The 5:2 diet originated in the United Kingdom in the 2010s and was popularized by Micheal Mosley, a medical journalist. As a form of intermittent fasting, the diet involves restricting calories for two days of the week.
Followers of the plan can eat what they like for the remaining five days, and there is no need to restrict or monitor calories on these days. The plan allows an unlimited choice of foods and drinks on all days of the plan, so patients are in complete control of what they eat and can choose foods they enjoy.
Since the plan only requires calorie restriction for two days, some individuals find the 5:2 diet is easier to maintain than traditional diets that require daily calorie restriction.
Of course, patients should always check with their doctor before beginning any type of diet or fasting program to ensure they can complete the program safely.
The guide below discusses the basics of the 5:2 diet and provides information on the benefits and risks of this eating plan.
Intermittent Fasting Basics
As the name suggests, intermittent fasting involves fasting for a short period. Some of the most popular intermittent fasting approaches involve simply confining eating times to a set number of hours per day.
For example, patients might choose to fast for sixteen hours of the day and consume all of their food within an eight-hour timeframe. This method is often used by individuals who are new to intermittent fasting.
As individuals become more comfortable with this eating method, they may decide to have a smaller eating window; common approaches ask the patient to consume all of their meals within six hours while fasting for eighteen hours, and some patients choose to allow themselves a four-hour eating window with a twenty-hour fast.
During the eating window, the patient eats all of their meals as normal; there is no requirement to count calories or to change the patient’s regular diet in any way. Rather, the patient simply eats as they normally would, and the meals are consumed within a set number of hours.
To make the fasting hours easier, many patients start by fasting overnight and eating breakfast a few hours later in the day than they otherwise might.
They can then restrict their eating window more after adjusting to this. It is typically advised that no food is consumed during the fasting periods, though patients are allowed to drink unlimited water, herbal tea, and other calorie-free beverages.
An advanced variation of intermittent fasting involves a total fast (with no food) for twenty-four hours on two or three days of the week, and the patient follows their normal eating pattern on the remaining days.
How The 5:2 Diet Works
The 5:2 diet is considered a modified form of intermittent fasting. Instead of going without food entirely during the fasting times, the plan allows for the consumption of a limited number of calories within the fasting window.
This feature often makes it easier for patients to continue as a long-term lifestyle choice. The program allows the patient to choose which days of the week they can fast, and many appreciate this flexibility.
If a last-minute party or dinner invitation arrives, the patient can move their fasting day to another day of the week. Experts suggest beginners on the 5:2 program consider fasting on Mondays and Thursdays.
By choosing these days for fasting, the patient can eat normally for two or three days before each fasting day, and this typically makes the fasts easier to complete.
The two days of the week the patient chooses to fast should be non-consecutive days, as fasting for more than twenty-four hours at a time is not recommended without medical supervision.
Eating on Fasting Days
On fasting days, women are to consume no more than five hundred calories, and men are restricted to six hundred calories.
Patients do not need to restrict their eating window to specific times on the fasting days; they can eat at their normal mealtimes, and having a late dinner or an evening snack is perfectly acceptable.
To make the fast as easy as possible, followers of the 5:2 plan are encouraged to eat several small meals throughout the day. Online cookbooks designed specifically for the 5:2 plan have recipe suggestions for fasting days, and patients can use any recipes that fall within the calorie limit for these days.
Some find it easiest to use packaged foods that display the calorie content on fasting days, and others choose to include meal replacement bars or shakes for some meals on the fasting days.
Building meals around whole grains, fruits, and vegetables enables followers to enjoy a larger quantity of food while remaining within the calorie limits, and this can help ease hunger.
For example, breakfast could include a small fruit salad or a portion of oatmeal with some yogurt, or patients might want to have a piece of wholegrain toast with avocado slices.
Including a large tossed salad at lunches and dinners is ideal, and patients should measure out the salad dressing for calorie control. If planned correctly, fasting days can include desserts as well.
Health Benefits of The 5:2 Diet
Studies show intermittent fasting methods like the 5:2 diet are often associated with significant weight loss and improved metabolic health.
A review of several studies conducted in animals concluded that intermittent fasting reduced both fat tissue and fat-storing cells, and a 2018 meta-analysis found this type of fasting is just as effective as traditional calorie restriction for weight loss and health improvements.
Research suggests intermittent fasting approaches like the 5:2 plan is ideal for reducing the risk of type 2 diabetes.
In clinical studies, participants who follow intermittent fasting programs have been able to reduce their blood glucose readings and insulin resistance. When insulin resistance is reduced, the body is more sensitive to insulin and can use it more effectively.
A three-month study of normal-weight and overweight individuals found that intermittent fasting reduced triglycerides by twenty percent, and levels of an inflammatory marker called CRP were reduced as well.
Notably, the study concluded participants who fasted were able to decrease their levels of leptin (a hormone produced by fat cells) by forty percent. Additional research suggests intermittent fasting may reduce symptoms associated with asthma, seasonal allergies, menopause, and irregular heart rhythms.
Risks of The 5:2 Diet
Although the 5:2 diet is safe for many individuals, it does carry some risks. Doctors advise that it not be used by patients who have a history of eating disorders such as anorexia and bulimia, and it is not appropriate for those with a history of nutrient deficiencies or malnourishment.
Women who are pregnant or breastfeeding should not use the 5:2 diet, and it is not intended for children or teenagers.
Patients with type 1 diabetes are cautioned to avoid all types of intermittent fasting since it could interfere with their blood glucose and medication, and anyone who experiences frequent episodes of low blood sugar is advised to choose a different dietary approach.
Some female patients who try intermittent fasting routines experience changes in their menstrual periods, and menstruation could stop during the program.
Women should consult their doctor before starting intermittent fasting, and they should inform medical personnel if they experience any issues with menstruation.