Celebrity Diets

The Fast (5:2) Diet Review

On this site, many of the popular diets that have been reviewed so far have been created by doctors, nutritionists or other experts in the field with a lot of extensive study. This next one, however, was created by a journalist named Michael Mosley. Back in 2012, Mosley aired a documentary on BBC called “Eat, Fast and Live Longer”. People were immediately interested, and the Fast Diet (also known as the 5:2 Diet) started to gain popularity.

After many people around the United Kingdom were experiencing results that they wanted, the popularity became international. The Fast Diet was being advertised as the new trend sweeping through Europe, catching the interest of many Americans. There have been critics of the Fast Diet, though, and there is plenty you have to know before giving it a try. Let’s take a look at the Fast Diet, and what it entails.

The Basics of the Fast Diet


As the other name (5:2) and primary name would suggest, the Fast Diet does require some fasting, to the tune of five days of normal eating and two days of hard dieting. Some people might think that it means completely fasting for two days without consuming a single calorie, but that isn’t the case. Mosley claims that women on the plan will be able to lose one pound each week, while men could lose one to two pounds.

The two days of fasting require you to eat a quarter of the calories that you normally would. Let’s say, for instance, that you are eating 2,400 calories on most days. This would require you to cut down to 600 for each of the two days. Mosley makes the claim that one expert he talked to said “There is nothing else you can do to your body that is as powerful as fasting.” How the word powerful is used in that quote, though, is a bit of a mystery.

Mosley has also said that the Fast Diet is more of an overall health focus, but weight loss is an added bonus. It might sound a bit hard to believe at first, especially with a lack of extensive medical research, but there are at least plenty of resources available with the Fast Diet. There are several books, trackers and forums with active participants that can help guide you through every step of the way.

What’s on the Menu?


For those five days per week that you are eating normally, you don’t want to go overboard. Especially since you will be eating a quarter of the calories on fast days, and you might end up having fast days that reach the amount of calories that you should be eating just to maintain weight. We used the example of a 2,400 calorie diet (very manageable) for the five normal days, so here is an easy to stick to sample menu of those days:


  • 1 Large Banana
  • 1 ½ Cup of Skim Milk
  • 1 Cup of Cereal


  • 1 Hard Roll
  • 4 Ounces of Chicken Breast
  • 1 Ounce of Cheddar Cheese
  • ¾ Cup of Lettuce
  • 2 Tomato Slices
  • ¾ Cup of Juice
  • 1 Apple


  • 3 Ounces of Pork Chop
  • ½ Boiled Potato
  • ½ Cup of Squash
  • ½ Cup of Green Beans
  • 1 Tablespoon of Margarine


  • Sports Bar
  • 1 Banana
  • 4 Ounces of Lowfat Yogurt

That sounds like a pretty tasty day where you don’t have to starve yourself, and there are plenty of foods that don’t taste too bland. Now, the interesting part comes: the fasting days.

Fasting Days


If you are already at a normal weight, it’s not suggested that you start doing fasting days for now until more research can be done. Some of the other basics include avoiding alcohol on a fast day, as well as carbohydrates. You are going to get about 600 calories on a fasting day, and although you can exercise, it can feel you feeling unwell (especially without any carbohydrates).

The studies that Mosley has done were done with people that were eating one small meal per day. However, the more common approach now that the Fast Diet has become more popular is eating two very small meals instead, while some have even broken it down to three plus a snack. Here is what a sample day looks like when trying to fast in two days per week:


  • 1 Chopped Kiwi (42 Calories)
  • 50 Grams of Blueberries (29 Calories)
  • 3 Tablespoons of Greek Yogurt (24 Calories)

Total = 95 Calories


  • 2 Corn on the Cobs
  • 25 Grams of Butter
  • 1 Shallot
  • 5 Tablespoons of Single Cream
  • 3 Tablespoons of Pumpkin Seeds
  • 1 Small can of Corn

Total = 152 Calories


  • 1 Grilled (Skinless) Chicken Breast
  • 3 Ounces of Green Beans

Total = 213 Calories


  • 14 Raw Almonds

Total = 97 Calories

Daily Total = 557 Calories

Now, you’re probably wondering just how long you have to fast for on these two days. It is not actually 24 hours that you might believe, but instead lasts for 36 hours. With sleep taken into account, it will still fit within your regular eating schedule. If you’re normal dinner time is at 7pm, then you can eat normally once again at 7am two days later.

When it comes to being able to drink, you aren’t confined to just water. Black coffee and tea are basically calorie free, and allowed to be consume on fasting days. Even diet soda counts, as you are just avoiding calories instead of depriving yourself. That means you can still get your caffeine fix while still cutting calories almost completely from your days.

Things to Know


A lot of the diets that we have reviewed are safe for all ages, but it’s not recommended that the Fast Diet be practiced by those under the age of 18, or the elderly. If you are starting to feel sick, then even Mosley says that you should go back to normal eating (or possibly find a more conventional weight loss plan). Also, be able to speak with a doctor before starting on the Fast Diet plan.

As for the side effects, those are to be expected when fasting, especially if you haven’t done it before. A sensation of hunger (even to the point of pain) has been reported by those that have tried the Fast Diet. Feeling faint or woozy, often accompanied with headaches, has also been reported. Mosley says that people should be drinking a lot of water to counteract these side effects, though that probably isn’t the only solution.

This diet is certainly not recommended for diabetics, as crashes in blood sugar on the fasting days are incredibly dangerous. Also, those that have recently had an operation should give themselves at least a month before trying the diet. Make sure to have your blood pressure, cholesterol and pulse monitored throughout the entirety of the Fast Diet to make sure that everything is still in working order.


If you find yourself not losing any weight while on the Fast Diet or have reached your goal weight and want to keep going on the plan, there are alterations you can make. For those that have reached a plateau, some have done four days of normal eating and three of fasting instead of the standard five and two plan. As for maintenance, you can cut it to one day of fasting, which Mosley says will be enough to avoid regaining the lost weight.

Summing it Up


In the world of popular diets, experts have ranked the Fast Diet very low in terms of health and ability to follow. If you’re used to eating 2,400 calories per day, then eating 600 in just one day can be difficult, let alone two days per week. You might get used to it, but it’s still depriving yourself for two days a week and that’s going to be hard to sustain for a long period of time.

For those that want to lose a minor amount of weight quickly, the Fast Diet is certainly not among the worst plans out there. Fasting for two days in a row can be very difficult, so thankfully you can pick two random days out of the week to fast instead. Those that have opted for two separate days have had more long term success.

There are plenty of risks involved with the Fast Diet, and doctors are split on how they feel about the program. While some have condemned the plan altogether due to its lack of daily nutrients while others have claimed it’s a solid weight loss plan that should only be performed by healthy adults. It all comes down to how much willpower you can have on the two fasting days, and how your body responds. There are certainly healthier plans out there, but they may not be as trendy and produce quicker weight loss.