When you think of fasting, you may think of feeling deprived of food and nutrients. However, the latest trend in fasting, known as intermittent fasting (IF), is anything but. Sure, you may have your body go through long periods of not eating then you’re used to. However, within your eating hours, experts encourage healthy eating of nutrient-dense foods.
This method of IF is not a one-size-fits-all type of diet. You can modify the times you fast and eat to fit your schedule, as you will read below. However, no matter how you do it, this method of eating has shown extensive health benefits.
Intermittent fasting is most well-known for its weight loss benefits. However, it can also help lower the risk of chronic diseases like diabetes, as you will read below. Some studies have found that it may be no more effective than other diet regimens for weight loss. But unlike other diet regimens, IF may be easier to follow for some. And if a diet regimen is easier to follow, than you’re more likely to adopt it for the long-term. In turn, your body will have more time to reap long-term health benefits.
So, let’s learn a bit more about intermittent fasting and how you can apply it to your daily routine. We’ll discuss the types of IF and the basic guidelines of this eating regimen. Finally, we’ll discuss the health benefits of IF and review the recent research that backs up these benefits. From there, you can decide if intermittent fasting is the right fit for you and your healthy lifestyle.
Basics of Intermittent Fasting
Intermittent fasting, or IF, is not your average diet regimen. It’s not necessarily a regimen that tells you what you should eat. But instead, IF is a regimen that says you when you should and shouldn’t eat. In other words, it’s a timed approach to eating.
All types of IF involve a fasting period and an eating period of the day. The fasting period is meant to provide the body time to heal and reboot itself. This reboot, in turn, can aid in lessening digestive symptoms and inflammation. Research shows that IF can help aid weight loss, improve glucose metabolism, and increases insulin sensitivity.
Types of Intermittent Fasting
IF is not just a one-size-fits-all type of regimen. There are many different forms of IF that can work for just about anyone that would like to try out this diet regimen. The most common types of IF include:
Eat Stop Eat
This method of IF is for those experienced with fasting. This is because it involves eating nothing for 24 hours twice a week on non-consecutive days. It does not matter what days a person fasts, but just that they are not on two days in a row.
This method of IF was initially created for weightlifters. It involves fasting for 14 to 16 hours and only eating for 8 to 10 hours a day. Men typically follow the longer fast, while women usually are recommended to observe the shorter fast in this range. Although no food is allowed in the fasting stages of this IF method, a person may have as many no-calorie beverages as they want. Such drinks include unsweetened tea, coffee, carbonated water, lemon water, or plain water.
This method of IF involves eating healthy, balanced meals for most days of the week. However, on two, non-consecutive days, a person will consume 500 to 600 calories a day.
Alternate Day Fasting
This method of IF is like the 5:2 method except that the low-calorie days are every other day of the week for a total of three days a week.
No matter what method of IF you follow, it’s essential that during the eating periods that you consume nutrient-dense foods. Since IF limits eating time, and since some forms of IF limit calories, it’s crucial to make every calorie count.
This means eating plenty of nutrient-dense fruits, vegetables, whole grains, lean proteins, and plant-based proteins like nuts and seeds. This will ensure that your body does not end up becoming deficient in any nutrients it needs for optimal health.
Foods You Can Eat on The IF Routine
As mentioned before, diet quality is essential during the eating periods. Researchers suggest that you should focus on the following types of foods during the eating window on IF.
Antioxidant-rich Foods Such As a Variety of Colorful Fruits and Vegetables:
It’s important to eat a rainbow of colors of produce to reap the benefits of the different antioxidants they contain. For example, orange-yellow colored produce typically contains the antioxidant group carotenoids. Carotenoids like vitamin A have beneficial effects on vision health, heart health, and cognitive function, to name a few. Produce rich in carotenoids include squash, carrots, grapefruit, oranges, and apricots, for example.
Unsaturated Fatty Acid-Containing Foods:
Healthy fats, such as those from foods high in unsaturated fats can provide antioxidant properties, which can reduce inflammation in the body. Examples of such foods high in unsaturated fats include avocados, olives, nuts, seeds, fatty fish like salmon and mackerel, as well as plant-based oils like olive oil.
Other Heart-Healthy Foods:
Research also shows that it’s important to add heart-healthy foods outside of fruits and vegetables to the IF eating period. An example of one food is curcumin, which is a component in the golden spice turmeric. You can consume this spice as a tea or used as a flavoring in various meat and vegetable dishes. Curcumin holds anti-inflammatory benefits, which research shows can lessen the risk of heart disease, diabetes, as well as other inflammatory conditions like arthritis.
Other Heart-Healthy Foods Are Those Rich in Zinc:
Zinc has an anti-atherosclerotic effect. In simpler terms, this means that zinc can help lower the risk of the hardening of the arteries that can lead to heart disease. Examples of foods rich in zinc include oysters, crab, pork, beef, beans, chicken, dried pumpkin seeds, nuts, yogurt, as well as cereals fortified with zinc.
How IF Can Improve Health
IF is a diet regimen that is well-known for its weight loss benefits. Research shows that this diet regimen can decrease fat mass and total body weight as well as help lower blood fats and “bad” LDL cholesterol levels. Not to mention that IF can help teach people how to avoid unhealthy habits like nighttime grazing and snacking that can lead to consuming excessive calories.
However, weight loss is not the only health benefit of IF. Other research shows that metabolic health improvements can occur as a result of following an IF regimen. This means that IF could potentially lower the risk of diabetes and insulin resistance. These improvements in metabolic health may stem from putting a person’s circadian rhythm back on track, positively altering the gut microbiome, as well as improving overall lifestyle behaviors.
Circadian Rhythm and IF
The circadian rhythm is the internal clock within humans that is also known as the sleep/wake cycle. The part of the brain known as the hypothalamus controls this rhythm. When the eyes sense darkness, the brain receives a signal to release the hormone melatonin that makes you tired. On the other hand, a sense of light will cause alertness.
However, the circadian rhythm can also impact other aspects of health. Experts suggest that an imbalance of the circadian rhythm can affect digestion, hormone release, and eating habits, to name a few. Causes of this imbalance include often traveling to different time zones and shift work, for example. In turn, this can lead to the body not being able to eat meals at “regular” times.
As a result, the body may release insulin, which is a hormone released when we eat, at nighttime. Over time, this may cause a disruption in the circadian rhythm that can make it hard for the body to detect day and night. This can negatively impact sleep patterns as well as hormonal release. Not to mention that a disrupted circadian rhythm can increase the risk of conditions like cardiovascular disease and type 2 diabetes.
Gut Microbiome and IF
Recent research reveals that when the gut microbiome is imbalanced, then oxidative stress-related inflammation can ensue. And when this happens, it can negatively impact many aspects of health. Besides weakening immune health, it can also increase your risk of inflammatory health conditions. Such conditions include heart disease, diabetes, skin conditions like eczema, as well as joint issues like arthritis.
Probiotics, also known as good bacteria, along with prebiotic foods that feed such bacteria can help balance the gut microbiome. In turn, they can help improve immunity and lower the risk of inflammatory health conditions. Prebiotic foods include tomatoes, artichokes, bananas, asparagus, berries, garlic, onions, chicory, green vegetables, legumes, as well as oats, linseed, barley, and wheat.
Besides adding such foods into the diet, intermittent fasting can also help improve gut health. A 2018 fruit fly study looked at the impact of IF on lifespan. Study results show that 40-days post-IF showed a significant reduction in age-related pathologies as well as the preservation of gut health.
Furthermore, a mouse study looked at the impact of IF on diabetes health. Study results show that IF restructures gut microbiota in such a way that it prevents diabetic retinopathy.
What is The Latest Research On IF?
A study published in July 2019 reports that IF may provide benefits for active individuals. This study reveals that when combined with an evidence-based exercise program IF can help with fat loss and lean mass gain. Not only that, but research shows that IF can reduce resting heart rate and blood pressure as well as increase resistance of the brain and heart to stress.
Also, animal models show that IF may help brain health. Early animal models show that IF can delay the onset and progression of neurological conditions like Alzheimer’s, Parkinson’s, and Huntington’s diseases. Also, a protocol of IF and/or vigorous exercise can improve sensory-motor function, cognition, and physical performance. It’s thought that IF helps enhance cognitive function and overall brain health by protecting the brain against inflammation.
Although many of these studies on the health benefits of IF are in animal models, there are some small human studies showing promise. One study placed a group of obese men with prediabetes on a form of IF known as early time-restricted feeding. The men were either provided meals during the eight hours between 7 am and 3 pm, or over the twelve hours from 7 am to 7 pm.
Study results show that the eight-hour group had significantly lower insulin levels, improved insulin sensitivity, decreased appetite, and lower blood pressure compared to baseline than the other group. However, more human studies that are larger are needed before definitive conclusions can be made about the IF regimen.
What to Know When Starting IF
Experts suggest that if you want to try IF, then you should be cautious when starting. This is because if you haven’t fasted before then, you may experience uncomfortable symptoms in the first week or two such as headaches, lightheadedness, or grouchiness.
Therefore, you should start with one day of moderate fasting, or consuming a very low-calorie regimen, per week. Or, you can fast for 12 hours a day and then have a 12-hour eating period. Then once your body becomes used to fasting, you can increase it to two days of fasting each week or a more extended fasting period several days a week.
Take home message on Intermittent Fasting
When you first heard of intermittent fasting, you may feel hesitant. The term fasting may bring visions of giving up favorite foods and feeling hungry all the time. However, this new trend in healthy eating encourages nutrient-dense foods and filling portions of foods.
Not to mention, IF allows your body time each day to digest and heal. This can have a positive impact on gut health. IF can help reduce inflammation, and in turn can lower the risk of chronic disease.
Now, IF won’t be the right fit for everyone because no diet is, but if you find it easier to comply with IF, then you can reap an array of health benefits that can improve your life.
Staci Gulbin, MS, MEd, RD, LDN is a registered dietitian, freelance writer, health editor, and founder of LighttrackNutrition.com. She has been a dietitian since 2010, and has helped thousands of patients in arenas like weight management, fitness, long-term care, rehab, and bariatric nutrition. Staci has also been writing and editing since 2011 for such websites as CDiabetes, Anirva, and Casa de Sante, to name a few and has been a featured expert for websites like Shape.com, ThisisInsider.com, and Eat This Not That. Staci hopes to provide others accessible, accurate, and practical health and wellness information so they can make lasting healthy lifestyle changes.