Benefits Of Intermittent Fasting – The Truth About This Diet

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By Thomas Youngerman

Reviewed by Juliana Tamayo, MS, RDN - Last Updated

Benefits Of Intermittent Fasting

The typical Western diet, heavy on red meat, refined sugars, processed foods, and saturated fats, can lead to weight gain, a higher risk of obesity, type 2 diabetes, and a host of other serious illnesses. Those extra calories and a sedentary lifestyle may cause you to age prematurely as well. Now scientific studies show that intermittent fasting can help you manage your weight and prevent or reverse these trends.

There is no scientific basis for the traditional three square meals a day, plus snacking prevalent in the Western diet. Perhaps for our hunter-gatherer ancestors, fasting was more the norm. What is apparent is that our diet should include more fresh fruits and vegetables, clean protein, healthy fats and fiber, and less refined sugar and grains, processed foods, and less snacking—maybe even fewer meals, taken less frequently, such as with intermittent fasting.

So, what exactly is intermittent fasting? That’s a great question! In this guide, we will define intermittent fasting and its various forms. We will explain what happens to your body while fasting and, of course, talk about all the major benefits of intermittent fasting. Let’s get started so you can decide if fasting is right for you. 

Intermittent Fasting

What Is Intermittent Fasting?

Although touted for its ability to help you manage weight, intermittent fasting is not a diet – it is an eating pattern that focuses on when you eat, not what you eat. When practicing IF, you alternate between fasting and eating on a regular schedule. Many people combine intermittent fasting with a Ketogenic, Paleo, slow-carb, or reduced carb diet. One of the benefits of IF is that it mimics metabolic responses similar to a calorie restriction (CR) diet – important as CR has been shown to have significant benefits in laboratory studies relative to lifespan and disease avoidance. 

What Is Intermittent Fasting

Fasting and calorie restriction diets have received a good deal of press lately due to their potential for life extension and delaying the onset of age-related disorders. To clarify, they are not the same. CR is a consistent pattern of reducing your average daily caloric intake, while fasting relates to the frequency of eating or time-restricted eating where you do not eat during certain times of the day, week, or month. 

Which leads us to the more popular types of fasting. 

Types Of Intermittent Fasting

There are numerous different types of fasting and intermittent fasting. There are “purge” fasts, “detox” fasts, and other types of periodic fasting that can last for multiple days. However, for our purposes, we will focus on intermittent fasts, which are of shorter duration and practiced with greater regularity. The primary variable in IF is the amount of time between meals.

The 12-Hour Method

Another popular method as most of the fasting is done while sleeping. An example would be to have your last meal at 7 p.m. and your next meal at 7 a.m. Studies indicate that intermittent fasts must last at least twelve hours to be beneficial.

12-Hour Method Of Intermittent Fasting

The 16/8 Method

The 16/8 method is one of the two most common methods and one of the easiest to sustain. On the 16/8, you fast after your evening meal, skipping breakfast entirely and not eating for sixteen hours. Your evening meal is then consumed within the next eight hours. Rinse and repeat.

The Fast 5 Method

Fast for nineteen hours beginning at bedtime, followed by five hours of eating as much as necessary to satisfy hunger. This is a popular method among the weight-loss crowd.

The Fast 5 Intermittent Fasting Method

One Meal A Day Method

As the name indicates, you have one meal per day – within a one-hour window. You fast for twenty-three hours of the day.

Alternate Day Method

You fast for twenty-four hours and eat to satisfy the hunger for the next twenty-four hours.

The 5:2 Method 

You normally eat for five days of the week. For the other two days, you restrict caloric intake to about one-third of your usual calories, 500 calories for women – 600 for men. 

Although the 5:2 method features time restrictions, it is not truly fast and is closer to a CR diet strategy.

What Happens To Your Body When Fasting

With the typical Western diet, people eat throughout the day, often snacking in addition to meals. As a result, their body burns sugar (glucose) as its primary fuel for energy. Following the Western diet over time, you become more insulin-resistant, leading to weight gain, obesity, type 2 diabetes, and other diseases. 

The objective of intermittent fasting (and CR) is to flip the metabolic switch from glucose to fatty acid-derived ketones as your primary fuel. When you limit your eating window beyond twelve hours, you give your body time to digest, repair cells, and produce beneficial hormones to make stored body fat more accessible.

Benefits Of Intermittent Fasting


Many of the benefits of intermittent fasting are related to these changes in hormones and cell function. Insulin levels drop, which facilitates fat burning. Human growth hormone (hGH) levels increase dramatically, beneficial for muscle gain and fat burning. Senescent cells (older, dying cells) are removed, and autophagy (cellular detox) increases.

Benefits Of Intermittent Fasting

Although not a diet, weight loss is one of the many benefits of intermittent fasting. When fasting beyond twelve hours, the body’s liver glycogen stores are depleted, fatty acids are mobilized, and fatty acid-derived ketones are produced. Your body begins to use energy reserves stored in fat for fuel. These lower insulin levels, higher growth hormone levels, and ketones all increase body fat breakdown and facilitate its use for energy. 

Intermittent Fasting Diet

The anti-aging and life extension potential of CR and intermittent fasting are well documented and supported by long term laboratory studies. Other benefits of intermittent fasting include:

    • Reduces insulin resistance and your risk of type 2 diabetes
    • Improves cardiovascular health
    • Reduces free radical damage and chronic inflammation 
    • Initiates “autophagy” – cleaning out damaged cells
    • May help prevent Alzheimer’s Disease
    • Help brain cells work at full capacity
    • May reduce the risk of cancer – proven effective in animal laboratory studies
  • May protect patients against the harmful side effects of chemotherapy or radiation therapy 

Clinical Studies Of IF And CR

When scientists study longevity, two factors seem to be involved in virtually every study:

  1. Of our most long-lived people, none are overweight
  2. Practicing a vegan, vegetarian, or reduced-calorie diet has health benefits in disease avoidance and weight control. Remember, intermittent fasting mimics the effects of CR. 

In lab experiments, calorie-restricted feeding has delayed the onset of age-related disorders and, in some studies, extended the lifespan of a variety of animals, including worms, crabs, snails, fruit flies, and rodents. Prompted by this success, the U.S. Department of Health and Human Services’ National Institute on Aging (NIA) conducted two studies with rhesus monkeys to determine if the benefits of calorie restriction are evidenced in longer-lived species. 

In both studies, the monkeys were kept on a calorie-restriction diet (30 percent fewer calories than for monkeys in the control groups) for more than 20 years. Although there were differences between the two studies—including monkey breed and type of food—both provided evidence that calorie restriction reduced the incidence of age-related conditions, such as cancer, heart disease, and diabetes. One study found an extension of lifespan, while the other did not. Many of the monkeys are still alive, so the full impact of calorie restriction on their maximum lifespan has yet to be determined.

Other studies have focused on what happens to the body when caloric intake is restricted and confirm that certain processes such as metabolism, inflammation, cellular activities, and oxidative stress have beneficial results. These processes all play a role in regulating the rate of aging. 

The NIA has also studied the effects of intermittent fasting relating to glycogen depletion and ketone production. These chemicals (ketones) help cells, especially brain cells, operate at peak capacity. Scientific theories regarding ketones:

  • May protect against age-related decline in the central nervous system that might cause dementia and other disorders
  • May inhibit the development of cancer – malignant cells cannot obtain energy from ketones
  • May protect against inflammatory issues such as arthritis
  • Could protect against type 2 diabetes

Is Intermittent Fasting Safe?

The most obvious issue related to fasting is hunger. There are two additional hormones at work when fasting, ghrelin and leptin. Ghrelin, often referred to as the “hunger hormone,” tends to increase food intake as its levels are highest before meals and when you expect to be fed. Leptin, a hormone produced in the small intestine, helps to regulate energy balance by inhibiting hunger. Since you are not eating at normal intervals, ghrelin is the enemy. If you become hungry while fasting, have some water, tea, or black coffee. If the hunger is intolerable, eat. Other side effects of IF include:

  • Brain Fog
  • Headaches
  • Fatigue
  • Dizziness
  • Dehydration
  • Irritability

These are the same issues you might experience when entering ketosis and encounter the Keto-Flu – the body is adapting to using ketones for energy versus its normal glucose fuel. 

Some people overeat when they finally break their fast, although research indicates most people usually eat less. Combining IF with keto, paleo, or a low carb diet are excellent strategies to offset this overeating tendency – which tends to fade with experience. 

The most severe potential issue with intermittent fasting is that some people, particularly women, may create or exacerbate hormonal imbalance issues. As with any new diet regimen or supplement, we highly recommend you check with your doctor before initiating a fast. 

Supplementation And Intermittent Fasting

Another potential side effect of intermittent fasting is the potential to create nutrient deficiencies. It’s essential that you support your body with the right nutrients, so supplements may be required. Below are several nutritional supplements you may want to add to your regimen when fasting:


Your inexpensive insurance policy to meet any nutrient gaps. Some options worth checking into include PatchMD Multivitamin Patch, Ritual Vitamins, and Smarter Multivitamin.


Electrolytes are crucial when fasting. Make sure you’re getting enough sodium, potassium, magnesium, and chloride. A solid choice worth considering is Dr. Berg’s Trace Minerals.

Omega 3 Fatty Acids

Omega 3 Fatty Acids are needed within your body to function properly. They can also provide benefits such as helping to stop joint pain, lowering triglyceride levels, and providing calories to help your energy levels. If you’re looking to get more omega 3 fatty acids in your diet, some options are Performance Lab Omega-3 and Omax3.

Vitamin D3

Vitamin D3 is a common vitamin deficiency. A supplement can help benefit these levels.

B Complex

B Complex is used for energy and to enhance the absorption of minerals.

Should You Try Intermittent Fasting?

If you’ve read this far, you’ve learned of the many documented and potential health benefits of the intermittent fasting eating pattern. Although fasting may be unpleasant at first, the types of IF listed in this article are generally safe for healthy adults. People who should avoid IF are pregnant or nursing mothers, children, diabetics, and those with a hormonal imbalance or other chronic illness. Anyone considering fasting should consult with your medical professional.

The first rule when starting an intermittent fasting regimen, particularly if it’s combined with a vegan, vegetarian, keto, Paleo, or other low carb diet, is to ensure your program provides a safe level of nutrition. If you’re unsure what a safe level is for your situation, consult with your doctor or a nutritionist. 

Additional lifestyle protocols for weight loss and general wellbeing:

  • When breaking your fast – eat a healthy diet with nutritious foods, in moderate amounts
  • Move – engage in regular exercise
  • Alcohol in moderation
  • No tobacco products
  • Ample sleep – for rest & recovery 

Intermittent Fasting - IF

In Summary: Intermittent Fasting And Your Health

Weight management, obesity avoidance, reduced risk of type 2 diabetes, improved cardiovascular health, less oxidative stress, and chronic inflammation may reduce cancer. If those are not sufficient motivation to try intermittent fasting, your brain cells are not operating at peak capacity (another benefit of IF). 

We’re not suggesting a purge or detox fast lasting several days. Dip your toe in the water – start with the 12 Hour Method, and gradually expand your fasting period to the 18/6 or Fast 5 Method. Whichever method you choose, sustain the pattern for at least three weeks to start seeing results. What have you got to lose?

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Thomas Youngerman

Thomas Youngerman is an entrepreneur and author in the health and wellness space with extensive experience in the supplement industry. He has owned multiple sports nutrition stores and served as the Category Manager and Director of Business Development for a regional chain of nutrition stores. Thomas created a successful line of men’s healthy aging supplements that was distributed in GNC, The Vitamin Shoppe, and Kroger, and later sold to a West Coast corporation. Thomas was previously a certified nutrition coach. He has a strong understanding of nutrition, supplement formulations, DSHEA, cGMP, and FDA regulations.