Health & Fitness

Intermittent Fasting: A Guide to Benefits and Best Practices

Recent studies hint that intermittent fasting might help you lose weight. It could also be good for your brain and heart.1 Intermittent fasting (IF) isn’t a diet where you pick certain foods. Instead, you choose when to eat. This makes it more of a lifestyle choice than a strict diet. Many people fast for their faith, like in Islam, Christianity, Judaism, and Buddhism.

Key Takeaways

  • Intermittent fasting has been shown to aid in weight loss and fat burning.
  • It may improve insulin sensitivity, reduce inflammation, and benefit brain health.
  • Fasting can increase human growth hormone (HGH) levels and promote cellular repair.
  • Intermittent fasting may not be as beneficial for females and can disrupt hormones.
  • Proper precautions and medical supervision are recommended for certain individuals.

What is Intermittent Fasting?

Intermittent fasting (IF) is not a diet. It’s a way of eating that involves fasting and then eating. It’s popular because it may help manage weight and has other health and fitness benefits. Unlike diets that tell you what to eat, IF tells you when to eat.

Fasting and Eating Periods

One common approach to IF is fasting for 16 hours and then eating in an 8-hour window.2 Some choose to fast for 24 hours a few times weekly.2 While fasting, it’s okay to drink things like water, black coffee, and tea.3

Metabolic Switching

During a fast, your body goes through changes. Levels of human growth hormone (HGH) go up. This helps with things like burning fat. Also, your body becomes better at using insulin. Insulin levels drop as well.3 This all helps with weight loss and health benefits.

When you don’t eat, your cells start repairing themselves. Genes that help you live longer and avoid diseases become more active.3 So, fasting can be really good for you.

Evolutionary Perspective

Fasting has been part of human life for a long time. We’ve evolved to go without food for periods. This natural eating habit might be better for us than eating small meals all day long.3

Intermittent Fasting MethodsDescriptionKey Benefits
16/8 MethodFasting for 16 hours and eating during an 8-hour window2Promotes weight loss and fat burning1Improves insulin sensitivity and reduces inflammation3Easier to maintain long-term
5:2 DietEating normally 5 days a week and restricting calories to 500-600 on 2 non-consecutive days1Helps with weight management and overall health3May be more sustainable than daily fasting2Can improve glucose regulation and increase ketone production
Alternate Day FastingFasting every other day, either completely or with a small calorie allowance2Can increase longevity in animal studies1May reduce insulin resistance and inflammation3Requires strong discipline and may be difficult to sustain

Popular Intermittent Fasting Methods

Intermittent fasting (IF) is not just one way of eating. It includes different cycles of not eating and then eating. There are popular methods like the 16/8 method, the 5:2 diet, and alternate day fasting.145

The 16/8 Method

The 16/8 method is called the Leangains protocol. It sets an 8-hour period for eating and a 16-hour break from food.1 You can adjust this schedule to match when you’re most active. The aim is to cut down on calories and possibly help with losing weight and keeping your body healthy.4

The 5:2 Diet

The 5:2 diet means you eat regularly for 5 days, then limit yourself to 500–600 calories on two days.145 It might be a good way to eat fewer calories through the week and keep your weight in check.

Alternate Day Fasting

With alternate day fasting, you fast every other day. Some plans cut your food down to 500 calories on fasting days.5 This method might help with losing weight and keeping your metabolism in shape. But, it might also raise your bad cholesterol if you do it for a long time.5

When picking an IF method, talking to a doctor is wise, especially if you have health issues. Ensuring you drink enough water, choose foods rich in nutrients, and stay active can make your fasting times better and boost the positives of intermittent fasting.14

How Intermittent Fasting Affects the Body

When you do intermittent fasting, your body changes in big ways at a tiny level. For starters, the hormone that helps burn fat and keep muscles, HGH, goes up.3 This also means your body gets better at using insulin, which helps control blood sugar and might lower the risk of type 2 diabetes.3

Human Growth Hormone Levels

Eating this way can really boost HGH, or human growth hormone. HGH does a lot for us, from helping us burn fat to growing muscle.3 So, fasting might help you look and feel better, just by changing when you eat.

Insulin Sensitivity

With intermittent fasting, insulin sensitivity gets a lot better. That means your body deals well with insulin, which helps keep your blood sugar in check.3 It can also cut down on inflammation and lower your risk for illnesses like type 2 diabetes.

Cellular Repair and Gene Expression

When you fast, your cells clean house. They take out the trash, getting rid of stuff that’s no good anymore.3 This can protect you from diseases and maybe slow down aging. Fasting also influences some genes in ways that are good for staying healthy.

All these internal changes from intermittent fasting are a really good thing for your health. They help with weight, keeping diseases away, and even with aging to some degree.3 Knowing how intermittent fasting works can help you decide if it’s right for you.

Weight Loss and health and fitness Benefits

Many people start intermittent fasting to lose weight. It helps you eat less without trying. This is because you have a smaller eating window.

6 IF changes how your hormones work. This helps lower insulin and raise HGH. Both changes can speed up how you burn calories.

Fat Burning and Calorie Reduction

Research shows IF can help with weight control. It lowers insulin resistance and swelling.7 Doing 15 minutes of moderate exercise every day can help burn 100 more calories.6

6 Over time, this adds up to losing a lot of weight. For example, burning 700 calories weekly equals losing 10 pounds in a year.

Insulin Resistance and Inflammation

Moving your body often can make your muscles stronger. It also helps send more oxygen to your tissues, improving your stamina.7

7 Plus, it raises HDL cholesterol and lowers bad triglycerides. This makes you less likely to get insulin resistance and inflammation.

Brain Health and Physical Performance

Exercise boosts brain chemicals that make you feel good and lower stress.7 It also enhances sleep and energy, which can make you perform better physically.7

7 But, we still need to learn more about how IF affects our health and fitness in the long run.

Who Should Be Cautious or Avoid It?

Intermittent fasting (IF) is great for some people, but not all. If you’re underweight or have had an eating disorder, talk to a doctor before starting.8

For women, the story is a bit different. Some studies suggest that IF might not be good for them. It could mess with their hormones, making their periods and health worse.8 Women should be careful, start slow, and quit if they feel it’s affecting their menstrual cycle.

If you have health issues like diabetes or low blood pressure, or are on specific meds, always check with your doc first before starting IF.8 They can give you advice that’s just for you to stay safe.

Getting Started with Intermittent Fasting

If you’re thinking about trying intermittent fasting (IF) for weight loss and better health, choose what works for you. The 16/8 method is popular because it’s simple and easy to keep up with. It means you fast for 16 hours and eat during an 8-hour window every day.1

Choosing the Right Method

Try the 16/8 method first. If it feels good and you’re handling the fasting well, you can go for harder methods like the 5:2 diet or alternate day fasting.1 The 5:2 diet lets you eat normally for 5 days but limits you to 500–600 calories the other 2 days. Alternate day fasting means you don’t eat every other day.

You could also simply skip meals from time to time whenever it suits you.1 If you’re busy or not hungry, it’s a great way to get some of IF’s benefits without a strict schedule. Try different ways and see what you like and what fits your life best.

Adjusting to the Practice

It might take your body two to four weeks to get used to intermittent fasting. During this time, you could feel weak, hungry, or notice changes in how your brain works.1 But keep at it, and most people find they can handle fasting and enjoy the health perks, like losing weight and lowering inflammation.


Intermittent fasting (IF) isn’t a must-do for everyone. It’s a lifestyle choice that might boost your health. The key things are eating nutrient-dense foods, doing regular exercise, and getting enough sufficient sleep for a healthy life.9

IF can help with weight management and keep diseases at bay. But, pick a method that suits you. Talk to a doctor if you have health issues before you start a fasting plan.9

The trick is to try different things and see what fits your life best. IF can improve your health and fitness journey. But, remember, it’s just one piece. You still need to eat a balanced, nutrient-rich diet and stay active.10


What is intermittent fasting?

Intermittent fasting (IF) switches between fasting and eating times. It focuses on when to eat, not what to eat.

How does intermittent fasting affect the body?

Fasting boosts HGH levels and lowers insulin rates. It starts cellular repair and tweaks gene function for health.

What are some popular intermittent fasting methods?

There’s the 16/8 method, fasting for 16 hours and eating in an 8-hour window. Another is the 5:2 diet, eating 500-600 calories on two nonconsecutive days. You can also fast every other day.

How can intermittent fasting benefit weight loss and overall health?

IF helps lose weight by cutting calories and changing hormone levels. It could also better health markers like insulin resistance and brain function.

Who should be cautious or avoid intermittent fasting?

It’s not for those underweight, with eating disorders, or specific health issues. Talk to a doctor if you have diabetes or blood sugar problems before starting.

How can I get started with intermittent fasting?

The 16/8 method is an easy first step. Try different ways and see what fits your life best. Remember, it takes time for your body to adapt.

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