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Home » OSL Blog » What Is Intermittent Fasting (IF): All You Need to Know

What Is Intermittent Fasting (IF): All You Need to Know

August 22, 2019

Key Takeaways

  1. Intermittent fasting (IF) involves periods of food restriction followed by periods of feeding.
  2. This dietary pattern has emerged as a safe, effective way to lose fat, preserve lean mass, and improve glycemic control.
  3. In clinical trials, fasting increased growth hormone levels by a staggering 2,000%.
  4. Combining the keto diet and intermittent fasting can help you enter ketosis faster and speed up fat loss.

Intermittent fasting is touted as the ultimate strategy for fat loss and general well-being. Proponents say that it can improve cardiovascular health, melt belly fat, protect against cancer, and increase lifespan. But can you really trust these claims? 

This may come up as a surprise, but intermittent fasting is one of the few science-backed ways to get leaner, healthier, and more energized. It can improve your blood lipids and insulin levels, reduce DNA damage, and boost your brainpower. 

The best part is that it doesn’t involve complex meal plans or calorie counting. You can eat anything you want and still reap the benefits. Sure, if you eat clean, that’s even better! 

So, how does intermittent fasting work? Is it sustainable in the long-term? Most importantly, is it safe? Let’s find out! 

Intermittent Fasting 101: What You Should Know about the Latest Health Trend

Fasting has been practiced for centuries as a way to connect with the inner self as well as for religious purposes. Today, it’s considered an effective strategy for weight loss and better health. A growing number of elite athletes and dieters resort to intermittent fasting to get fitter, slim down, and ward off diseases. 

Intermittent fasting
Intermittent fasting alternates between periods of feeding & food restriction.

Intermittent fasting (IF), though, isn’t the same as traditional fasting. The latter is more of a spiritual practice and involves abstaining from food for days or weeks at a time. Intermittent fasting, on the other hand, alternates between periods of feeding and food restriction. 

Several versions exist and each requires a different approach. Most IF protocols involve fasting for at least 8 hours. In fact, you might already be using this strategy without realizing it. 

Let’s say you have your last meal of the day at 8 PM and your first meal at 10 AM the next day. That’s a 14-hour fast. 

cellular repair
Intermittent fasting supports cellular repair and renewal.

When you abstain from food for several hours, your hormone levels shift and your body undergoes a number of changes. Here’s a quick breakdown of the processes triggered by intermittent fasting: 

  • Cellular repair — Intermittent fasting induces autophagy, leading to better protection against infection and diseases. Basically, it rids your body of unnecessary or dysfunctional cellular material and promotes cellular renewal. 
  • Insulin levels decrease — This dietary plan helps reduce insulin and blood sugar levels, which in turn, leads to improved glycemic control. In the long run, it may lower your risk of diabetes, insulin resistance, and metabolic syndrome. 
  • The aging process slows down — Intermittent fasting and caloric restriction, in general, increase the levels of β-hydroxybutyrate (β-HB), a ketone molecule that delays vascular aging. 
insulin levels
IF as a way of eating helps reduce insulin and blood sugar levels.

These are just a few of the things that happen in your body during fasting. You may experience greater energy and stamina, enhanced mental focus, fat loss, and much more. 

Types of Intermittent Fasting

Have you ever considered fasting for 16 or 24 hours? Would you prefer fasting twice a week rather than daily or every other day? No problem. 

A cool thing about IF is that it offers a lot of flexibility. Depending on your preferences, you can fast for 8 hours, 12 hours, 24 hours, and so on. 

There are several types of intermittent fasting, so go ahead and choose the one that fits your lifestyle. 

1. Alternate Day Fasting 

This variation is ideal for those with a busy schedule. If you have a hard time planning your meals, look no further. Eat like you usually do on feeding days and abstain from food every other day. It’s that simple. 

Alternate fasting is about abstaining from eating on specific days & eating regularly on others.

In a 14-week study, subjects who combined endurance exercise and alternate day fasting experienced a decrease in body weight, fat mass, waist circumference, and bad cholesterol while preserving lean mass. 

Another study, which appeared in the journal Free Radical Biology & Medicine, has found that alternate day fasting may help reduce inflammation and oxidative stress. Subjects also experienced a significant reduction in triglycerides and cholesterol levels. 

Furthermore, alternate day fasting combined with a high-fat diet, such as the ketogenic diet, is just as effective as alternate day fasting combined with a low-fat diet. So if you’re on the keto diet, you can resort to IF to get faster results and break keto plateaus. 

Keto Supplements

Our latest keto supplements will make everything a lot easier. They are designed to maximize fat loss, ignite your energy, and improve your body’s ability to burn fat for fuel. 

Try them yourself — it might be exactly what you need to lose those last few pounds and get shredded for a contest or photo-shoot. 

2. The 16/8 Method 

Another way to incorporate IF into your lifestyle is fasting for 16 hours each day. This approach is more flexible than alternate day fasting, allowing you to fit two, three, or more meals into your diet. 

16/8 fasting
The 16/8 fasting method is when you fast for 16 hours and end up with 8 hour eating window per day.

For example, you can take your last meal or snack at 7 PM and breakfast at 11 AM the next day. That’s a 16-hour fast. Do it on a daily basis to reap the benefits. 

Also known as Leangains, this fasting protocol is a good choice for most people. It’s sustainable in the long run and doesn’t leave you feeling hungry. 

You can also try the 14/10 method, which is quite similar to Leangains. With this approach, you must fast for 14 hours per day and split your meals over 10 hours. 

3. Eat Stop Eat 

This IF protocol involves fasting for 24 hours once or twice per week. Like other intermittent fasting methods, it doesn’t limit your food choices. 

There’s just one rule: you can’t fast on consecutive days

For example, you can eat normally from Monday to Wednesday, abstain from food on Thursday, resume your diet on Friday and Saturday, and fast again on Sunday. 

4. The Warrior Diet 

Do you get hunger pangs late at night? Have a busy schedule during the day and prefer to eat later in the evening? If so, the Warrior Diet is your best bet. 

warrior diet
The warrior diet involves fasting all day & eating a huge meal at night.

This intermittent fasting method was designed by Ori Hofmekler, a renowned fitness expert. It involves fasting all day and eating one huge meal at night. 

The best part is that you’re allowed to eat small amounts of fruits and veggies during the day. If you’re hungry, you can snack on apples, berries, watermelon, veggie sticks, and so on. This makes the Warrior Diet ideal for those who want a quick source of fuel before or after training. 

Unlike other IF variations, this method emphasizes clean eating. In fact, it’s quite similar to the paleo diet. Hofmekler recommends the consumption of whole foods while limiting starches, grains, and processed products. 

The paleo diet, or the caveman diet, actually incorporates intermittent fasting. After all, our hunter-gatherer ancestors didn’t have access to food around the clock. Check out our guide to the caveman diet to see how it works! 

What Can You Eat on Fasting Days? 

Some IF variations are more flexible than others. Most plans allow the consumption of non-caloric beverages, such as: 

sparkling water
Most fasting plans allow non-caloric beverages like sparkling water.
  • Plain water
  • Sparkling water
  • Seltzer water
  • Unsweetened coffee
  • Unsweetened tea, hot or iced
  • Water + greens powder
  • BCAAs

Feel free to eat anything you want during the feeding window. However, calories and macros still count. If you binge on junk food and ice cream, don’t expect results. Intermittent fasting isn’t a free pass to binge eating. 

Coffee is another non-caloric drink you can consume & it’ll give you an energy boost.

Fill up on protein and vegetables between fasting periods to get the most out of your diet. A high protein intake will help you preserve lean mass, reduce muscle loss, and keep your metabolism up. 

If your goal is to torch fat, swap starches for leafy greens, zucchini, cucumbers, and cruciferous vegetables. They’re high in fiber and low in calories, keeping you full longer. 

You can eat anything you want during the feeding window
You can eat anything during the feeding window but a healthy diet is always the way to go.

Snack on nuts and seeds to get omega-3s in your diet and ward off hunger. These foods are rich in polyunsaturated fats, leading to improved appetite control and greater satiety. Therefore, they can make fasting easier. 

What about building mass?

To build mass, load up on high-protein, high-carb, and nutrient-dense foods during the feeding window. Fatty fish, beef, Greek yogurt, cottage cheese, walnuts, almonds, pumpkin seeds, brown rice, quinoa, and sweet potatoes are all a great choice. Make sure you take in more calories than you burn. 

Get Shredded to the Bone

Sometimes, diet and training are not enough to lose weight. Your body has an amazing ability to adapt to exercise, low-carb diets, low-fat diets, and everything in between. That’s why pro bodybuilders start dieting months before setting foot on stage and experiment with different strategies. 

One way to avoid and bust plateaus is to incorporate fasting into your daily routine. Hundreds of studies show a direct link between intermittent fasting and weight loss. 

2019 Case Study

A 2019 case report featured in the journal Cureus indicates that IF can reduce body weight within days. The subject — a healthy but slightly overweight man — went on a two-day fast, ate normally for another five days, and then repeated the cycle three times. 

By the end of the study, he lost 2.8 pounds and experienced a dramatic reduction in blood sugar levels, total cholesterol levels, blood pressure, and inflammatory markers. His cholesterol levels fluctuated, though. These changes occurred in as little as three weeks. 

cardio HIIT
Combining fasting and HIIT maximizes the benefits of intermittent fasting.

According to a recent review, intermittent fasting can be just as effective for weight loss as long-term dieting. When combined with high-intensity interval training, its benefits are even greater. For example, a study conducted on mice suggests that combining fasting and HIIT may attenuate the damage caused by bad eating. 

Now let’s take a look at a meta-analysis published in Current Obesity Reports

As the researchers note, intermittent fasting not only facilitates weight loss, but it may also improve body composition and cardiovascular health. Furthermore, it has been proven effective against visceral fat, a type of adipose tissue linked to heart disease, insulin resistance, cancer, and premature death.

Intermittent Fasting on Keto — A Foolproof Way to Shed Stubborn Fat 

We’ve published several posts over the past months to help you get started with the keto diet. Our team described the best keto shortcuts, the benefits of dietary fat, how to break keto plateaus, and more. 

As we all know, getting shredded isn’t as easy as it seems. You can’t just cut back on carbs and calories and expect to lose fat overnight. It took you months or years to gain that extra weight — so it won’t go away within days. 

Speed Up Fast Loss

However, there are ways to speed up fat loss without resorting to extreme measures. 

keto meal
Combining keto & IF supports ketosis & increases the production of ketones.

For example, you can combine the keto diet and intermittent fasting. This approach makes it easier to achieve ketosis and increase the production of ketone bodies so you can burn more fat. 

Glycogen stores and insulin levels drop during fasting, causing your body to start using fat for fuel. Additionally, combining keto and intermittent fasting may lead to faster results than the diet alone. That’s because IF stimulates thermogenesis, leading to greater energy expenditure. 

Intermittent fasting suppresses appetite & help you control your hunger.

One of the primary advantages of intermittent fasting lies in its ability to suppress appetite. As a result, you’ll find it easier to stick to your diet and eat clean. In fact, most people say that hunger goes away after fasting for two days or so. 

Additionally, your exercise performance won’t suffer during a fast. This means that you can keep working out without feeling tired or fatigued. 

During fasting, your exercise performance won’t suffer.

Not to mention that fasting is ketogenic. As mentioned earlier, this dietary pattern raises beta-hydroxybutyrate levels. The same happens when you’re on the keto diet. 

Intermittent Fasting Boosts Anabolic Hormones 

Need more reasons to give intermittent fasting a try? This eating plan can skyrocket your growth hormone levels, according to a study published by Intermountain Healthcare

anabolic hormones
If boosts the growth hormones & facilitates building mass & strength.

The researchers have found that HGH levels increased by 2,000% in men and 1,300% in women during a 24-hour fast. Furthermore, IF may help reduce the number of fat cells, preserve lean mass, and protect against cardiac events, as reported in the above study. 

Elevated HGH levels make it easier to build mass and strength while maintaining a low body fat percentage. 

lean mass
IF elevates HGH hormone levels which increases fat burning & athletic performance.

This hormone boosts your resting metabolic rate and increases fat oxidation, enhances athletic performance, and improves muscle-to-fat ratio, according to a study featured in The Journal of Pediatrics. The research was conducted on children, but its findings apply to individuals of all ages. 

Recover Faster from Training 

The increase in growth hormone levels leads to faster post-workout recovery. HGH increases muscle protein synthesis and stimulates the anaerobic energy system, leading to improved performance and faster muscle repair. 

Increased HGH hormone also leads to faster & better recovery.

Need extra help to recover from training? Then you might want to check out Old School Labs’ Classic BCAA Powder, our signature recovery formula. 

Each serving delivers 5,000 milligrams of BCAAs plus probiotics for a stronger immune system and better digestion. Our Classic BCAA Powder is sugar-free and gluten-free, contains no GMOs, and acts quickly. 

Are There Any Risks? 

Current evidence suggests that intermittent fasting is likely safe for healthy adults. Let’s take a recent study published in the journal Obesity, for example. 

Studies show that obese subjects had a considerate reduction in weight on IF.

Obese subjects who underwent intermittent fasting for two months experienced a similar reduction in weight, body composition, and blood lipids as those on a calorie-controlled diet. 

However, the IF group lost more fat mass and preserved more lean mass — without the risk of regaining the lost weight. As the researchers point out, fasting is safe and sustainable in the long run.

Like everything else, this dietary plan has its drawbacks, though. 

At the beginning IF might leave you with a grumbling stomach & occasional overeating.

First of all, you might notice your stomach grumbling, especially in the first few days of fasting. Secondly, you might end up overeating during the feeding period. If you don’t watch your calorie intake, you may end up gaining weight. 

Dealing with Tiredness

Another drawback is the tiredness experienced by most dieters. Again, this symptom tends to occur in the first few days. It’s more common among those who are new to intermittent fasting. As your body adapts, you’ll regain your energy and start feeling better. 

Fatigue is another side effect of IF & any diet.

Try to get more rest and take time to recover from training. If possible, hit the gym on your non-fasting days or during feeding periods. Stress can drain your energy, so squeeze more “me” time into your schedule. 

Mood swings, irritability, anxiety, and fatigue are all common side effects of intermittent fasting. The good news is, these issues will go away within days. If you fast regularly, you may not experience these problems at all.

Beware, though, that this eating pattern isn’t for everyone.

 If you have higher caloric needs, such as when recovering from an illness or surgery, fasting isn’t the best choice. Also, it can do more harm than good to those struggling with eating disorders like anorexia and bulimia. 

Should You Try It?

All in all, intermittent fasting is a proven way to get leaner, fitter, and healthier. It’s not a magic bullet to fat loss or a cure-all, but it can make a huge difference in your life. Remember — there’s no one-size-fits-all approach when it comes to nutrition. 

What’s your take on intermittent fasting? Are you ready to give it a try? Let us know what you think in the comment section below!

Disclaimer: None of the individuals and/or companies mentioned necessarily endorse Old School Labs or COSIDLA Inc. products or the contents of this article. Any programs provided for illustration purposes only. Always consult with your personal trainer, nutritionist and physician before changing or starting any new exercise, nutrition, or supplementation program.
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  • This article was very insightful. My wife has done intermittent fasting and it worked like a charm. Now that i know more about it per this article i can maybe try it myself

  • I have practiced intermittent fasting for several years. I find that it just works best with my schedule and it is much more enjoyable to have a larger amount of food in a shorter period of time. It is a great tool to make a caloric deficit more feasible!

  • I tried intermittent fasting in college for four months. I lost 20 pounds and dropped my weight from 240 to 220ish. I mostly followed the 16/8 method and I would actually fast until 1 pm and have my last meal around 9 pm, mainly because I knew I would get out of football practice late and I didn’t want to go home hungry. Perhaps the warrior diet would have been a little bit better but I had no idea that it even existed until I read this article. But intermittent fasting is something I would definitely try if you’re looking to not just lose weight but, also, learn more about your diet and see how your body reacts to certain foods. I know I learned that I preferred white rice instead of brown rice while fasting on most days. Another interesting thing I would love to try next off-season would be the keto diet combined with the intermittent fasting. Great article!

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