The 5:2 Fasting Diet, or simply the Fast Diet, has become one of the most popular ways of using intermittent fasting as a way of controlling or even reversing Type 2 Diabetes.
The diet was popularised by Dr. Michael Moseley, a BBC journalist, presenter and producer. He has written a number of related books including the 8 week Blood Sugar Diet.
It is called the 5:2 Diet because you eat normally for 5 days and then eat a calorie restricted diet of between 500-600 calories on the other 2 days.
Sounds simple but what exactly does it involve?
The 5:2 diet is actually very simple to follow.
It involves eating normally for 5 days a week without worrying about counting calories.
On the other 2 days you simply restrict your calorie intake to around a quarter of your normal intake. That is around 500 calories per day for women and 600 calories per day for men.
You choose which 2 days you reduce your calorie intake but Monday and Thursday is a common pattern.
It is important to understand that eating normally doesn’t mean you can eat anything you like. Binging on fast food, burgers and chips isn’t going to help control your blood sugar or help you lose weight. In fact, you may even gain weight!
So, eat your normal low-carb or paleo or other diet (whatever diet you follow) normally and then reduce the portion sizes on the 2 fasting days. If you aren’t sure where to start, I recommend the 8 week Blood Sugar Diet as a good basis.
What are the benefits? – Will it improve my health?
While there are few studies of the health benefits of the 5:2 diet itself, there have been numerous studies into the health benefits of intermittent fasting in general. These have shown impressive results.
One important benefit is that people seem to be able to stick to the diet much more easily than a calorie-controlled diet.
Several studies have shown that intermittent fasting reduces insulin levels and one study showed that the 5:2 diet produced similar weight loss to a calorie-controlled diet. The results from this last study showed a reduction in insulin levels as well as an increase in insulin sensitivity. Good news if you are Type 2 diabetic!
A further alternative to the 5:2 diet is the 4:3 diet or modified alternate-day fasting. This diet is shown to have several health benefits and may reduce insulin resistance, asthma, seasonal allergies, heart arrhythmias, menopausal hot flashes and more
In a randomized controlled study in both normal-weight and overweight individuals results showed major improvements in the group doing 4:3 fasting, compared to the control group that ate normally.
After 12 weeks, the study showed that the fasting group had:
- Reduced body weight by more than 11 pounds (5 kg).
- Reduced fat mass by 7.7 pounds (3.5 kg), with no change in muscle mass.
- Reduced blood levels of triglycerides by 20%.
- Increased LDL particle size, which is a good thing.
- Reduced levels of CRP, an important marker of inflammation.
- Decreased levels of leptin by up to 40%.
The 5:2 (4:3) Diet – will I lose weight?
If you need (or want) to lose weight then the 5:2 Diet, if done right, is very effective. This is because you consume fewer calories on the fasting days.
It is important, though, not to compensate for the fasting days by consuming more calories on the non-fasting days. If you were to consume the same number of calories per week on the 5:2 diet (or any intermittent fasting diet come to that) as you would on a normal calorie-controlled diet, the weight loss would be the same.
Having said that, fasting diets like the 5:2 Diet have shown a lot of promise in weight-loss studies.
A recent report showed that intermittent fasting lead to weight l- loss of between 3% and 8% over a 3-24 week period. Participants lost 4%-7% off their waist measurements meaning that they lost a lot of harmful belly fat. Intermittent fasting also showed a reduced loss of muscle mass compared to a normal calorie-controlled diet.
Intermittent fasting is also more effective if combined with exercise such as strength or endurance training.
Fasting Days – how should I eat?
There are no hard and fast rules about what or when you should eat on fasting days.
Some people like to start the day with a small breakfast. Others find it best to start eating later in the day.
Most people follow one of two eating patterns on their fasting days:
- Three small meals – breakfast, lunch and dinner
- Two larger meals – just lunch and dinner
As your calorie intake is limited to 500 for women and 600 for men, make sure you use your calorie allowance wisely.
Try focussing on nutritious, high fibre, high protein foods that make you feel full without having too many calories. Soups are a great way to feel more full than the same foods in their original form. You could also try yogurt with berries, eggs, a generous portion of vegetables, fish or lean meat. The 8 week Blood Sugar Diet has some great ideas for healthy and nutritious meals.
What if I feel unwell – or uncontrollably hungry?
To begin with it is normal to feel uncontrollably hungry on fast days. You might also feel weaker and slower than usual.
Don’t be disheartened though. You will be surprised at how quickly this usually passes as your body adjusts. It might be a good idea to have a low-calorie snack to hand though, just in case you need it for the first few fasting days.
If you repeatedly feel faint or unwell, have something to eat and drink and consult your doctor. Not everyone is suited to fasting and some people are simply unable to tolerate it.
Are there people who should avoid the 5:2 diet – Is it safe?
Generally, intermittent fasting is very safe for most people as long as they are relatively healthy and are well-nourished although as I have already mentioned, fasting isn’t suitable for everyone.
There are certain groups who should avoid it altogether though. These include:
- Individuals with a history of eating disorders
- Individuals who are prone to a drop in blood sugar levels
- Women who are pregnant and nursing mothers
- Teenagers and children
- People with Type 1 diabetes
- People who are underweight, malnourished or have a nutrient deficiency
- Women trying to conceive or who have fertility issues
Some women report that their menstrual period stopped during fasting but restarted again when they returned to normal eating. Intermittent fasting may not be as beneficial for some women as it is for men.
Women should therefore practice caution when fasting and stop immediately if any adverse effects occur.
One final word
The 5:2 diet is an easy, effective way to lose weight and increase health. Many people find it easier to stick to than a calorie-controlled diet.
If you are looking to lose weight and improve your health, the 5:2 diet is definitely worth considering.
As always, please consult your doctor or other health professional before starting this or any other diet.