day at breakfast time and eating fewer calories later in the day is associated with a healthier BMI level (14).
Intermittent Fasting May Reduce the Risk of Heart Disease, Diabetes and Depression
IF may also have a great effect on your physical and mental health.
Some studies have found that IF could help reduce the risk of heart disease since it's been shown to improve cholesterol levels, reduce damage from free radicals, and decrease blood pressure (15, 16, 17, 18).
IF diets can also reduce the risk of diabetes. It's been shown to improve insulin levels and insulin resistance to the same degree as traditional calorie restriction (19).
Practicing IF may also help people reduce symptoms of depression. One study found a significant reduction in anger, tension, confusion and low mood in a group of older men who were following an IF diet (22).
While many of these findings are promising, the evidence isn't very strong. More research is needed to better verify these potential benefits.
Intermittent Fasting and Aging
Animal studies have found that IF may promote autophagy, a process our body uses to recycle damaged parts of cells that may potentially be harmful. This in itself could potentially slow down aging (25, 26).
This is a very interesting topic, but at the moment we need more research to look into whether IF definitely promotes healthy aging in humans.
Summary: Intermittent fasting (IF) involves regular cycles of fasting and non-fasting. IF can be an easier type of fasting to follow and may promote weight loss and healthy aging, reduce the risk of type 2 diabetes and heart disease, and improve mood.
What Are the Health Risks of Fasting?
Risks related to fasting can range from headaches and lack of energy to patterns of disordered eating and more serious health issues.
Who Should Avoid Fasting?
Fasting is not recommended for people who need a regular supply of nutrients, such as:
- growing children
- pregnant or breastfeeding women
- those who are malnourished
- some people with: type 1 diabetes, cancer, liver disease, kidney disease, reflux or heartburn (29, 30, 31, 32, 33).
Fasting May Lead to Disordered Eating
Fasting in an extreme or unhealthy way can be a symptom of an eating disorder.
Therefore, those who have an active or previous eating disorder should avoid fasting.
Females can be more susceptible to this. For example, a study of teenage girls found that those who fasted were at a higher risk of developing bulimia and binge-eating behavior as compared to those who dieted in a more traditional way (34).
Fasting Risks For Women
Some women report negative side effects related to fasting diets including:
- missed periods
- binge eating
- changes in metabolism
- early-onset menopause.
However, not much research has looked into why these things can happen, but it might be related to female hormones.
Other Possible Risks
Prolonged fasting has also been associated with:
- increased cholesterol
- pancreas damage
- worsened insulin function (which increases the risk of diabetes)
- irregular heartbeat, headaches and fainting
- slight reductions in athletic performance, exercise ability and muscle mass (35, 36, 37, 38, 39, 40).
There are even some reported cases of death caused by prolonged fasting as a weight loss method (41).
In general, more studies in humans need to be performed before we can say whether IF is a safe and healthy approach in the long-run (42).
Summary: Fasting is not recommended for those who need a regular supply of nutrients for their health, including pregnant or breastfeeding women, or people with certain medical conditions. Possible side effects related to fasting include malnutrition, dehydration, disordered eating and even death in some cases. But serious risks are rare and usually related to prolonged fasting, not IF.
Should You Try Fasting?
Fasting involves having little or no food for a period of time.
Intermittent fasting involves switching between periods of eating and fasting, while water fasting restricts all food intake for a set period of time. People may also fast for religious or spiritual reasons, or in preparation for a medical procedure.
There is some evidence that fasting may help with weight loss and reducing the risk of type 2 diabetes and heart disease. This is mostly because fasting typically helps people reduce their calorie intake.
The benefits of fasting may also include a reduction in inflammation and damage caused by free radicals, improved mood and even promoting healthy aging.
However, more research is needed to confirm that fasting offers such benefits, and in a variety of populations.
This is because fasting doesn't seem to be suitable for everyone, including those who need a regular supply of nutrients for their health, like pregnant or breastfeeding women and people with certain medical conditions.
Fasting must be done with caution, as it can come with some serious health risks like malnutrition, dehydration or a development of disordered eating.
In general, if you're fasting to lose weight or improve your health, you may want to consider less risky—and way more pleasurable—ways of eating to boost your health.
You may wish to discover the best diet for your tastes and goals by playing this short game.
Reposted with permission from our media associate Diet vs Disease.
EcoWatch Daily Newsletter
By Zahida Sherman
Cooking has always intimidated me. As a child, I would anxiously peer into the kitchen as my mother prepared Christmas dinner for our family.
Falling in Love With Food All Over Again<p>Slowly, through my most intimate relationships with friends and partners, I began to see the beauty — and rewards — of cooking.</p><p>I got tired of giving in to defeat and always bringing chips or paper products to social gatherings. I started asking my mom to send me her Christmas and Thanksgiving recipes. I even volunteered to host Thanksgiving dinner at my place.</p><p>Each time I heard my loved ones sing the praises of the foods I prepared for them, I felt a tinge more confident that I could carry out our traditions my way.</p><p>In reaching out to other relatives for their favorite recipes, I learned that they had a little help of their own. They didn't rely solely on their ancestral cooking instincts. They turned to Black chefs for guidance.</p><p>These 7 cookbooks by Black chefs have inspired my family and fed us in nutrients, joy, and spiritual sustenance. They're also helping me overcome my personal fears of cooking.</p>
Get CookingWhether you're in recovery from cooking fears like me, or are just looking to expand your culinary confidence with dishes honoring Black heritage, these Black chefs are here to support you on your journey.Turn on some music, give yourself permission to make mistakes, and throw down for yourself or your loved ones. Glorious flavors await you.
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By Tara Lohan
The conclusion to decades of work to remove a dam on the Middle Fork Nooksack River east of Bellingham, Washington began with a bang yesterday as crews breached the dam with a carefully planned detonation. This explosive denouement is also a beginning.
The History<p>The Middle Fork Nooksack drains glacier-fed headwater streams that run off the icy summit of 10,778-foot Mt. Baker. The Middle Fork joins the North Fork and then the mainstem of the Nooksack River, which travels to Bellingham Bay and Puget Sound. The entire Nooksack watershed stretches 830 square miles across Washington and into British Columbia.</p>
A Plan Comes Together<p>The Middle Fork dam is not a pool dam built for water storage. Much of the time, water flows over the top until dam operators drop a floodgate to divert water to new locations. That water travels about 14 miles through tunnel and pipeline to Mirror Lake, then Anderson Creek, and to Lake Whatcom before finally being delivered to residents' taps.</p><p>Before removing the dam, engineers had to move the water intake 700 feet upstream and situate it at an elevation that still enabled city water withdrawals throughout the year, regardless of flow conditions.</p><p>They also needed to make sure that the rushing water didn't sweep up fish and accidentally send them through the water-supply system.</p><p>"The solution required a fairly complex design in the intake structure, including a fish exit pipe out of that structure to put fish back into the river in a way that meets current environmental permit standards," explains LaCroix.</p>
Project layout for the removal of the Middle Fork Nooksack diversion dam and rebuilding of water intake. City of Bellingham<p>Despite the cost and the work, she says, being able to continue to meet their municipal water obligations while opening up habitat for threatened species has been a win-win.</p><p>"I think there's a lot of benefits to having a dam removal versus fish passage — the main one being that you get a free-flowing river that can be a dynamic ecosystem and change over time," she says. "A static fish ladder just can't provide that same level of ecosystem benefit."</p>
Restoration Success<p>Despite local authorities' championing dam removal on the Middle Fork, the project has largely flown under the radar, overshadowed in the Pacific Northwest by heated discussions about a much larger potential project — removing <a href="https://www.seattletimes.com/seattle-news/feds-reject-removal-of-4-snake-river-dams-in-key-report/" target="_blank">four federal hydroelectric dams on the lower Snake River</a>, a major tributary of the Columbia River.</p><p>Proponents of dam removal there see it as the best chance for recovering threatened salmon populations, including Chinook, which could help starving Southern Resident killer whales. Those dams also provide irrigation water, barge navigation and hydropower, so there's been more pushback against removal efforts.</p><p>Previous dam removals around the country, however, have proved successful at aiding fish recovery and river restoration.</p><p>Most notably the 1999 demolition of <a href="https://therevelator.org/edwards-dam-removal/" target="_blank">Edwards Dam on Maine's Kennebec River</a> restored the annual run of alewives, a type of herring essential to the food web. The fish run has gone from zero to 5 million in the two decades since dam removal. Blueback herring, striped bass, sturgeon and shad have also extended their reach. And the resurgence has brought back osprey, bald eagles and other wildlife, too.</p><p>The overwhelming success of river restoration on the Kennebec helped to spur a nationwide dam removal movement that's now seen 1,200 dams come down since 1999. Last year a record <a href="https://www.americanrivers.org/conservation-resource/a-record-26-states-removed-dams-in-2019/" target="_blank">90 dams</a> were removed in 26 states, including <a href="https://therevelator.org/cleveland-forest-dam-removal/" target="_blank">20 dams in California's Cleveland National Forest</a>.</p>
Spider excavators remove on dam on San Juan Creek in California's Cleveland National Forest. Julie Donnell, USFS<p>The results have been seen in the Pacific Northwest, as well, which boasts the largest dam removal thus far in the country. In 2011 and 2014, the demolition of <a href="https://therevelator.org/elwha-dam-removal/" target="_blank">two dams</a> on Elwha River, which runs through Washington's Olympic National Park, opened up 70 miles of habitat that had been blocked for a century. Scientists have started seeing all five species of salmon native to the river coming back, particularly Chinook and coho. Bull trout, they've observed, have increased in size since the dams were removal.</p>
Benefits on the Middle Fork Nooksack<p>McEwan hopes to see a similar outcome on the Middle Fork.</p><p>Like the Elwha the Middle Fork Nooksack is a relatively pristine river with little development, and dam removal is expected to provide a big boost to fish. The additional miles of spawning habitat are important, but so is the temperature of that water.</p><p>The dam removal will open access to cold upstream waters, which are ideal for salmon and getting harder to come by as climate change warms waters and reduces mountain runoff.</p><p>"This is really great for the climate change resiliency for these species," says McEwan.</p><p>Steelhead will get back 45% of their historic habitat in the river, and scientists expect Chinook populations to increase in abundance by 31%.</p><p>That <em>could</em> help Southern Resident killer whales.</p><p>"When you get to the ocean, it's a little bit of a black box in terms of what you can model and say definitively is going to help, but more fish is better for orcas," McEwan says.</p><p>Upstream habitat will see benefits, too.</p><p>Oceangoing fish like salmon enrich their bodies with carbon and nitrogen while at sea. When they return to their natal rivers to spawn and die, the marine-derived nutrients they carry back upriver become important food and fertilizer for both riverine and terrestrial ecosystems — aiding everything from trees to birds to bears.</p><p>"Once the fish start making their way back, it will start changing the whole ecological system," says Delgado.</p><p><span></span>But any ecological benefit from salmon restoration, either in the ocean or the upper watershed, won't be immediate.<br></p><p>"The population of salmon on the Middle Fork is so low that we expect it's going to take quite a while to rebound," she says. "But the big picture is that what's good for salmon is good for the region — our history and our destiny are intricately intertwined."</p><p>After decades of work, that process of restoration has finally begun.</p>
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By Katie Howell
A new tool called The Food Systems Dashboard aims to save decision makers time and energy by painting a complete picture of a country's food system. Created by the Johns Hopkins' Alliance for a Healthier World, the Global Alliance for Improved Nutrition (GAIN), and the U.N. Food and Agriculture Organization (FAO), the Dashboard compiles food systems data from over 35 sources and offers it as a public good.
By Manuela Callari
It can grow to a maximum of six inches (16 centimeters), change color depending on mood and habitat, and, like all seahorses, the White's seahorse male gestates its young. But this tiny snouted fish is under threat.
Building an Ocean Seahorse Destination<p>Seahorses are found in tropical and temperate coastal water worldwide, but are most abundant around Australia, China and the Philippines. </p><p>Trade in the tiny creatures is strictly regulated because of their use in traditional medicine, aquariums and their sale as dried curios. But because they are poor swimmers and cannot easily move elsewhere, habitat loss is a particular threat for these curious animals. </p><p>Seahorses wrap their tails around seagrass and corals to avoid being carried away on currents. They use the habitat to spawn and hide from predators such as crabs, while also feeding on riches of plankton and small crustaceans living in the reef.</p><p><span></span>Where corals aren't available, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.1217" target="_blank">scientists</a> found seahorses taking up residence in fishing nets and old crab traps abandoned at the bottom of the ocean. </p>
Mixing With the Locals<p>Baby seahorse mortality is high in the wild because they are easily caught, so those bred in the protected environment of the aquarium weren't ready to be released into the wild until early May.</p><p>The team released 90 new arrivals into Sydney Harbor, placing some directly into the purpose-built hotels, and others onto a net that wild seahorses had already settled on.</p><p>Before setting them free, the researchers marked each young seahorse with a fluorescent tag with unique IDs inserted just beneath the skin to track how they get on in the different environments. </p><p>"The most exciting part was being able to put these animals into the wild and then go back a month later and still see them surviving and growing," said McCracken. </p><p>The seahorses will be old enough to mate and reproduce around October or November 2020. And researchers hope that by then, they will be able to breed with the wild population. </p>
Building a Global Seahorse Hotel Chain<p>With seahorses everywhere facing the loss of their coral reef homes, similar projects have sprung up in places like Greece and South Africa, home to the world's most endangered seahorse, the Knysna seahorse. </p><p>"The endangered South African seahorse is benefiting from something quite similar, even though it wasn't intentional," said Peter Teske, professor at the Department of Zoology, University of Johannesburg.</p><p>In the South African <a href="https://www.researchgate.net/publication/322649251_An_endangered_seahorse_selectively_chooses_an_artificial_structure" target="_blank">case</a>, seahorses have bedded down in "Reno mattresses" — wire cages filled with rocks — that were used to build a new marina. Researchers from NGO Knysna Basin Project found the structures acted as a refuge for the animals.<span></span></p><p><span></span>While Teske describes the seahorse hotels as "a positive news story" and a great way to create public awareness of conservation, he added that establishing artificial habitats in some areas will only prevent the extinction of local populations.</p><p>"For a complete recovery, it is necessary to give the natural habitat a chance to regenerate," said the seahorse expert. </p>
Underwater Mascot<p>In Australia, the researchers hope the project could provide an opportunity to raise awareness not only of the plight of the Sydney seahorses but the other animals with which it shares its ocean habitat.</p><p>The waters around Sydney and the east coast are rich in biodiversity and include several threatened species like the weedy seadragon — a relative of the seahorse — and the grey nurse shark. Like the seahorse, they're also under pressure from pollution, ocean traffic and habitat loss through storms and coastal construction. </p><p>"It's a good thing to get people's support and interest. The seahorses are a useful vehicle to get people concerned if the harbor is in trouble," said David Booth, professor of marine ecology at the University of Technology Sydney who is also working on the project. </p><p>The hotels have become an attraction for divers hoping to catch a glimpse of these small but near mythical creatures. </p><p>"Everyone loves seahorses," added Booth, "they are so popular." </p>
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