Intermittent fasting is any diet that includes regular periods of not eating, or fasting.
This article will explain the 5:2 diet and give a basic example of how to eat on each type of day.
What is the 5:2 diet?
The 5:2 diet is a type of intermittent fasting.
The 5:2 diet gets its name because it involves eating regularly for 5 days of the week while drastically limiting caloric intake on the other 2 two days.
While the 5:2 diet is a popular form of intermittent fasting, the term fasting is slightly misleading.
Unlike a true fast, which involves eating nothing for a set amount of time, the goal of the 5:2 diet is to cut caloric intake on fasting days to 25 percent or just one-quarter of a person's regular intake on the remaining days.
For example, a person who regularly eats about 2,000 calories per day would eat 500 calories on fasting days.
Importantly, fasting days are not consecutive because it is vital to give the body the calories and nutrients it needs to thrive.
People typically space their fasting days out, for example, by taking their reduced-calorie days on Monday and Thursday or Wednesday and Saturday.
Part of the diet's appeal is this flexibility. Instead of severely restricting the foods a person can eat, the 5:2 diet focuses on strict caloric restriction on only 2 days of the week. This may help some people feel more satisfied with their diet, as they will not feel that they are missing out all the time.
The 5 normal days of the 5:2 diet should still involve a healthful diet, however. Loading up on sugary or processed foods for 5 days and then having a small break may not be as helpful as keeping a trend of clean eating during the entire week.
What are the benefits?
The 5:2 diet can have several benefits, including:
For the most part, people who follow the 5:2 diet plan are looking to lose weight.
To lose weight, a person typically needs to eat fewer calories than they burn. Nutritionists call this a caloric deficit.
When someone follows this correctly, the 5:2 diet may be a simple, straightforward way to cut calories, which may help burn extra fat.
While there are not many studies on the 5:2 diet specifically, initial studies on intermittent fasting seem promising.
A review in the Annual Review of Nutrition noted that in animal studies, a similar intermittent fasting diet led to a reduction in fat tissue and the cells that store fat.
A 2018 review and meta-analysis compared intermittent fasting to simple calorie restriction diets. This research noted that intermittent fasting is as effective as calorie restriction when it comes to weight loss and improving metabolic health.
Reducing the risk of type 2 diabetes
Initial studies also suggest an intermittent calorie diet may also help reduce the risk of diabetes in some people.
Research from 2014 suggests that both intermittent fasting diets and calorie restriction diets helped reduce fasting insulin levels and insulin resistance in adults who were overweight or obese. The reviewers did call for more research to confirm these findings.
This does not suggest that intermittent fasting is a better diet, just an equally effective alternative for people who find calorie restriction diets difficult.
How to eat on fast days
Some people choose to eat small meals throughout the day.
There is no correct way to eat on fasting days, as each person's body may respond differently to fasting. The principle is that on fast days, a person consumes just 25 percent of their normal calorie intake.
For instance, some people may need to start the day with a small breakfast to get their body moving. For others, eating breakfast immediately may make them feel hungrier throughout the day. These people may want to wait as long as possible before having their first meal.
Because of this, everyone's meal plan may look slightly different. Some fast day meal schedules include:
- eating three small meals such as an early breakfast, afternoon lunch, and late dinner
- eating an early lunch and dinner
- eating a small breakfast and late lunch and skipping dinner
- eating a single meal at dinner or breakfast
The main focus of these days is for a person to drastically reduce the calories they eat.
If an individual regularly eats 2,000 calories per day, they should only consume 500 calories on fast days.
A person who usually eats 1,800 calories a day should reduce their intake to 450 calories on fast days.
Foods to include
It is vital to keep the body satisfied on fast days by eating foods that are rich in filling nutrients, such as fiber and protein.
Vegetables and fiber
For people who are just getting started on the 5:2 regimen, eating more vegetables may help them feel as if they are not lacking during a meal. Vegetables can be very low in calories compared with animal products and grains, meaning more vegetables can fit into a small meal.
Dark, leafy greens and salads can be a great way to add bulk to a meal and help people feel fuller without eating extra calories.
Another example of this is to use a spiralizer to turn zucchini or carrots into noodles, making a low-calorie base for a sauce as an accompaniment.
Protein is vital for staying full during fast days. People should focus on lean sources of protein without too much fat.
Add small portions of lean forms of protein on fast days, including:
- white fish
- lean animal cuts
- beans, peas, and lentils
Importantly, people can avoid extra oil and fats by boiling, grilling, or roasting these foods instead of frying.
While most fruits are rich in natural sugars, dark berries, such as blackberries and blueberries, may fulfill sweet cravings without adding many calories.
Other foods to include
- Soup: Soup is a great tool for fast days, as the added water and spices from the broth may help a person feel more satisfied without eating too many calories.
- Water: Water is vital every day, but during fast days it may help stretch the time between meals and keep a person from feeling hunger pangs.
- Coffee or tea: Plain, unsweetened coffee and tea are acceptable during fast days. However, some people find that coffee or tea stimulates their digestive system, making them feel hungry. Herbal tea is another option and is a great way to increase the person's water intake.
Foods to avoid
To avoid extra calories or using up the daily calorie limit on foods with fewer nutritional benefits than some other, more nutrient-dense ones, a person may wish to avoid the following foods on fast days:
- processed foods, which are typically refined and high in calories
- refined carbohydrates, such as breads, pastas, and white rice
- excess fats, including cooking oils, animal fats, and cheese
Examples of meals on fast days
Vegetable soup is a meal option for fast days.
Examples of smaller meals for fast days include:
- a generous portion of steamed vegetables with spices and salt
- vegetable soup
- two hard-boiled eggs
- a small cut of steamed white fish
- a generous portion of salad with fresh vegetables
How to eat on regular days
On regular days, a person eats as they usually would. It is essential to note that these 5 regular days are not "cheat days." For this reason, it is still helpful to stay within the recommended calorie limit and eat a variety of nutritious foods.
A person who eats lots of processed, packaged, or unhealthful foods will likely notice less change in their weight from fasting.
Is the 5:2 safe for everyone?
The 5:2 diet may be a helpful alternative to some people looking for a less restrictive diet plan, but it is not for everyone.
People who are prone to low blood sugar or easily feel dizzy or fatigued if they do not eat may not want to follow a diet that involves fasting.
Pregnant or breastfeeding women must also avoid fasting. Children and teenagers should avoid fasting unless under the direct guidance of a doctor, as their bodies are still developing.
Anyone with a chronic condition, such as diabetes, can consult a doctor before trying any diet that includes fasting.
The 5:2 diet offers people an alternative to basic calorie restriction, which could help many people stick to their diet and lose weight.
Fasting days can take some time to get used to. Hunger pangs or feeling faint may be more common when a person is beginning a 5:2 diet than when they are used to the regimen. Many people who continue the diet say these effects lessen as their body adjusts.
Some people should not do this type of diet, however. Anyone who is uncertain about their specific dietary needs should consult their doctor or dietitian before starting the 5:2 diet.