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What Are The Effects Of Fasting

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Low Fat Low Carb Or Mediterranean: Which Diet Is Right For You

The Effects of Fasting on Diabetes and Heart Disease

Losing weight sometimes takes experimentation. If you give a diet your best shot and it doesn’t work long term, maybe it wasn’t the right one for you, your metabolism, or your situation. Genes, family, your environment even your friends influence how, why, what, and how much you eat, so don’t get too discouraged or beat yourself up because a diet that “worked for everybody” didn’t pay off for you. Try another, keeping in mind that almost any diet will help you shed pounds at least for a short time.

Here’s a look at three common diet approaches.

1. Low fat: Doesn’t taste great … and is less filling

Once the main strategy for losing weight, low-fat diets are now less popular. Since fat contains nine calories per gram while carbohydrates contain four, you could theoretically eat more without taking in more calories by cutting back on fatty foods and eating more that are full of carbohydrates, especially water-rich fruits and vegetables. But if the carbs you eat in place of fat are highly processed and rapidly digested, you may be sabotaging your weight-loss plan.

2. Low carbohydrate: Quick weight loss but long-term results vary

3. Mediterranean style: Healthy fats and carbs with a big side of fruits and vegetables

Make your own

Different Types Of Fasting

Intermittent Fasting

This type of fasting is also known as cyclic fasting. Intermittent fasting is a catch-all phrase for eating intermittently. In fact, almost all of the fasting methods below are types of intermittent fasting! Typical intermittent fast times range from 14 to 18 hours. The longest period any one of these plans would require you to abstain from solid food would be about 3236 hours.

Time-Restricted Eating

If you practice time-restricted eating, youll abstain from food for anywhere between 1216 hours. During your eating window, you can eat as much of your favorite healthy foods as youd like. This is one of the most common methods of fasting.

Time-restricted eating is pretty simple to implement. If you finish dinner at 7 p.m., for instance, you wouldnt eat anything again until at least 7 a.m. If you wanted to take it further, youd extend the no-eating time until about 11 a.m. or 12 p.m. Because youre sleeping for a large chunk of the no eating time, this is a good way to introduce fasting into your lifestyle and experiment without any major changes.

16/8 Fasting

Basically another name for time-restricted eating, here youll fast for 16 hours a day and then eat the other eight.

Alternate Day Fasting

5:2 Diet

Its very similar to alternate day fasting except here, you eat normally for five days of the week. On the other two, calories are restricted to about 500600 calories a day.

The Daniel Fast

What Is Intermittent Fasting

Many diets focus on what to eat, but intermittent fasting is all about when you eat.

With intermittent fasting, you only eat during a specific time. Fasting for a certain number of hours each day or eating just one meal a couple days a week, can help your body burn fat. And scientific evidence points to some health benefits, as well.

Johns Hopkins neuroscientist , has studied intermittent fasting for 25 years. He says that our bodies have evolved to be able to go without food for many hours, or even several days or longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive and thrive for long periods without eating. They had to: It took a lot of time and energy to hunt game and gather nuts and berries.

Even 50 years ago, it was easier to maintain a healthy weight. Johns Hopkins dietitian Christie Williams, M.S., R.D.N., explains: There were no computers, and TV shows turned off at 11 p.m. people stopped eating because they went to bed. Portions were much smaller. More people worked and played outside and, in general, got more exercise.

Nowadays, TV, the internet and other entertainment are available 24/7. We stay awake for longer hours to catch our favorite shows, play games and chat online. Were sitting and snacking all day and most of the night.

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Does Intermittent Fasting Enhance Weight Loss

I didnt mention weight loss as one of the benefits of intermittent fasting and heres why its the total number of calories you consume in a day that determines weight loss, not when you eat.

Intermittent fasting can help reduce the total number of calories you consume in a day. Most intermittent fasting methods give you a small feeding window to eat all your daily calories. And its hard to overeat if you only have a few hours to eat. Subjects in a study were able to reduce their calorie intake by up to 8% when practicing intermittent fasting.

Intermittent fasting helps with weight loss only if you restrict your calorie intake too.

Note that intermittent fasting can help you lose weight only if you maintain a calorie deficit. Besides that, it has no weight loss benefits. So eating one or two meals a day wont help you lose weight if you overeat.

A group of researchers from Netherlands conducted a study to find out if intermittent fasting has weight loss benefits. They divided their subjects into two groups. One group was on a regular diet and another on an IF diet they all ate the same number of calories and had the same diet composition. And the researchers found no difference in body fat and lean body mass of the two groups after the study was complete.

Posts By Monique Tello Md Mph

The irreversible side effects of the latest dieting fad ...

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Also Check: Is Fasting Good For Losing Belly Fat

Being Uncomfortably Full After Eating

Most of us are used to eating several meals a day. This makes it easy to consume enough food without being overly full. But with a small feeding window, you have to eat one or two big meals. These big meals can leave you feeling uncomfortable and constipated. Furthermore, eating big meals at night can reduce the quality of sleep.

Most times youll be very hungry when the fasting period ends. So youll eat a lot of food and also eat again after a few hours before you start fasting again. With IF, you have to learn to handle big meals and you should be comfortable with your stomach being stretched out for a few hours. Also note that digesting a big meal can put stress on the body.

Reduction In Athletic Performance

Its okay to train moderately when fasting. But doing intense workouts like power-lifting, cross-fit, or high intensity interval training can hurt you. Research shows that athletic performance usually diminishes when fasting. In a study, Senegalese researchers tested the athletic performance of runners during Ramadhan and during non-fasting time.1

And they found that the athletic performance of the athletes reduced significantly during the month of Ramadhan. Other studies also show increase of fatigue after intense workouts when fasting.

Recommended Reading: What Is The Purpose Of Fasting During Ramadan

It Can Help You Lose Weight

Fasting every other day has been found to be just as effective for weight loss as traditional low calorie diets. Aside from the fact that youll likely end up taking in fewer calories, going longer without eating seems to have a positive effect on blood sugar and fat burning.

And youll see results pretty quickly: A 2015 review concluded that whole-day fasts could help you shed up to 6 percent of your body fat in as little as 12 weeks.

However, the way you break your fast also matters. Returning to your pre-fasting ways can result in weight regain.

May Aid In Cancer Prevention And Increase The Effectiveness Of Chemotherapy

Side Effects of Fasting

Animal and test-tube studies indicate that fasting may benefit the treatment and prevention of cancer.

In fact, one rat study found that alternate-day fasting helped block tumor formation .

Similarly, a test-tube study showed that exposing cancer cells to several cycles of fasting was as effective as chemotherapy in delaying tumor growth and increased the effectiveness of chemotherapy drugs on cancer formation .

Unfortunately, most research is limited to the effects of fasting on cancer formation in animals and cells.

Despite these promising findings, additional studies are needed to look at how fasting may influence cancer development and treatment in humans.

Summary Some animal and test-tube studies suggest that fasting could block tumor development and increase the effectiveness of chemotherapy.

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Hunger And Food Cravings

Hunger and cravings are usually a challenge for anyone trying to lose weight. If you cant control hunger and curb your cravings, you wont lose weight. Some people experience hunger pangs even when they eat six meals a day. So fasting makes their hunger much more intense. But realize its natural to feel hungry at the start of an IF diet and your body may get used to hunger with time.

May Help Prevent Cancer

Cancer is 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.

Promising evidence from animal studies indicates that intermittent fasting or diets that mimic fasting may help prevent cancer. Research in humans has led to similar findings, although more studies are needed 00224-7″ rel=”nofollow”> 26, 27, 28 ).

Theres also some evidence showing that fasting reduced various side effects of chemotherapy in humans 00503-2″ rel=”nofollow”> 29, 30).


Intermittent fasting has been shown to help prevent cancer in animal studies and some human studies. Research in humans showed that it can help reduce side effects caused by chemotherapy.

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Benefits: Start Something New

With careful planning and thought, fasting can be an incredible springboard into a healthier lifestyle. One suggestion is to make plans before you even start your fast. Write down what you’re hoping to get out of it and what you want to accomplish. If done correctly, the end of a fast is the perfect time to begin a dramatically healthier diet and lifestyle.

It Could Help Protect Against Depression

Fasting Side Effects: New Study Reveals

Fasting may have an antidepressant effect, thanks to its ability to make feel-good neurotransmitters like serotonin and endogenous opioids more available to your brain. Fasting and calorie restriction have been shown to relieve negative emotions like tension and anger and boost feelings of euphoria.

A 2008 review found that people with depression who reduced their daily calorie intake by 25 percent experienced fewer depressive symptoms over 6 months, without any apparent negative side effects.

Full disclosure: Experts still have a lot to learn about the relationship between fasting and cancer. But animal studies suggest that periodic fasting might have an anticancer effect, meaning that the practice could play a role in cancer prevention.

The research also seems to suggest that fasting could make cancer treatments like chemotherapy more effective.

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Vegetarians And Vegans May Have An Increased Risk Of Stroke

Researchers in the United Kingdom analyzed the risk of stroke and other health problems over two decades among nearly 50,000 people based on the diets they followed. The types of stroke were also analyzed, including bleeding into the brain and nonbleeding stroke . Compared with meat eaters:

  • rates of heart disease were 13% lower in pescatarians
  • rates of heart disease were 22% lower in vegetarians
  • rates of stroke were 20% higher among vegetarians. However, the overall risk was small, equal to three extra cases per 1,000 people over 10 years.
  • the higher stroke risk among vegetarians was mostly due to hemorrhagic stroke
  • the higher stroke risk was not observed among pescatarians.

If confirmed, these findings will complicate the way we look at plant-based diets. Are there serious and underappreciated downsides to these diets that should make us think twice about choosing them? Or is the increased risk of stroke heavily outweighed by cardiac and other health benefits?

This study is also a reminder that the health impact of a particular intervention may not be easy to predict or explain. In most cases, the risk of stroke and heart disease tend to rise or fall together, but that wasnt the case in this research.

Fasting And Weight Loss

If you weed through all the controversy, you’ll find that most medical experts agree on one thing: fasting is not a healthy weight loss tool.

“The appeal is that is quick, but it is quick fluid loss, not substantial weight loss,” says Madelyn Fernstrom, PhD, CNS, founder and director of the University of Pittsburgh Medical Center’s Weight Loss Management Center.

“If it’s easy off, it will come back quickly” — as soon as you start eating normally again, she says.

Even some proponents of fasting for other medical purposes do not support fasting for weight loss. Some say it can actually make weight problems worse.

“Fasting is not a weight loss tool. Fasting slows your metabolic rate down so your diet from before the fast is even more fattening after you fast,” says Joel Fuhrman MD, author of Eat to Live: The Revolutionary Plan for Fast and Sustained Weight Loss and Fasting and Eating for Health.

Fasting for weight loss carries other health risks as well.

While fasting for a day or two is rarely a problem if you are healthy, “it can be quite dangerous if you are not already eating a healthy diet, or if you’ve got liver or kidney problems, any kind of compromised immune system functioning, or are on medication — even Tylenol,” says Fuhrman, a family physician in Flemington, N.J..


In addition, other practices that are often combined with fasting for weight loss, such as colon cleansing, carry their own risks.

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Changes In Your Menstrual Cycle

Heres another side effect of sudden weight loss : Women who lose a dramatic amount of weight or are consistently not getting enough calories every day might find their menstrual cycles slow down or even stop completely.

Per the Mayo Clinic, women who have excessively low body weight are prone to a condition called amenorrhea, or the absence of menstruation. Sudden weight loss or being underweight can disrupt your typical hormone cycle and cause missed periods so while you might be rejoicing in the way IF has helped you shed pounds, you could also be depriving your body of calories it needs to function.

If you stop getting your period and think it’s linked to intermittent fasting habits you’re practicing, stop fasting and speak with your gynecologist to troubleshoot.

Metabolic Effects Of Intermittent Fasting

How Intermittent Fasting Affects Your Body and Brain | The Human Body

Annual Review of Nutrition

Vol. 37:371-393 First published as a Review in Advance on July 17, 2017

Ruth E. Patterson1,2 and Dorothy D. Sears1,2,3

1Moores Cancer Center, University of California, San Diego, La Jolla, California 92093 email:

2Department of Family Medicine and Public Health, University of California, San Diego, La Jolla, California 92093

3Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093

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Feelings Of Frustration Or Failure

“For most people it is not natural to go five or more daytime hours without eating, presenting a large challenge for those undertaking IF. Hearing from some IFers that fasting brings them clarity and focus abilities’ and has resulted in great weight loss can be defeating then for those struggling with the practice,” says Wilson. “Any healthy change will be just that: a change, but it should be a change that can exist within the framework of your current lifestyle. Feeling frustrated by the demanding structure of IF could lead to eating between meals followed by feelings of guilt and disappointment.”

Improves Your Immune System

Ever noticed that when animals fall sick, they stop eating? Have you ever wondered why this happens?

Thats a natural instinct through which the animals try to reduce the stress on their internal systems and focus their energy on battling the infection.

Therefore, next time you fall sick, resist the temptation to look for food and focus on fasting instead.

Fasting does a number of things to your immune system.

Remember, we mentioned that fasting triggers the regeneration of old cells within the body.

This includes cells that are part of your immune system.

This rejuvenation of the cells leads to improved immune function.

According to one study, a three day fast can lead to the regeneration of the entire immune system and the production of totally brand new white blood cells which have a stronger ability to fight disease.

As we saw earlier, fasting also triggers the burning of fats and the release of toxins from the body, which can also enhance the bodys ability to fight diseases.

Breaking the fast with fruits can boost your immune system even further by providing your body with a source of essential vitamins and minerals, especially Vitamins A and E which are great antioxidants.

Fasting also prevents the formation of cancer cells, regulates the likelihood of inflammation and helps reduce the occurrence of free radicals in the body, which cause damage to the cells, DNA and the bodys proteins, thus contributing to disease.

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