The 5:2 diet is a form of intermittent fasting. Stated simply, the guidelines for this diet involve eating normally on five days of the week, and fasting for the other two. For the two fasting days, the recommendation is to restrict your caloric intake to 500 calories for women or 600 calories for men. Essentially, the aim is to create a calorie deficit over the seven day period, with the goal of gradual weight loss.
Intermittent fasting has been practiced for centuries, across many cultures with a number of variations in the ratio between eating and fasting periods. The 5:2 diet principles were popularized by British Doctor and Journalist, Michael Mosely, who wrote the original 5:2 diet book in 2013. Over recent years it has been a popular choice as a weight loss focused diet.
Benefits of the 5:2 diet
A number of studies have highlighted the benefits of intermittent fasting, including improved insulin sensitivity, reduced risk for cardiovascular disease, better outcomes for diseases such as diabetes and heart disease[i], benefits for brain function[ii], and improved body composition[iii]. It’s important to recognize that there are limited studies specific to the 5:2 diet. The results obtained from a different fasting method shouldn’t automatically be attributed to the 5:2 approach.
Some small scale studies have compared the benefits of intermittent fasting regimes to a daily energy restriction approach, with mixed results. One study of overweight women reported superior results for insulin sensitivity and body fat reduction in two intermittent energy and carbohydrate restriction groups. This was opposed to a daily energy restriction group[iv].
Another study on overweight women found that intermittent energy restriction produced similar results to continuous energy restriction. Both groups received similar benefits for weight loss, insulin sensitivity and other health biomarkers[vii].
Conversely, a small study of obese women found that regular eating intervals had a beneficial effect on lipid profile, thermogenesis and insulin sensitivity as opposed to an irregular eating pattern[viii].
Most diets and approaches to eating have several associated merits. The key to success is finding out what’s really going to work for you, and whether it’s something you can sustain in the long term.
Points to consider before trying out the 5:2 diet
- As mentioned, the guidelines behind the 5:2 diet recommend eating “normally” for five days of the week. In reality, you might eat a little more than usual to make up for your fasting days. This may still result in a weekly calorie deficit required for weight loss. However, some people on this diet may take to having an absolute “feast” for the five days. If you see the five days as an opportunity to binge on anything you like, you probably won’t create the calorie deficit you need to achieve your weight loss goals. Additionally, consider how these food choices impact your health.
- It’s likely that you’ll feel crappy on your fasting days early on. Although it’s probable that this will improve over time, you may experience symptoms such as dizziness, headaches, fatigue and lack of concentration. Symptoms vary based on individual differences and also food choices, activity and hydration on these days.
- Do you have a long history of dieting, and would you consider yourself to have an unhealthy relationship with food? Some people find that the 5:2 diet seems like less of a “diet” because there aren’t restrictions around what to eat. However, depending on your relationship with food you might feel like you’re seriously depriving yourself on your fasting days. Therefore, you need to consider whether it makes your overall approach to eating better, or worse.
- Avoid the 5:2 diet if you are pregnant or breast feeding, diabetic, a teenager, or an athlete. If you have a health condition, check with your health practitioner regarding the safety of the diet for you.
Best practices to follow on the 5:2 diet
If you’ve decided that the 5:2 diet works for your personal goals and individual preferences, or you just want to experiment, there are some guidelines to increase your chances of success on the diet.
Planning and preparation
- Plan for your fasting days to coincide with rest days from exercise. Your performance will likely be inhibited and you could be placing your health at risk by choosing to exercise on fasting days. You may adapt to the diet over time and tolerate exercise on fasting days. Just err on the side of caution in the beginning.
- Consider the spacing of your fasting days. Aim to have two days of normal eating in between your fasting days. This helps to space them out as much as possible.
- Take some time to consider barriers that might arise on your fasting days. What happens if a social event pops up on those days? How will you cope if there’s food involved and you “can’t” eat any of it? Will you feel resentful or take the enjoyment out of the event? Will you struggle with willpower and end up giving in to the food on offer? If these possibilities ring true for you, plan in advance to change one of your fasting days for the week What effect will that have on your ability to settle into a routine with the 5:2 diet plan?
Managing your food choices
- Although there are no food restrictions, it’s important to consider what to eat on the 5:2 diet, especially on your fasting days. Making food choices that help to curb your hunger pangs and keep you hydrated help to minimize the negative side effects you might experience from fasting. Find out more about what to eat on the 5:2 diet in the next section.
- Find out what approach to fasting works best for you. Do you feel better when you eat a small breakfast to kick-start your day, or do you find it better to start eating as late as possible?
- Do you prefer to have three small meals per day, or two slightly larger meals, or one meal that is larger again?
- It is essential that you stay hydrated, especially on fasting days. This will help curb your appetite and reduce the likelihood of undesirable fasting symptoms. Try out different types of low or zero calorie drink options including infused water, soda water and herbal teas (but skip the zero calorie soft drinks!)
- Don’t panic if you go slightly over your calorie allowance from time to time. It’s not an exact science.
- Give yourself time to get used to the 5:2 diet. Be a curious participant and gradually start to learn the difference between emotional eating and genuine hunger. The 5:2 diet should get easier over time. If it doesn’t, it might not be the right fit for you.
- Once you reach your weight loss goals from following the 5:2 diet, you might choose to experiment with a 6:1 method for maintenance of results
What to eat on the 5:2 diet
You can eat any foods you want on your fasting days but it pays to choose wisely. The following types of foods will help you to feel naturally full without taking on too many calories:
- Low calorie soups and bone broths, especially in the winter. These can help provide much needed nutrients and can assist with hydration at the same time
- Leafy green salads in the summertime
- Plenty of vegetables, especially leafy greens which provide fiber and nutrients
- Choose healthy protein sources such as eggs, lean meat or fish. The protein will help with satiation so you can feel fuller for longer
- Aim to avoid or restrict processed carbohydrates such as bread and pasta. These may leave you feeling hungrier and could make it harder for you to stay under the 500 or 600 calorie limit for the day
- Although foods that contain high amounts of fat will help you to feel fuller, they will quickly increase your overall calorie intake. As a whole, aim to focus on small servings of lean protein and plenty of low calorie vegetables
- If you feel like something sweet on your fasting days, go for some fresh berries or a small piece of fruit as a low calorie sweet option
- Adding a little “zing” to your salads or water by the way of apple cider vinegar or fresh lemon or lime may also help curb cravings
Refer to a food calorie reference table to find out how many calories are in common foods. A number of healthy eating or dieting apps can also provide this information for you.
For additional information on fasting, various types of fast, how to prep and refuel a fast, check out the 131 Method.