Intermittent fasting, or IF, is a cyclic eating pattern that has been gaining massive traction over the past few years.
Despite the emergence of new dietary trends on a daily basis, intermitting fasting continues to be one of the most popular diets on the planet.
Perhaps the major factor that made this diet this popular is its non-restrictive nature, which means that people are not mandated to starve themselves or exclude a primary macronutrient from their meals.
All you need to do is consume foods during a certain period then fast for the rest of the day. While you are in the non-fasting time-windows, there are no restrictions on the type or amount of food you’re allowed to eat, which is an appealing concept for most people.(1)
At first, this concept may seem too simplistic; however, the weight loss and positive health benefits that result from intermittent fasting are unequivocal.(2)
In this article, we will comprehensively cover the major eating plans of intermittent fasting, as well as the expected benefits supported by clinical studies.
The primary eating plans of intermittent fasting
The 5:2 plan
During the 5:2 plan, your week is divided into two separate periods:
A 2-day fasting period during which your caloric intake should be under 500 calories per day.
A 5-day non-fasting period, where you’re back to a normal diet.
Note that the 2 days of fasting mustn’t be consecutive and should be separated by at least one non-fasting day.
To reduce your feelings of hunger during fasting, experts recommend including complex carbohydrates to prolong satiety.
Alternate day fasting
As the name implies, the alternate-day fasting revolves around fasting one day, then going back to your normal diet the next day.
In simpler terms, this is a 3:4 or 4:3 plan.
Note that experts do not recommend starting with this plan since it’s more advanced, which is why it’s preferred by people who have gotten used to IF.
The 16:8/14:10 plan These two plans are by far the most popular, especially among beginners.
The 16:8 entails fasting for 16 hours during the day and consuming all your calories in the 8-hour window.
Perhaps the reason behind the popularity of this dietary plan goes back to the fact that we already fast for 8 hours every day when we sleep.
This means that you only need to fast for an additional 8 hours before having your first meal. Many people take this one step further to ease the process by starting their fasting 4 hours before sleeping. This way, all they have to do is wait 4 hours when they wake up before having the first meal.
The most commonly asked question about this type of diet is the amount and type of food that you can consume during the 8-hour window of non-fasting.
The answer to this question is simple:
Intermitting fasting’s primary principle is to not impose dietary or caloric restrictions, which means you can consume all the food you want when you’re not fasting.
With that being said, moderation is crucial to make this process successful.
As for the 14:10 plan, it is basically a replica of the 16:8 plan, with one major difference; the non-fasting period is extended by 2 hours.
Note that the 14:10 plan is highly encouraged in individuals who have never tried intermittent fasting before.
The whole-day fasting plan
This plan falls on the extreme side of intermitting fasting, as it mandates having 0 caloric intake during a 24-hour fasting window.
Consequently, you may experience signs and symptoms of sugar deprivation, such as nausea, lethargy (tiredness), dizziness, myalgia (muscle pain), headaches, extreme feelings of hunger, and confusion.
Despite these adverse effects, the whole-day fasting plan is extremely popular, which is mainly due to the resulted weight loss.
The major health benefits of intermittent fasting
Intermittent fasting can drastically improve your health by targeting several body functions, including:
This is the main reason people start intermitting fasting as it could lead to rapid weight loss.
When researchers studied this phenomenon to get a full grasp of the underlying mechanisms, they found that intermittent fasting-related weight loss is due to caloric deficit, efficient hormonal regulation, and decreased insulin resistance.(3)
Moreover, the basal metabolic rate (BMR) in people on the intermittent fasting diet significantly increased.(4)
If you’re not familiar with BMR, it is a parameter used by nutritionists and fitness experts to estimate how many calories your body needs per day to keep the organs functioning.
This parameter is subject to numerous factors, including age, gender, weight, height, body type, diet, degree of physical activity, and genetics.(5)
Unfortunately, most diets slow down BMR, which decreases the rate of weight loss. Fortunately, intermitting fasting seems to be the exception to this rule. (6)
Decreased insulin resistance
Insulin resistance is a major cause of weight gain and obesity.
Fortunately, several studies concluded that intermitting fasting improves insulin sensitivity and helps in the regulation of blood sugar levels. (7)
These findings suggest that intermitting fasting is quite beneficial for pre-diabetic individuals and people looking to improve their fitness.
Improved cardiovascular health
Intermittent fasting increases the efficiency of cardiac function and reduces the risk of diseases, such as coronary artery disease (CAD).(8)
This will allow you to be more efficient during exercises to reach optimal performance and increase the degree of weight loss.
Reduction in oxidative stress
Our cells are packed with compounds known as reactive oxygen species (i.e., free radicals), which disintegrate the structure of foreign pathogens (e.g., bacteria, viruses, parasites).(9)
These compounds are critical for the function of the immune system since they ensure the sterility of the organism; however, they have one fatal flaw! Reactive oxygen species are non-specific, which means they target foreign pathogens and your tissues the same way.(10)
To keep this system in check, the body has a reserve of antioxidants that neutralize the action of free radicals after completing thedestructive journey.
Unfortunately, an imbalance in this system often occurs, where the number of free radicals exceeds that of antioxidants, leading to a metabolic state referred to as oxidative stress. (11)
The latter precipitates a myriad of pathologies, including cardiovascular disease, diabetes, infections, and neurodegenerative ailments (e.g., Alzheimer’s disease, Parkinson’s disease).(12)
In one study, researchers analyzed the effects of intermittent fasting on oxidative stress and found that it leads to a significant reduction in free radicals, which tempers down inflammation and tissue destruction, explaining why intermittent fasting protects against coronary artery disease.(13)
Decreased risk of some cancers
Cancer is a debilitating disease that’s responsible for taking millions of lives every year. The primary pathological feature of cancer is the uncontrolled growth of rogue cells, which leads to the compression and destruction of adjacent tissues.(14)
Interestingly, IF showed impressive results in slowing down the growth of tumors and preventing them altogether. (15)
Note that the conducted studies tested laboratory animals (e.g., rats), which means that we cannot generalize these findings for humans. However, the preliminary results are quite promising.
Intermitting fasting is a fantastic diet that offers a myriad of health benefits, including –and not exclusive to– the ones listed above.
As researchers conduct more experiments, they keep uncovering new positive health effects of this diet. With that being said, beginners should approach it with caution to avoid any unnecessary adverse effects.
1-Rynders, C. A., Thomas, E. A., Zaman, A., Pan, Z., Catenacci, V. A., &Melanson, E. L. (2019). Effectiveness of intermittent fasting and time-restricted feeding compared to continuous energy restriction for weight loss. Nutrients, 11(10), 2442.
2-Mattson, M. P., & Wan, R. (2005). Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. The Journal of nutritional biochemistry, 16(3), 129-137.
3-Anson, R. M., Guo, Z., de Cabo, R., Iyun, T., Rios, M., Hagepanos, A., ... & Mattson, M. P. (2003). Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. Proceedings of the National Academy of Sciences, 100(10), 6216-6220.
4-de Azevedo, F. R., Ikeoka, D., &Caramelli, B. (2013). Effects of intermittent fasting on metabolism in men. Revista da AssociaçãoMédicaBrasileira (English Edition), 59(2), 167-173.
5-Hulbert, A. J., & Else, P. L. (2004). Basal metabolic rate: history, composition, regulation, and usefulness. Physiological and Biochemical Zoology, 77(6), 869-876.
6-Mansell, P. I., & Macdonald, I. A. (1990). The effect of starvation on insulin-induced glucose disposal and thermogenesis in humans. Metabolism: clinical and experimental, 39(5), 502–510. https://doi.org/10.1016/0026-0495(90)90009-2
7-Barnosky, A. R., Hoddy, K. K., Unterman, T. G., &Varady, K. A. (2014). Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Translational Research, 164(4), 302-311.
8-Kroeger, C. M., Klempel, M. C., Bhutani, S., Trepanowski, J. F., Tangney, C. C., &Varady, K. A. (2012). Improvement in coronary heart disease risk factors during an intermittent fasting/calorie restriction regimen: Relationship to adipokine modulations. Nutrition & metabolism, 9(1), 98.
9-Murphy, M. P. (2009). How mitochondria produce reactive oxygen species. Biochemical journal, 417(1), 1-13.
10-Yu, B. P. (1994). Cellular defenses against damage from reactive oxygen species. Physiological reviews, 74(1), 139-162.
11-Sies, H. (2000). What is oxidative stress?. In Oxidative stress and vascular disease (pp. 1-8). Springer, Boston, MA.
12-Liguori, I., Russo, G., Curcio, F., Bulli, G., Aran, L., Della-Morte, D., ... &Abete, P. (2018). Oxidative stress, aging, and diseases. Clinical interventions in aging, 13, 757.13-
13-Johnson, J. B., Summer, W., Cutler, R. G., Martin, B., Hyun, D. H., Dixit, V. D., Pearson, M., Nassar, M., Telljohann, R., Maudsley, S., Carlson, O., John, S., Laub, D. R., & Mattson, M. P. (2007). Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free radical biology & medicine, 42(5), 665–674. https://doi.org/10.1016/j.freeradbiomed.2006.12.005
15-Siegel, I., Liu, T. L., Nepomuceno, N., &Gleicher, N. (1988). Effects of short-term dietary restriction on survival of mammary ascites tumor-bearing rats. Cancer investigation, 6(6), 677-680.