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What is the 5:2 diet and does it work

Two bowls of green soup
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What is the 5:2 diet?

Made famous by Michael Mosley, a doctor and science journalist, following a feature in his BBC documentary, the 5:2 diet is based on intermittent fasting. The idea is that you restrict your calories to 500 for women and 600 for men, for two days a week and the other five days you eat a normal healthy diet. Typically men need 2400kcals a day and women need 2000kcals a day, however on the fasting days you will only have a quarter of your usual allowance.

This fasting diet allows you to reduce the amount you eat but only for short periods of time, making it more sustainable in the long term. The days that you are not fasting you will need to be physically active and still eat within your daily calorie limit, as to not cancel out the days that you have fasted.

How does intermittent fasting work?

Fasting works by cutting down the amount of calories you eat by cutting down the amount of time you end up eating, for example instead of eating three times a day you may only eat two full meals a day. During your fasting days you are limited to a set number of calories, when you are not fasting you should eat the same as you normally would and not aim to replace the calories you didn’t eat yesterday.

Also during a fast your body goes into a fasting state, where it looks to break down any energy that it can. As you are not giving your body energy in the form of food, it looks for energy that has been stored away as fat, thus breaking down your body fat.

What to eat on the 5:2 diet

On the days that you are fasting your calorie intake will be limited, if you’re a man this will be to 600kcals and if you’re a woman your allowance will be 500kcals. To alter your current eating habits to fit in with the 5:2 diet you may have to research, adapt and tweak some of your current recipes, for example swapping products for low fat alternatives or choosing leaner cuts of meats can help you to reduce your calorie intake.

500 calories a day meal plan

A typical fasting day diet plan could be:

  • Breakfast – 40g porridge oats made up with water, poached eggs with spinach or low fat natural yoghurt with a banana
  • Lunch or dinner – mushroom omelette, roasted vegetables, soup or chicken with cous cous

Make sure to check food labels to find out how many calories there are per serving. You can also use the NHS calorie checker tool.

If you want to use all for your 500 calories in one meal, or if you are looking for a lighter calorie option then there are complete meals that you can have. From paella to spaghetti, tuna salad to turkey burgers, there are plenty of 500 calorie meals to choose from and create.

How much weight can you lose on the 5:2 diet?

Losing too much weight too quickly can be unhealthy, so the target for any sustainable weight loss diet should be gradual weight loss. With the 5:2 diet, participants can expect to lose anything from a few pounds to a few stone over time. This will entirely depend on your weight when you first begin and other aspects such as how much you’re exercising during normal calorie intake days.

Typically, weight loss tends to occur more rapidly at the beginning of your diet before tapering off. Everybody is different, so don’t be disheartened if you’re not losing as much weight as other people who started the diet at the same time as you.

Is the 5:2 diet sustainable?

Sticking to a diet plan for two days a week as opposed to seven is more achievable than attempting a full week. As with everything, new habits require time to form. If you’re struggling to fit the diet around your lifestyle at the beginning, you may still find it easier later on if you stick with it. With that being said, the following side effects may impact the sustainability of the 5:2 diet:

  • Daytime tiredness
  • Trouble falling asleep
  • Irritability and anxiety
  • Dehydration
  • Bad breath – sometimes a result of low carbohydrate diets

On fasting days, you’re likely to have less energy and your ability to carry out your normal tasks (job, family life etc.) will be impacted. Whilst there is evidence to support the benefits of a 5:2 diet, it’s somewhat limited so it’s always best to check in with you GP before starting and to follow any recommendations to stop.

Is fasting a good way to lose weight?

The 5:2 diet plan aims for a weight loss of 1lb a week for women, and for men you could expect to lose slightly more. The NHS recommend a loss of 1-2lbs a week for healthy and safe weight loss, this amount is also more sustainable.

What does fasting feel like?

On your fasting days you may feel hungrier throughout the day, and have less energy. This could mean you feel tired and that you difficulty concentrating. If you’re thinking of stating an intermittent fasting diet you may want to talk to GP first to make sure that it is safe for you to do so.

Can you drink water when you fast?

Yes, when following the 5:2 diet it is important that you stay hydrated. Water has no calories, making it the best drink choice whether you’re on a fast day or not.

Who shouldn't follow the 5:2 diet?

If you are under 18, pregnant, or have a pre-existing medical condition such as diabetes, then it is not recommended that you follow a diet that requires you to fast. If you want to lose weight speak to your pharmacist or GP who will be able to advise you, also read our how to lose weight healthily page

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