Your Cliff Notes Guide To Fasting
IF, 16:8, OMAD, Snake Diet, 5:2, Warrior Diet, ADF, Warrior Diet & Extended Fasts.
Your fasting questions, answered.
In the last few years, the idea of fasting and specifically, abstaining from food, has taken new hold in the health and fitness community. In 2016, Yoshinori Ohsumi won the Nobel Prize in Physiology or Medicine for the discovery of autophagy: “a fundamental process for degrading and recycling cellular components.”
What Ohsumi’s research found was that the human body begins an accelerated process of breaking down and recycling old, worn out cells to be replaced with new ones when in a fasted state. This was a groundbreaking discovery and has been used to improve health outcomes across a variety of treatments for illnesses, including cancer.
In subsequent years, this renewed interest in fasting has produced a variety of methods aimed at improving healing, weight loss, longevity, heart health, brain health, and more. While there’s a long list to the benefits of fasting, there’s a list nearly as long detailing how one should fast, including: Intermittent Fasting (IF), the 16:8 Method, One Meal a Day (OMAD), Alternate Day Fasting, the 5:2 Method, The Warrior Diet, The Snake Diet, and Extended Fasts. The following will cover the difference between these fasting methods and their resulting benefits.
INTERMITTENT FASTING (IF)
Intermittent fasting or IF is a blanket term that can include many of the other types of fasting on our list. It is simply defined as an eating pattern where you cycle between periods of eating and fasting. It doesn’t tell you which types of foods you can eat during your eating window, how long your fasts need to be, or how often they need to occur.
By this definition, everyone practices IF when they sleep each night, or even when they go a few hours between meals during the day. However, most people use the term “Intermittent Fasting” to describe a period of not eating that goes beyond a regular night’s sleep and has the goal of achieving prolonged fasting benefits.
Benefits often include: weight loss, improved metabolic health, protection against disease, and longevity.
Risks: Vary depending on the length of fast. Discussed more below.
One of the most popular ways to intermittent fast is with the 16:8 method. The 16:8 method describes fasting for 16 hours out of the day, followed by an eight hour eating window. A common way to achieve this is by skipping breakfast, or pushing your first meal of the day back by a few hours, though there is no restriction as to when your eating window needs to be. This may look like eating your first meal around noon, finishing eating your last meal before 8pm, and fasting until noon again the next day.
There are no restrictions as to the types of foods that can be eaten during your eating window or the number of meals that can be consumed, but many beneficiaries of the 16:8 method find themselves eating two, larger, healthful meals per day with limited snacking in between. This cycle can be repeated daily or a few times a week to reap the benefits.
Benefits often include: Boost in brain function and productivity, increased insulin sensitivity, enhanced longevity and weight loss.
Risks: May encourage participants to eat more than usual during their eating window, negating weight loss benefits. May interfere with fertility in women if nutritional needs are not met during the eating window.
ONE MEAL A DAY (OMAD)
One take on IF is to regularly consume just one meal a day, or follow an OMAD protocol. OMAD limits your eating window to just one meal within one hour of the day, meaning you’re fasting for the other 23 hours. OMAD has further rules to say your one meal should be regularly consumed within the same four hour time frame each day and then spaced out by the full 23 hours (no eating one meal at 11pm one night and then another at 2am the next morning!) The meal should also be of standard size, able to fit on a regular dinner plate, and piled no more than three inches high, but no constraints are put on what kind of food is eaten. During the other 23 hours, OMADers are allowed to drink water or black coffee.
While this may sound like an extremely restrictive approach, it can be helpful for some to simplify a fasting routine and free up more time in the day that’s not spent on eating or preparing meals.
Benefits often include: Increased productivity, energy, sleep, weight loss, and cardiac health; lowered blood sugar levels.
Risks: Hormonal fluctuations (especially in women), hunger, fatigue, and shakiness if assumed too quickly or if nutritional needs are not being met through the one meal a day.
Similar to OMAD, the Snake Diet includes one, large meal followed by a prolonged fasting period. In this case, that fasting period is at least 24 hours, or, “as long as possible” according to the diet’s founder Cole Robinson.
Beginning a snake diet protocol starts with a 48 hour fast where you consume only water and “snake juice”: a bare-bones type electrolyte drink made of water, sea salt, and potassium chloride. After the initial 48 hours, participants break their fast with a large, low-carb, high-fat meal and then go right back to fasting for at least the next 24 hours. Robinson also recommends taking on a 72 hour fast, consuming only “snake juice” and an apple cider/lemon juice drink, early on in your snake diet journey for supercharged fat burning and weight loss results. A full description of Robinson’s protocol can be found on his website: https://www.snakediet.com
Continuing the snake diet regularly looks similar to OMAD, but with the potential for longer fasting increments in between eating and a focus on low-carb, high-fat foods. On Robinson’s website, YouTube channel, and various Snake Diet Facebook groups, there’s also the recommendation of occasional “dry” fasts which restrict all liquids and aim to lower inflammation and blood pressure.
Benefits often include: Weight loss, improved skin, increased Human Growth Hormone (for muscle development) and increased cellular turnover (autophagy).
Risks: The Snake Diet is not currently backed by evidence beyond related research in fasting. Many participants may find the diet ultra restrictive and therefore unsustainable. Disordered eating habits may result by prolonged diet adherence. The recommendation of dry fasting could lead to electrolyte imbalances and the potentially life-threatening effects of dehydration.
The 5:2 diet describes a method of intermittent fasting that includes five days of regular calorie consumption and two days of limiting calories to 500-600 per week (500 for women and 600 for men). The calorie limited days can be on any two days of the week you choose, but must be separated by at least one, non-calorie restricted day.
There are no restrictions as to what foods can be eaten on either type of day, but a healthy, balanced diet is recommended in order to see the best results. This “modified” approach to fasting, by restricting calories to a fourth of daily caloric needs rather than not consuming any calories at all, may make fasting more approachable and easier to stick to for participants while still receiving some fasting benefits.
Benefits often include: Improved insulin sensitivity and hormone levels, weight loss, and reduced inflammation.
Risks: Extreme focus on calorie counting and restriction could lead to unhealthy food relationships.
The Warrior Diet was founded in 2001 by Ori Hofmekler, a former member of the Israeli Special Forces. This approach to intermittent fasting is characterized by the eating patterns of ancient warriors, who ate very little while engaged in battle during the day and then feasted under the safety of darkness each night.
According to Hofmekler, the diet is meant to “improve the way we eat, feel, perform and look,” giving the body a healthy dose of stress through reduced food intake, and thus triggering our innate “survival instincts.”
Participants of the warrior diet restrict food for 20 hours during the day, and then consume one, large, “feast” meal at night. During the 20-hour fasting period, dieters are encouraged to consume small amounts of whole foods like hard-boiled eggs, dairy products, and raw fruits and vegetables, with no limit on non-caloric beverages.
Hofmekler suggests that anyone starting the Warrior Diet should follow an initial three-week plan to “improve the body’s ability to utilize fat for energy.” This plan includes a “Detox”, “High Fat”, and “Concluding Fat Loss” phase that is then to be repeated. More details on Hofmekler’s exact protocol can be found at https://www.healthline.com/nutrition/warrior-diet-guide#how-to-follow
Benefits may include: Followers of the Warrior Diet claim that this method of eating burns fat, improves concentration, boosts energy levels and stimulates cellular repair.
Risks: It is important to note that the Warrior Diet has not been the subject of scientific study and results are anecdotal. Following such a rigorous eating plan may result in binge eating or other unintended disordered eating tendencies.
ALTERNATE DAY FASTING (ADF)
Alternate day fasting is accomplished by fasting every other day. Some choose to consume no calories on their fasting days and drink only water or black coffee, however, the most common approach to this method is to restrict calories to under 500 on “fasting” days. Rather than having to focus on regular calorie restriction every day, alternate day fasting allows participants to simplify their calorie tracking and take a “break” every other day, while still seeing results. ADF has been shown to be particularly effective for weight loss, producing greater fat loss while preserving more muscle compared to traditional, daily calorie restriction.
Benefits often include: Reduced risk of type 2 diabetes, lowered insulin levels, decreased blood pressure, weight loss, and increased muscle tone when paired with exercise.
Risks: Effects of ADF on hunger and related metabolic stress vary by individual. Studies show that consistent adherence to ADF often produces a decrease in hunger, however this may not be the case for everyone and prolonged feelings of hunger may result in metabolic damage.
Unlike intermittent fasting, which is usually confined within a 24 hour period, extended fasting refers to refraining from caloric consumption for over 24 hours and even up to weeks at a time. One study on patients receiving cancer treatment found that a seven day fast resulted in a notable reduction of chemotherapy related side effects like vomiting, diarrhea, fatigue and weakness (source: https://www.nature.com/articles/onc201191). But could there be extended fasting benefits for those who are otherwise healthy?
When it comes to cellular turnover, there is some debate as to when autophagic benefits begin to occur, or how long you actually need to fast before seeing the benefits of autophagy. A few sources claim that cell turnover only begins at the 18 hour fasted mark, meaning some of the methods mentioned earlier such as 16:8 wouldn’t actually produce autophagic benefits.
There’s also the fact that autophagy increases exponentially the longer one fasts, but at some point, the detrimental effects of starvation begin to counteract the benefits of autophagy and should also be taken into account. At some point, the body’s cannibalization turns from unhealthy cells to our necessary bodily components such as muscles and organs and needn’t be taken to that extent, especially when not under the supervision of a medical professional.
Generally, extended fasting is taken on in response to extreme cases of illness, as a very occasional reset for otherwise healthy individuals, or for religious observation.
Benefits often include: Increased autophagy, muscle building, and weight loss; decreased symptoms of hypertension, inflammation, and aging.
Risks: Hormonal fluctuations, disordered eating tendencies, mood swings, hunger, and irritability.
Yoshinori Ohsumi’s discovery of autophagy set off an onslaught of fasting diets with a variety of approaches and promised results. It is important, however, to consider the potential benefits and risks before attempting any fasting protocol. While a more moderate fasting approach may be considered generally safe for healthy individuals, it is important to consult with your doctor before diving into any new pattern of eating.