Intermittent Fasting May Be As Effective For Weight Loss As Cutting 500 Calories A Day Research Suggests
Diet plans that limit when you eat, and not much else, can lead to weight loss and improve metabolic health, according to a new review.
Intermittent fasting a diet that reportedly helped stars including Jennifer Aniston, Kourtney Kardashian, and Chris Pratt shed unwanted pounds, according to People has been transcending its status as a celebrity fad as research about its weight loss and other benefits continues to emerge. The latest, a review published in October 2021 in Annual Review of Nutrition found that intermittent fasting leads to roughly the same amount of weight loss as traditional calorie-restrictive diets, and may improve other markers of cardiometabolic health as well.
One of our main findings was that people who do intermittent fasting lose about the same amount of weight as people on a regular calorie-restriction diet that cuts out 500 calories a day, says lead author Krista Varady, PhD, researcher and professor of nutrition at the University of Illinois, Chicago.
Additionally, Dr. Varady notes that intermittent fasting appears to help with metabolic health. It did help lower blood pressure, she says. Some studies reported decreases in LDL cholesterol and triglycerides, and insulin resistance.
How To Begin 16 8 Fasting
For people that get hungry first thing in the morning, this 16 8 Fasting schedule may be a bit tough to embrace. My suggestion is to push back the morning window by 30 minutes every day or two until youre comfortable waiting until 12pm to begin your 8 hour eating window.
You can also consider drinking water, coffee and other drinks that have no calories. This does help reduce the feelings of hunger and make it a little easier to transition.
What Is Intermittent Fasting And Why Would You Do It
Intermittent fasting is not a diet, it’s a pattern of eating. It’s a way of scheduling your meals so that you get the most out of them. Intermittent fasting doesnt change what you eat, it changes when you eat.
Why is it worthwhile to change when youre eating?
Well, most notably, its a great way to get lean without going on a crazy diet or cutting your calories down to nothing. In fact, most of the time you’ll try to keep your calories the same when you start intermittent fasting. Additionally, intermittent fasting is a good way to keep muscle mass on while getting lean.
With all that said, the main reason people try intermittent fasting is to lose fat. We’ll talk about how intermittent fasting leads to fat loss in a moment.
Perhaps most importantly, intermittent fasting is one of the simplest strategies we have for taking bad weight off while keeping good weight on because it requires very little behavior change. This is a very good thing because it means intermittent fasting falls into the category of simple enough that you’ll actually do it, but meaningful enough that it will actually make a difference.
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How To Do It
The easiest way to follow the 16:8 diet is to choose a 16-hour fasting window that includes the time that a person spends sleeping.
Some experts advise finishing food consumption in the early evening, as metabolism slows down after this time. However, this is not feasible for everyone.
Some people may not be able to consume their evening meal until 7 p.m. or later. Even so, it is best to avoid food for 23 hours before bed.
People may choose one of the following 8-hour eating windows:
- 9 a.m. to 5 p.m.
- 10 a.m. to 6 p.m.
- noon to 8 p.m.
Within this timeframe, people can eat their meals and snacks at convenient times. Eating regularly is important to prevent blood sugar peaks and dips and to avoid excessive hunger.
Some people may need to experiment to find the best eating window and mealtimes for their lifestyle.
You Are Eating The Wrong Type Of Food
Many other diets come with a list of foods that you can and cannot eat. However, that is not how intermittent fasting works.
Intermittent fasting lets you eat anything you would like within a specific eating window.
Because intermittent fasting does not restrict your diet, it is easy to slip right into unhealthy feeding habits. Binging on unhealthy processed foods even if it is only in your eating window could be responsible for your slow results.
Stuffing too many calories during your eating periods is also counterproductive.
During your intermittent fast, consider changing your meal plan. Toss out the unhealthy processed food and switch to healthier options. Think of foods like whole grains that are rich in dietary fiber.
Staying away from sugary foods protects you from sugar highs and the sugar crash that results after. It also helps keep your blood sugar within the normal range.
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Does It Work For Weight Loss
Several studies show that intermittent fasting may boost weight loss via several mechanisms.
First, restricting your meals and snacks to a strict time window may naturally decrease your calorie intake, which can aid weight loss.
Intermittent fasting may also increase levels of norepinephrine, a hormone and neurotransmitter that can boost your metabolism to increase calorie burning throughout the day .
Furthermore, this eating pattern may reduce levels of insulin, a hormone involved in blood sugar management. Decreased levels can bump up fat burning to promote weight loss .
Some research even shows that intermittent fasting can help your body retain muscle mass more effectively than calorie restriction, which may increase its appeal .
According to one review, intermittent fasting may reduce body weight by up to 8% and decrease body fat by up to 16% over 312 weeks .
Does Intermittent Fasting Work
Intermittent fasting is one of the hottest new diet trends. Proponents say it can help you lose weight, improve blood sugar metabolism, and slow aging
One of the biggest diet and nutrition trends these days is intermittent fasting. Every week, I hear from listeners wanting to know my thoughts on it. I’ve mentioned intermittent fasting on the podcast before, in an episode on the health benefits of fasting. But that was way back in 2011. At that point, the research was still quite preliminary and most of it had been done in rodents. Nonetheless, researchers were excited about the potential for intermittent fasting to prevent or reverse diabetes, weight gain, DNA damage, and other artifacts of aging.
Based on these promising but preliminary results, lots of people started experimenting with various forms of modified or intermittent fastinggenerating a lot of positive anecdotal reports. Over the last few years, more studies have been donesome of them on actual humans.
Getting Started With If
If you use the IF method, you should still pay attention to what you eat. It is still important to get vitamins, proteins, minerals, fiber and hydration. IF creates a calorie deficit because you are limiting eating opportunities. Although that allows you to eat two larger meals that may be less healthy and tastier, while keeping a calorie deficit, your body still responds to what you put into it. So cleaner, healthier food is better than junk food.
If your main goal is health benefits and not loss of body fat or weight, counting calories is probably not necessary. As you move closer to your goal, make sure you are getting your macronutrients.
Theres an adjustment period when you start using an IF method and you may become lightheaded as your body adjusts to longer periods without food. If you feel an overwhelming need for food, or become nauseous or dizzy, eat or drink something.
Exercising is perfectly fine while fasting. If your main goal is to lose body fat, try working out at the end of your fast and right before your feeding window. Youll burn calories when your body is already primed to be using fat as a main source of fuel, and you sensitize your muscles to the protein and nutrients youre about to feed it. If youre an explosive athlete, however, try working out in the middle of the feeding window so youll have available carbohydrates in your system that are vital for performance.
The Best Intermittent Fasting Methods For Women
So, what exactly is a relaxed approach to intermittent fasting? Again, since theres little research done on intermittent fasting, were dealing with a bit of a gray area. The opinions also tend to vary depending on which site you visit, or which health expert you ask. From what weve found, the general guidelines to brief intermittent fasting for women are:
Do not fast for longer than 24 hours at a time Ideally fast for 12 to 16 hours Do not fast on consecutive days during your first two to three weeks of fasting Drink plenty of fluids during your fast Only do light exercise on fasting days, such as yoga, walking, jogging, and gentle stretching
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The Science Behind Intermittent Fasting
One of the major keys to understanding fasting, to understanding really any diet, is understanding the role insulin plays, Dr. Hutchins says. Insulin, the hormone that regulates blood sugar, is made in the pancreas and released in the bloodstream in response to eating. Once released, insulin causes the body to store energy as fat. Insulin makes fat, so the more insulin made, the more fat you store, he says.
During intermittent fasting, the periods when you are not eating give the body time to lower insulin levels, which reverses the fat-storing process. When insulin levels drop, the process goes in reverse and you lose fat.
Two other hormones, ghrelin and leptin, are also at work. Ghrelin is the hunger hormone and tells you when youre hungry. Some data suggest that intermittent fasting can decrease ghrelin, Dr. Hutchins says. Theres also some data that says theres an increase in leptin, which is the satiety hormone. Thats the one that says, Hey, Im full.
With more leptin and less ghrelin, people will feel fuller faster and hungry less often, which could translate to fewer calories consumed and, as a result, weight loss.
Dont Compare Yourself To What Others Are Doing
Kayla G., a 33-year-old registered dietitian, has been doing intermittent fasting for more than a year and says shes a huge fan of the eating plan. Intermittent fasting has allowed me to lose that stubborn last five pounds and, more importantly, maintain it, she says.
She usually stops her fast between 12 and 1 p.m. and finishes her last meal between 6 and 8 p.m. My best advice would be, Dont compare yourself to what others are doing, she says. Find a regimen that works best for you.
Everyone has a different metabolism and goals, Kayla points out, adding, Don’t be afraid to use trial and error to see what works best for you and your body.
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Weight Loss Requires A Caloric Deficit Intermittent Fasting Does This Automatically
The reason any weight loss diet works is because it reduces your total calorie intake .
This means youll burn more calories than you consume , leading to weight loss.
Intermittent fasting is no exception to this rule.
Skipping entire meals greatly reduces your calorie intake So much so that you dont really have to worry about calories in the meals you do eat.
Given the average woman might aim for 1600-1800 calories per day to lose weight, thats a whopping 30% of calories saved instantly.
If you skip the morning food, even indulging in two large 750 calorie meals later that day, plus a 300 calorie dessert would keep most on track for weight loss.
Summary: Weight loss requires you to consume fewer calories than you burn. Missing one meal per day by fasting can save around 30% of calories in one go.
Should You Try Intermittent Fasting For Weight Loss
There are many effective ways to lose weight, and intermittent fasting is one but its one of many.
Some people find missing just one meal extremely challenging, so its definitely not for everyone.
Also know that some women report issues with menstruation and even fertility problems from long-term fasting. I recommend joining if you want to join the discussion.
And as always you should consult with your doctor before trying any new diet, especially if you take medication.
However, if you are someone who:
- wants to lose belly fat
- is able to skip meals or at least breakfast without complaint
- wants to spend less on food
- wouldnt mind going to the toilet fewer times in a week
- wants to do a lot less cooking and cleaning
intermittent fasting could be game-changing for you.
About Joe Leech, Dietitian
Joe Leech is a university-qualified dietitian from Australia.
He graduated with a Bachelor’s degree in exercise science, followed by a Master’s degree in Nutrition and Dietetics in 2011.
Learn more about him on the About page.
Joe Leech, Dietitian
The Backstory On Intermittent Fasting
IF as a weight loss approach has been around in various forms for ages but was highly popularized in 2012 by BBC broadcast journalist Dr. Michael Mosleys TV documentary Eat Fast, Live Longer and book The Fast Diet, followed by journalist Kate Harrisons book The 5:2 Diet based on her own experience, and subsequently by Dr. Jason Fungs 2016 bestseller The Obesity Code. IF generated a steady positive buzz as anecdotes of its effectiveness proliferated.
In the Obesity Code, Fung successfully combines plenty of research, his clinical experience, and sensible nutrition advice, and also addresses the socioeconomic forces conspiring to make us fat. He is very clear that we should eat more fruits and veggies, fiber, healthy protein, and fats, and avoid sugar, refined grains, processed foods, and for Gods sake, stop snacking.
Intermittent Fasting Can Help Weight Loss
IF makes intuitive sense. The food we eat is broken down by enzymes in our gut and eventually ends up as molecules in our bloodstream. Carbohydrates, particularly sugars and refined grains , are quickly broken down into sugar, which our cells use for energy. If our cells dont use it all, we store it in our fat cells as, well, fat. But sugar can only enter our cells with insulin, a hormone made in the pancreas. Insulin brings sugar into the fat cells and keeps it there.
Between meals, as long as we dont snack, our insulin levels will go down and our fat cells can then release their stored sugar, to be used as energy. We lose weight if we let our insulin levels go down. The entire idea of IF is to allow the insulin levels to go down far enough and for long enough that we burn off our fat.
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What Types Of Intermittent Fasting Plans Lead To Weight Loss
The review included studies on three types of intermittent fasting:
- Alternate day fasting , which typically involves a day of unrestricted eating alternated with a fasting day where 500 calories consumed in one meal account for the total daily calorie intake
- The 5:2 diet, a modified version of alternate day fasting that involves five feasting days and two fasting days per week.
- Time-restricted eating , which limits eating to a specified number of hours per day , followed by 16 hours of fasting
Its worth noting that the review wasnt designed to compare the effectiveness of different types of intermittent fasting plans because the studies were done in different groups of people and using different parameters. But the results did indicate that individuals who followed either the alternate-day diet or the 5:2 plan both averaged a loss of around 7 percent of their body weight , and were able to maintain that loss for a year. Despite fasting much less frequently than alternate-day fasters, subjects who participated in the 5:2 diet lost an equivalent amount of weight, a finding that surprised researchers.
While all plans led to some weight loss, following a time-restricted eating plan was the least effective plan for shedding pounds. In total, participants with obesity who followed a time-restricted eating plan lost an average of 3 percent of their body weight.
Why Is If Better Than A Regular Diet
Depending on the diet, intermittent fasting may reduce the amount of muscle loss and avoid the decrease in metabolism thats often seen with longer-term calorie restriction . Nothing in particular says it is better, compared to any other. Its just another tool to try, and one that happens to be very effective.
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What To Do Ifintermittent Fasting Stops Working
In the modern world, its very easy to get what you want immediatelywithout having to work for it. You can just order 10 000 calories to yourdoorstep without leaving the couch, eat it within a few hours, and get all theentertainment you desire. However, some things like your health and fitness requiremore effort and theyre worth working for.
Instead of wanting immediate gratification, realize that consistency and delayed return will make you a better person. Not only will you be more likely to achieve your goals but youll also develop more willpower, self-discipline, and character. This kind of mindset will carry over to other areas of your life as well and youll be more successful in everything else you do.
If you want to start intermittent fasting with resistance training, then check out my Metabolic Autophagy Master Class. Its a 13-hour video course with dozens of videos and a 4-week meal plan/workout routine that tells you exactly what to do and how.