Before You Try Intermittent Fasting
If you want to give intermittent fasting a try, make sure to discuss it with your doctor first, says Dr. Rimm. Skipping meals and severely limiting calories can be dangerous for people with certain conditions, such as diabetes. Some people who take medications for blood pressure or heart disease also may be more prone to imbalances of sodium, potassium, and other minerals during longer-than-normal periods of fasting.
Drawbacks Of 16/8 Intermittent Fasting
16/8 intermittent fasting may be associated with many health benefits, but it does come with some drawbacks and may not be right for everyone.
Restricting your intake to just eight hours per day can cause some people to eat more than usual during eating periods in an attempt to make up for hours spent fasting.
This may lead to weight gain, digestive problems and the development of unhealthy eating habits.
16/8 intermittent fasting may also cause short-term negative side effects when youre first getting started, such as hunger, weakness and fatigue though these often subside once you get into a routine.
Additionally, some research suggests that intermittent fasting may affect men and women differently, with animal studies reporting that it could interfere with fertility and reproduction in females .
However, more human studies are needed to evaluate the effects that intermittent fasting may have on reproductive health.
In any case, be sure to start gradually and consider stopping or consulting your doctor if you have any concerns or experience negative symptoms.
Restricting daily food intake may cause weakness, hunger, increased food consumption and weight gain. Animal studies show that intermittent fasting may impact men and women differently and may even interfere with fertility.
Be Mindful Of Your Snacking Urges
If youre a chronic snacker or binge eater, you may find that your habits are a response to your emotions. Food can offer solace from external stressors and mental health issues. Sometimes, we simply snack as a reflex response to boredom. Be mindful of why youre snacking, how quickly youre eating and how present you are when you eat. Addressing the root trigger behind bad habits is key to stopping them. And of course, when you do reach for a snack, opt for clean, nutritious options.
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A Lifestyle Not A Diet
Professor Mark Mattson, a Professor of Neuroscience at John Hopkins University recently authored a review paper published in the New England Journal of Medicine on intermittent fasting and its role in health, ageing and disease. He says the first thing to know about fasting is that it should not be thought of as a short-term regime. “Intermittent fasting should not be considered a diet, rather an eating pattern that is committed to long term in order to reap the potential benefits.”
Its Inappropriate For Many People
The Warrior Diet is not a way of eating that everyone should follow.
This type of intermittent fasting is inappropriate for many people, including:
Some women may be able to fast intermittently without negative effects. However, some may experience unpleasant side effects like insomnia, anxiety, missed periods and reproductive health disturbances.
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Fasting And The Keto Diet
You can also combine fasting with a ketogenic diet.;
Several of the benefits of intermittent fasting come from your body being in ketosis a state in which you burn fat as your main energy source.;
By eating a ketogenic diet, you can get your body into ketosis before you start fasting. A keto diet suppresses hunger and improves your health on its own. Pairing it with fasting provides even more health benefits.;;
You can start a keto diet today with a quick trip to the grocery store.;
Frequently Asked Questions Concerns And Complaints
Im a woman. Should I do anything differently?
I havent worked with women on implementing an intermittent fasting schedule, so I cant speak from experience on this one.
That said, I have heard that women may find a wider window of eating to be more favorable when doing daily intermittent fasting. While men will typically fast for 16 hours and then eat for 8 hours, women may find better results by eating for 10 hours and fasting for 14 hours. The best advice I can give anyone, not just women, is to experiment and see what works best for you. Your body will give you signals. Follow what your body responds favorably to.
Also, if youre a female, there is an allfemale page on Facebook that discusses intermittent fasting. Im sure you could find a ton of great answers and support there.
I could never skip breakfast. How do you do it?
I dont. Breakfast foods are my favorite, so I just eat them at 1pm each day.
Also, if you eat a big dinner the night before, I think youll be surprised by how much energy you have in the morning. Most of the worries or concerns that people have about intermittent fasting are due to the fact that they have had it pounded into them by companies that they need to eat breakfast or they need to eat every three hours and so on. The science doesnt support it and neither do my personal experiences.
I thought you were supposed to eat every 3 hours?
Here’s why this was a popular idea for a brief period of time:
Here’s the problem:
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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 cant always be explained by the loss of muscle mass alone .
Severe calorie restriction over a long period can cause your metabolic rate to drop, as your body enters so-called starvation mode. The scientific term for this is adaptive thermogenesis.
Your body does this to conserve energy as a natural defense against starvation .
This has been demonstrated dramatically in a study of people who lost large amounts of weight while participating in The Biggest Loser, a reality show on TV.
Participants followed a calorie-restricted diet and intense exercise regimen to lose large amounts of weight .
The study found that 6 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 (
Why Might Changing Timing Help
But why does simply changing the timing of our meals to allow for fasting make a difference in our body? An;in-depth review of the science of IF;recently published in;New England Journal of Medicine;sheds some light. Fasting is evolutionarily embedded within our physiology, triggering several essential cellular functions. Flipping the switch from a fed to fasting state does more than help us burn calories and lose weight. The researchers combed through dozens of animal and human studies to explain how simple fasting improves metabolism, lowering blood sugar; lessens inflammation, which improves a range of health issues from arthritic pain to asthma; and even helps clear out toxins and damaged cells, which lowers risk for cancer and enhances brain function. The article is deep, but worth a read!
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Why Intermittent Fasting Is Bad
For some people who decide to start following an intermittent fasting schedule, they dont improve their diet at the same time. They instead eat a bunch of unhealthy food during their eating window, which causes them to miss out on many of the benefits that intermittent fasting can produce. By not eating a healthy diet, they tend to overeat and binge during the eating window, which leads to not feeling well and having low energy levels.
If you are underweight then dont try and fast for long periods of time, the same goes for people who have eating disorders. Fasting can become problematic, even dangerous in such cases.
Getting enough water can be a problem for some people as they are often eating fewer meals, not feeling hunger and not really paying attention to how much water they are drinking.
Some people become irritable during the first few days of fasting. This is especially true if you are used to snacking a lot between meals and following an unhealthy diet. Make healthier food choices during your eating window to improve your mood and general well being.
Feeling excessively hungry between meals is also common for some people when they first start an intermittent fasting program. There are many ways you can avoid this, one being limiting or eliminating the amount of refined carbohydrates that you eat during your eating window, and to avoid snacking between meals.
What Are The Possible Side Effects
There can be a number of possible side effects of intermittent fasting.40 Heres what to do if you encounter them:
- Hunger is the most common side effect of intermittent fasting. This may be less of an issue if youre already on a keto or low-carb, higher-fat diet.41Learn more
- Constipation is common. Less going in means less going out. However, keep in mind this is a normal response to eating less. It is not a concern and shouldnt require treatment unless you experience significant bloating or abdominal discomfort. Standard laxatives or magnesium supplements can be used, if needed.
- Headaches are common and tend to disappear after the first few times on fasts.42 Taking some extra salt often helps mitigate such headaches.43
- Mineral water may help if your stomach tends to gurgle.
- Other possible side effects include dizziness, heartburn and muscle cramps. Learn more
A more serious side effect is the refeeding syndrome. Fortunately, this is rare and generally only happens with extended fasts when one is undernourished.44
Since most of these side effects are manageable, they do not mean you have to stop your fast. However, if you truly feel unwell, are excessively dizzy, profoundly weak or have other severe symptoms, then you should break your fast.
Just remember to go slowly when you break it and prioritize fluids and salt . And of course, if the symptoms persist, see your doctor immediately.
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So Which Intermittent Fasting Schedule Is Best For Weight Loss Whichever One You’ll Actually Stick To Tbh
In short, the one that’s easiest for you to follow. “It is all about sustainability for the individual,” says Lemein. “If one of these diets work well for you and your lifestyle and preferences, then you will likely see some success. If not, then you’ll likely not see the results you’re are looking for, as the sustainability piece will not be there.” That means picking a diet that work best with all the lifestyle factors you need to consider, like your work schedule, family dynamic, living situation, commute time, and travel commitments, notes Lemein.
It’s worth pointing out, though, that the 16:8 diet seems to be the most doable for a lot of people who are into IF. The 16:8 method also scores points for preventing overeating at night, which can often be a big obstacle for weight loss. And sticking to an eight-hour eating window during daylight hours allows your metabolism to run as itâs supposed toâyou fuel up for energy during the day , and stop eating for rest and recovery at night, per a 2017 article in the journal Nutrition Reviews.
The bottom line: All intermittent fasting schedules may lead to weight loss if you can follow them sustainably, and the 16:8 method may be the easiest way to follow an IF diet.
Examples Of Different Intermittent Fasting Schedules
If youre considering giving fasting a shot, there are a few different options for working it into your lifestyle.
Daily Intermittent Fasting
Most of the time, I follow the Leangains model of intermittent fasting, which uses a 16hour fast followed by an 8hour eating period. This model of daily intermittent fasting was popularized by Martin Berkhan of Leangains.com, which is where the name originated.
It doesn’t matter when you start your 8hour eating period. You can start at 8am and stop at 4pm. Or you start at 2pm and stop at 10pm. Do whatever works for you. I tend to find that eating around 1pm and 8pm works well because those times allow me to eat lunch and dinner with friends and family. Breakfast is typically a meal that I eat on my own, so skipping it isn’t a big deal.
Because daily intermittent fasting is done every day it becomes very easy to get into the habit of eating on this schedule. Right now, you’re probably eating around the same time every day without thinking about it. Well, with daily intermittent fasting it’s the same thing, you just learn to not eat at certain times, which is remarkably easy.
Weekly Intermittent Fasting
One of the best ways to get started with intermittent fasting is to do it once per week or once per month. The occasional fast has been shown to lead to many of the benefits of fasting we’ve already talked about, so even if you don’t use it to cut down on calories consistently there are still many other health benefits of fasting.
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What Is 1: 6 Intermittent Fasting
18:6 involves fasting for 18 hours out of the day, leaving you with a six-hour eating window. This could mean eating lunch at 12:30 p.m., a snack at 3 p.m., then finishing dinner by 6:30 p.m. This is a much more rigid form of intermittent fasting and definitely best saved for experienced fasters who’ve tried other methods. This plan might be right for you if your weight loss has stalled doing 16:8 or if you tend to overeat with a longer eating window.
What Defines Successful Fasting
Is fasting just skipping meals? Not exactly.
As Zane explains, Theres more than one way to fast. Generally speaking, our dependence on body fat for fuel starts to be elevated after about 12 hours of not taking in any sort of calories.
At its core, intermittent fasting is putting at least a 12-hour window between meals.
After 12 hours, your body is mobilizing excess fat to burn energy.; This means that an extended period without caloric intake jumpstarts weight loss and creates a healthy gap that gives your body a chance to regain homeostasis.
So what exactly defines successful fasting? Put simply, a successful fast means staying out of your bodys way for 12 hours or more. Rather than overloading with food every few hours, successful fasting gives your body the opportunity to reset, recalibrate, and burn fat.
The most effective intermittent fasting uses a 14 to 18-hour window of no-calorie intake followed by a 10 to 6-hour window of healthy eating.
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Jumping Right In And Powering Through Whatever Happens
As with all big life changes, its unwise to dive in headfirst rather than gently wading in. If you go straight to a 16:8 intermittent fast when your body is used to eating constantly, you might have side effects from such a rapid change. Its better to gradually work up to a 16:8 intermittent fast.
If you typically eat breakfast at 8am, you can push it to 9am the first morning, 10am the following morning, and so on until you are ready to skip breakfast altogether. If youre used to having a midnight snack, make it earlier and earlier until you no longer take it. Its important to give your body a chance to adjust to this new reality.
There are some side effects that you need to be wary of. If you experience extreme headaches, dizziness, anxiety, irritability, chills, or fatigue, you may need to break your fast. Dont just stubbornly push through. Your body is trying to tell you something.
Intermittent fasting isnt for everyone. If you have these symptoms on a regular basis, you may need to look into an alternative way to meet your health goals. Theres nothing wrong with making a safe choice for your body.
How Much Weight Loss Can You Expect In A Month On Intermittent Fasting
Many factors go into how much weight you actually lose on intermittent fasting. Weight loss will depend on your current weight, metabolism, what you eat, and your activity levels. Obviously, if you follow a healthy eating pattern and exercise every day or a few times a week, it will help you shed weight faster.;
Intermittent fasting may enable you to lose between 0.51.5 pounds a week. In 4 weeks, you could lose anything between 26 pounds.;
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Should You Do Intermittent Fasting And The Keto Diet
We have a crazy extensive guide on the Keto Diet;in case youre not familiar with it, so here it is in a nutshell:
This process is called ketosis, and there are two ways for a body to enter ketosis:
- Eating in a way that induces ketosis .
- FastingHey, thats what youre reading about right now!
We actually have an amazing success story here on Nerd Fitness, Larry, who followed our strategies, went Keto and start intermittent fasting. He ended up losing weight, getting stronger, AND overcame the challenges of rheumatoid arthritis !
Heres how the fasting portion of it works:
As your body enters a fast period when there are no sources of glucose energy readily available, the liver begins the process of breaking down fat into ketones.
Fasting itself can trigger ketosis.
Fasting for a period of time before kicking off a Keto-friendly eating plan COULD speed your transition into the metabolic state of ketosis, and fasting intermittently while in ketosis could help you maintain that state.
I personally love fasting for the simplicity: I skip breakfast every day and train in a fasted state. Its one less decision I have to make, its one less opportunity to make a bad food choice, and it helps me reach my goals.
WHY KETO + IF WORKS = eating Keto can be really challenging. And every time you eat, its an opportunity to do it wrong and accidentally eat foods that knock you out of ketosis.
Youre also tempted to overeat.
Your value may vary!
You need to decide what works for you.