Does Intermittent Fasting Boost Your Metabolism?
By Helen West
Intermittent fasting is an eating pattern that involves periods of food restriction (fasting) followed by normal eating. This pattern of eating could help you lose weight, reduce your risk of disease and increase your lifespan (1, 2).
Intermittent Fasting Is Highly Effective for Weight Loss
In fact, a 2014 review found that intermittent fasting could help people lose an impressive 3–8 percent of their body weight in 3–24 weeks (9).
Moreover, a recent review concluded that in overweight and obese people, intermittent fasting may be a better approach to weight loss than very-low-calorie diets (10).
If you are interested in trying intermittent fasting, you can read more about it in this detailed guide for beginners.
Bottom Line: Intermittent fasting is a powerful weight loss tool. It can also improve your metabolism and metabolic health.
Intermittent Fasting Increases Several Fat Burning Hormones
Hormones are chemicals that act as messengers. They travel through your body to coordinate complicated functions such as growth and metabolism.
They also play an important role in the regulation of your weight. This is because they have a strong influence on your appetite, the number of calories you eat and how much fat you store or burn (14).
Intermittent fasting has been linked to improvements in the balance of some fat burning hormones. This could make it a helpful tool for weight management.
Insulin is one of the main hormones involved in fat metabolism. It tells your body to store fat and also stops your body from breaking fat down.
Having chronically high levels of insulin can make it much harder to lose weight. High levels of insulin have also been linked to diseases like obesity, type 2 diabetes, heart disease and cancer (9, 15, 16).
In fact, this eating style could reduce fasting insulin levels by 20–31 percent (9).
Human Growth Hormone
Increases in blood levels of human growth hormone not only promote fat burning, but they also preserve muscle mass and have other benefits (24).
However, women don't always experience the same benefits from fasting as men do and it's not currently clear if women will see the same rise in human growth hormone.
It has a variety of other effects on your body, one of which is telling your body's fat cells to release fatty acids.
Increases in norepinephrine generally lead to larger amounts of fat being available for your body to burn.
Bottom Line: Fasting can help decrease insulin levels and boost blood levels of human growth hormone and norepinephrine. These changes can help you burn fat more easily and help you lose weight.
Short-Term Fasts Boost Metabolism by up to 14 Percent
Many people believe that skipping meals will cause your body to adapt by lowering its metabolic rate to save energy.
One study in 11 healthy men found that a 3-day fast actually increased their metabolism by an impressive 14 percent (26).
This increase is thought to be due to the rise in the hormone norepinephrine, which promotes fat burning.
Bottom Line: Fasting for short periods can slightly boost your metabolism. However, fasting for long periods may have the opposite effect.
Intermittent Fasting Decreases Metabolism Less Than Continuous Calorie Restriction
When you lose weight, your metabolic rate goes down. Part of this is because losing weight causes muscle loss and muscle tissue burns calories around the clock.
However, the decrease in metabolic rate seen with weight loss can't always be explained by the loss of muscle mass alone (32).
Severe calorie restriction over a long period can cause your metabolic rate to drop, as your body enters so-called starvation mode (or "adaptive thermogenesis"). Your body does this to conserve energy as a natural defense against starvation (33, 34).
This has been demonstrated dramatically in a study of people who lost large amounts of weight while participating in the Biggest Loser show on TV.
Participants followed a calorie-restricted diet and intense exercise regimen to lose large amounts of weight (35).
The study found that six years later, most of them had regained nearly all of the weight they had lost. However, their metabolic rates had not gone back up and remained around 500 calories lower than you would expect for their body size.
Other studies investigating the effects of calorie restriction on weight loss have found similar results. The drop in metabolism due to weight loss can amount to hundreds of calories per day (36, 37).
This confirms that "starvation mode" is real and can partly explain why many people who lose weight end up regaining it.
Given the short-term effects of fasting on hormones, it's possible that intermittent fasting may reduce the drop in metabolic rate caused by long-term calorie restriction.
One small study showed that losing weight on an alternate-day fasting diet did not reduce metabolism over 22 days (17).
However, currently there is no quality research available looking at the long-term effects of intermittent fasting diets on metabolic rate.
Bottom Line: One small study suggests that intermittent fasting may reduce the drop in metabolic rate that's associated with weight loss. More research is needed.
Intermittent Fasting Helps You Hold on to Muscle Mass
Unfortunately, most people lose both fat and muscle when they lose weight (41).
In particular, the increase in human growth hormone observed during fasting could help preserve muscle mass, even if you're losing weight (44).
A 2011 review found that intermittent fasting was more effective at retaining muscle during weight loss than a traditional, low-calorie diet (45).
One recent study found no difference between the lean body mass of people who were fasting and people on continuous calorie restriction after eight weeks. However, at 24 weeks, those in the fasting group had lost less lean body mass (6).
Larger and longer studies are needed to find out if intermittent fasting is more effective at preserving lean body mass.
Bottom Line: Intermittent fasting may help reduce the amount of muscle you lose when you lose weight. However, the research is mixed.
Although research has shown some promising findings, the effects of intermittent fasting on metabolism are still being investigated (3).
If this is true, then intermittent fasting has several important weight loss advantages over diets based on continuous calorie restriction.
At the end of the day, intermittent fasting can be a highly effective weight loss tool for many people.
Reposted with permission from our media associate Authority Nutrition.
By Daisy Simmons
1. Stay Informed<p>A first order of business in pet evacuation planning is to understand and be ready for the possible threats in your area. Visit <a href="https://www.ready.gov/be-informed" target="_blank">Ready.gov</a> to learn more about preparing for potential disasters such as floods, hurricanes, and wildfires. Then pay attention to related updates by tuning <a href="http://www.weather.gov/nwr/" target="_blank">NOAA Weather Radio</a> to your local emergency station or using the <a href="https://www.fema.gov/mobile-app" target="_blank">FEMA app</a> to get National Weather Service alerts.</p>
2. Ensure Your Pet is Easily Identifiable<p><span>Household pets, including indoor cats, should wear collars with ID tags that have your mobile phone number. </span><a href="https://www.avma.org/microchipping-animals-faq" target="_blank" rel="noopener noreferrer">Microchipping</a><span> your pets will also improve your chances of reunion should you become separated. Be sure to add an emergency contact for friends or relatives outside your immediate area.</span></p><p>Additionally, use <a href="https://secure.aspca.org/take-action/order-your-pet-safety-pack" target="_blank" rel="noopener noreferrer">'animals inside' door/window stickers</a> to show rescue workers how many pets live there. (If you evacuate with your pets, quickly write "Evacuated" on the sticker so first responders don't waste time searching for them.)</p>
3. Make a Pet Evacuation Plan<p> "No family disaster plan is complete without including your pets and all of your animals," says veterinarian Heather Case in <a href="https://www.youtube.com/watch?v=Q9NRJkFKAm4" target="_blank">a video</a> produced by the American Veterinary Medical Association.</p><p>It's important to determine where to take your pet in the event of an emergency.</p><p>Red Cross shelters and many other emergency shelters allow only service animals. Ask your vet, local animal shelters, and emergency management officials for information on local and regional animal sheltering options.</p><p>For those with access to the rare shelter that allows pets, CDC offers <a href="https://www.cdc.gov/healthypets/emergencies/pets-in-evacuation-centers.html" target="_blank">tips on what to expect</a> there, including potential health risks and hygiene best practices.</p><p>Beyond that, talk with family or friends outside the evacuation area about potentially hosting you and/or your pet if you're comfortable doing so. Search for pet-friendly hotel or boarding options along key evacuation routes.</p><p>If you have exotic pets or a mix of large and small animals, you may need to identify multiple locations to shelter them.</p><p>For other household pets like hamsters, snakes, and fish, the SPCA recommends that if they normally live in a cage, they should be transported in that cage. If the enclosure is too big to transport, however, transfer them to a smaller container temporarily. (More on that <a href="https://www.spcai.org/take-action/emergency-preparedness/evacuation-how-to-be-pet-prepared" target="_blank" rel="noopener noreferrer">here</a>.)</p><p>For any pet, a key step is to establish who in your household will be the point person for gathering up pets and bringing their supplies. Keep in mind that you may not be home when disaster strikes, so come up with a Plan B. For example, you might form a buddy system with neighbors with pets, or coordinate with a trusted pet sitter.</p>
4. Prepare a Pet Evacuation Kit<p>Like the emergency preparedness kit you'd prepare for humans, assemble basic survival items for your pets in a sturdy, easy-to-grab container. Items should include:</p><ul><li>Water, food, and medicine to last a week or two;</li><li>Water, food bowls, and a can opener if packing wet food;</li><li>Litter supplies for cats (a shoebox lined with a plastic bag and litter may work);</li><li>Leashes, harnesses, or vehicle restraints if applicable;</li><li>A <a href="https://www.avma.org/resources/pet-owners/emergencycare/pet-first-aid-supplies-checklist" target="_blank">pet first aid kit</a>;</li><li>A sturdy carrier or crate for each cat or dog. In addition to easing transport, these may serve as your pet's most familiar or safe space in an unfamiliar environment;</li><li>A favorite toy and/or blanket;</li><li>If your pet is prone to anxiety or stress, the American Kennel Club suggests adding <a href="https://www.akc.org/expert-advice/home-living/create-emergency-evacuation-plan-dog/" target="_blank" rel="noopener noreferrer">stress-relieving items</a> like an anxiety vest or calming sprays.</li></ul><p>In the not-unlikely event that you and your pet have to shelter in different places, your kit should also include:</p><ul><li>Detailed information including contact information for you, your vet, and other emergency contacts;</li><li>A list with phone numbers and addresses of potential destinations, including pet-friendly hotels and emergency boarding facilities near your planned evacuation routes, plus friends or relatives in other areas who might be willing to host you or your pet;</li><li>Medical information including vaccine records and a current rabies vaccination tag;</li><li>Feeding notes including portions and sizes in case you need to leave your pet in someone else's care;</li><li>A photo of you and your pet for identification purposes.</li></ul>
5. Be Ready to Evacuate at Any Time<p>It's always wise to be prepared, but stay especially vigilant in high-risk periods during fire or hurricane season. Practice evacuating at different times of day. Make sure your grab-and-go kit is up to date and in a convenient location, and keep leashes and carriers by the exit door. You might even stow a thick pillowcase under your bed for middle-of-the-night, dash-out emergencies when you don't have time to coax an anxious pet into a carrier. If forecasters warn of potential wildfire, a hurricane, or other dangerous conditions, bring outdoor pets inside so you can keep a close eye on them.</p><p>As with any emergency, the key is to be prepared. As the American Kennel Club points out, "If you panic, it will agitate your dog. Therefore, <a href="https://www.akc.org/expert-advice/home-living/create-emergency-evacuation-plan-dog/" target="_blank" rel="noopener noreferrer">pet disaster preparedness</a> will not only reduce your anxiety but will help reduce your pet's anxiety too."</p>
Evacuating Horses and Other Farm Animals<p>The same basic principles apply for evacuating horses and most other livestock. Provide each with some form of identification. Ensure that adequate food, water, and medicine are available. And develop a clear plan on where to go and how to get there.</p><p>Sheltering and transporting farm animals requires careful coordination, from identifying potential shelter space at fairgrounds, racetracks, or pastures, to ensuring enough space is available in vehicles and trailers – not to mention handlers and drivers on hand to support the effort.</p><p>For most farm animals, the Red Cross advises that you consider precautionary evacuation when a threat seems imminent but evacuation orders haven't yet been announced. The American Veterinary Medical Association has <a href="https://www.avma.org/resources/pet-owners/emergencycare/large-animals-and-livestock-disasters" target="_blank">more information</a>.</p>
Bottom Line: If You Need to Evacuate, So Do Your Pets<p>As the Humane Society warns, pets left behind in a disaster can easily be injured, lost, or killed. Plan ahead to make sure you can safely evacuate your entire household – furry members included.</p>
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