Fast day eating

Theoretically  you could have a large burger and endless cups of black coffee on a fast day and be within your calorie allowance, but clearly this wouldn’t be at all good for you! Instead, it’s a great idea to use your fasting day to make balanced and healthy choices, using the following guidelines.

Eat five a day

Your fast day is the perfect opportunity to fill up on fruit and veg as these foods are bulky and low in calories, take up plenty of room on your plate (a psychological boost!) and are linked with a lower risk of killer diseases such as heart disease and cancer. Green leafy vegetables such as spinach, kale, watercress, rocket, broccoli and cabbage are particularly low in calories, as are berries such as strawberries, raspberries, blackcurrants and redcurrants, which you’ll often find in convenient form in the freezer section of the supermarket. Tomatoes, peppers, orange-fleshed melons and butternut squash join the low-calorie corner – the wonderful thing about all these richly coloured fruit and veg is they consistently appear in superfood lists because of their high antioxidant content (antioxidants are the component in fruit and veg that mop up the free radicals that can damage our cells).

In short, by using your fast day as a chance to eat at least five colourful portions of fruit and veg a day (a portion is around 80 g/ 3 oz, or roughly a handful), you’ll be boosting your health as well as benefiting your waistline.

Dairy and pulses

These two deserve a special mention because they’re unusual in providing a combination of carbs and protein in one easy package and are a great source of vitamins and minerals. They can be easy on the waistline too – 0% Greek yogurt (a great topping for fruit) has only 57 calories in a 100 g (3½ oz) serving, while creamy canned butter beans (fabulous to bulk out a salad) have 56 calories in a 60 g (2½ oz) serving.

Include lean protein

The lowest calorie lean protein sources (all weighing in at less than 100 calories for a 100 g/3½ oz portion) include prawns, tofu and tuna canned in water, though grilled fish, eggs and chicken breast are also very good choices. Including one or more of these protein foods on a fast day is to be recommended, as you’re more likely to preserve valuable muscle tissue during periods of calorie restriction when protein is consumed (and particularly if you exercise, too). Another big bonus is that protein is particularly good at keeping you full, so can help to keep hunger pangs at bay for longer. Digesting it also uses up more calories than does digesting other nutrients, which is all grist to the mill of your diminishing middle!

Choose quality carbs

Admittedly you won’t be able to eat very big carb portions on a fast day (there are around 100 calories in just one slice of bread, for example), but it’s a good idea to make sure any modest portions you do choose are as unprocessed or nutrient rich as possible, and to focus on higher fibre choice where you can. Wholemeal breads, porridge oats, wholewheat pasta, pearl barley, fortified wholegrain breakfast cereals and potatoes in their skins tend to have a relatively low glycaemic index or GI, which means they raise blood sugar levels only relatively slowly, helping to keep blood sugar, energy and appetite levels more controlled.

Perhaps more important, though, is not to spend too many (if any) of your fast day calories on sweet and sugary carbohydrates, such as biscuits or dessert. (A rough rule of thumb would be for women to use no more than 50 calories on these foods, and men no more than 100 calories.) Quite apart from their lack of nutrient value, they’ll really challenge your ability to stay on track because they can cause your blood sugar levels to fluctuate, heightening feelings of hunger.


  • Concentrate on fruit and veg(steamed, grilled, stir-fried or in soups and salads) as your main stomach-filling priority (up to 200 calories).
  • Use most of the remaining calories (300 or 400) on low GI carbohydrate rich and/or protein-rich foods.
  • Any calories you have left over you can use as you wish . But choosing more nutritious foods is always best.

Drink options

It is important to stay well hydrated on fast days, but with the exception of low-fat milk (or a milk alternative, such as soya milk), many drinks can be a wasteful, non-filling way to spend calories. Your best options on a fast day are calorie-free drinks, such as black coffee and tea (though try not to drink more caffeine than you would normally), herbal teas, diet drinks and of course (and best of all) good old water. To jazz it up, try a sparkling variety and add a squeeze of lime or lemon.

Alcohol is one of the least sensible choices of all (even the smallest glass of wine has around 100 calories and could stimulate your appetite) so use your fast days to abstain from alcohol altogether and give your liver two days a week of much needed rest!


  • The day before your first fast, eat well and aim to go to bed feeling neither hungry nor overfull. Getting an early night is good preparation. Trying to stuff in as much food as late as possible so you don’t feel hungry tomorrow is not!
  • Do your eating home work so that you know how you are going to spend your 500 or 600 calories, and which meals you are going to spread them between. Use the recipes in this app as inspiration and make sure you are stocked up with the requisite ingredients.
  • Try to make your environment as devoid of food temptations as possible, which means ensuring as tray slice of pork pie isn’t the thing screaming, ‘eat me!’ when you open the fridge.
  • Use the calorie counter in this app to get you started.
  • Be aware that choosing a less busy day to start your fasting may not be the best approach. As long as you have your food choices pre-planned, a day with plenty to keep you occupied may be better.
  • If you find your first fast too hard and have to give in, you’ve probably just chosen the wrong day. Don’t despair and try again another time, but leave it a few days.

Fast day feel-full tips

  • Water is the perfect slimline filler, either drunk on its own to temporarily take the edge off a hunger pang or more particularly incorporated within food to increase satiety (the feeling of fullness that food imparts). Chunky soups plus lots of fruit and veg can work particularly well on a fast day because they’ll help to make your stomach feel full.
  • Airy foods take up more space on your plate (so, psychologically it feels like you’re being presented with more food) as well as in your stomach. One study by Professor Barbara Rolls at Pennsylvania State University, published in the journal Appetite, compared the same snack in a puffed and non-puffed version and found that those receiving the airy snack ate 73 per cent more in volume, but consumed 21 per cent fewer calories. Rice cakes are the ultimate airy food, and a whipped mousse (which can have fewer than 80 calories per pot) is the way to go if you really can’t do without dessert!
  • Protein-rich foods are particularly good at inducing satiety. One theory is that they stimulate the release of hunger-controlling hormones in the gut. The protein in eggs seems particularly good at keeping you full, so give them a try!
  • Wholegrain versions of breakfast cereals, breads, pasta, rice and noodles take longer to chew and are more satisfying, as the fibre they contain provides bulk but no calories. Fibre also has a slowing effect on the passage of food through the gut, which has the effect of keeping you fuller for longer. The portion size of bread or pasta you can have on a fast day is small, but choosing a ‘brown’ not ‘white’ version can help to make it more filling.
  • Focus on whole foods. On average, foods that aren’t highly processed, pre-packaged or high in sugar will tend to be lower GI and keep your blood sugar levels on a more even keel.

Don’t estimate!

Building up an accurate picture of what actually constitutes 500 or 600 calories is one of the most educational and interesting aspects of the 5:2 diet. It can help you understand what constitutes a healthy portion and might also give a clue as to why you ended up needing to lose a few pounds in the first place.

It won’t come as a surprise then, that ‘estimates’ and ‘educated guesses’ are definitely not okay when it comes to calculating your fast day calories. With the best will in the world you’ll almost certainly be wrong, which will jeopardize your weight loss and dilute the health benefits. If you’re not convinced, try seeing if you can correctly estimate the ‘recommended’ 30 g (1 oz) serving of flake-style breakfast cereal such as bran flakes. Most people pour nearer to 50–60 g (2–2½ oz) into the bowl, which can add over 100 ‘accidental’ calories and completely destroy a fasting day.

If you don’t own weighing scales and a measuring jug, you need to lay your hands on both. With a basic set of electronic kitchen scales available at relatively low cost, and measuring jugs even cheaper, it doesn’t require a great investment. Make sure you also have some measuring spoons in your kitchen drawer and you’ll be well fixed.

At first, you should weigh everything until you’ve got a clearer idea of what different-sized portions weigh. Your idea of a ‘medium-sized’ apple – 100 g (3½ oz) with peel but no core, according to official publications – may be very different to mine or someone else’s. It’s also important to weigh the ingredients carefully when you’re making

If it seems like a pain, it’s really not – it’s actually quite fun learning about calories and portion sizes and, as you’re only doing it two days a week and you’re not eating terribly much on those days either, it’s not at all onerous. Look at it as a chance to really understand what you are putting into your mouth.


Sugar substitutes, including aspartame, sucralose and more recently stevia, have been approved by the UK government and health authorities the world over, yet there still seems to be a host of scare stories circulating as to how they could actually make us fatter or even cause cancer. In the end it’s up to you if you want to use them or not, but if adding a bit of sweetness to a bowl of berries or to a cup of tea makes you more inclined to stay on track with your 5:2 diet, then go ahead and use them. Unless you’re eating sweeteners in vast quantities they are very unlikely to do any harm and are a much better bet on fast day than spoonfuls of sugar.


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