Intermittent fasting or the ‘5:2’ diet has become popular over the last 6 months and I am asked about it regularly. While there are a few variations of this diet plan, most involve having two non-consecutive days a week fasting (consuming just 500 calories). You can spread your meals and food intake however you like on the fasting days, as long as you stick to under 500 calories. The other 5 days involve eating a balanced healthy diet. The reported benefits include weight loss, reduced cardiovascular disease, lowered blood pressure and better blood sugar regulation. There is also a lot of research that shows that caloric restriction in any form followed long term extends lifespan by as much as 10-15 years.
Ultimately, anything that encourages caloric restriction will lead to weight loss, but is this a healthy way to do it?
500 calories a day
Firstly, what exactly can you eat on the fasting days? 500 calories a day is not very much! Here are some examples. I have tried to keep the protein content of these examples higher than much that you will find online to ensure metabolic rate does not drop, however many of the recommendations involve eating vegetables, salads and crispbread only. Remember that drinks such as coffee and juice contain calories as well. You can have water and black tea without sugar as well as herbal teas, however all other drinks need to be calculated as part of your 500 calories (for example, a cappuccino made with regular milk and no sugar has around 130 calories).
Breakfast- Burgen bread (soy and linseed) x1 with 1 hard boiled egg (no butter)
Lunch- 2 ryvita crispbread with tomato, alfalfa, cucumber
Dinner- Vegetable stir fry (mushroom, broccoli, capsicum, spinach, snow peas 1 cup) with 80g of lean chicken breast.
Breakfast- 1/2 a banana on 2 ryvita crackers
Lunch- 1 hard boiled egg with salad (cos lettuce, tomato, cucumber, mushrooms, olives)
Dinner- Half a fillet of salmon, baked with broccoli, beans and asparagus
Breakfast- 1 burgen toast with vegemite
Lunch- 1 cup (raw) steamed low calorie vegetables (broccoli, snow peas, zucchini, asparagus) and 1 tin of tuna (brine drained)
Dinner- 1 cup of homemade vegetable soup
The Pros of intermittent fasting
– Intermittant fasting does help for us to learn to be ‘ok’ with feeling hungry. For many, feeling hungry can make us feel panicked, anxious and uncomfortable. Periods of fasting is something that we are not used to with our standard western regime of 3 main meals and 2 snacks. However, these feelings are completely normal and act as a survival instinct to get us ready to find our next meal. Including a couple of days of ‘fasting’ helps us to feel at ease with our appetite and realise that it is ok to be hungry.
– It helps us to break unhealthy eating habits, such as afternoon sugar hits, morning coffee and after dinner chocolate. These will simply not fit into a 500 calorie a day plan.
– It takes discipline and will give a sense of achievement knowing that you got through a fasting day. For most, this will leave you more determined to continue healthy eating.
– Studies show that fasting for 2 days a week with no calorie restriction on the other 5 days leads to equal weight loss results to those diets that involve daily calorie restriction. For some, having 2 days a week of feeling deprived may be better than having to watch what you eat every day.
Cons for intermittent fasting
– Let’s face it- it’s not enjoyable to starve yourself. Eating should be a pleasurable experience and something that we look forward to. Cutting food intake down to 500 calories is very restrictive and difficult to follow. In fact, many studies have found that long term compliance of this diet method is poor.
– Side effects such as irritability, tiredness, lack of concentration, anxiety and dehydration can occur on the fasting days. I myself know that I would find it difficult to get through a work day with such a low calorie intake.
– Restrictive eating such as this can set up negative associations with food as well as ‘binge eating’ on the free days. This program will not work for those who eat unhealthy or increase portion sizes on the other days.
– I have read various publications stating that you can eat ‘whatever you want’ on the non-fasting days. Hopefully common sense will prevail for most and they will continue with a balance, healthy eating plan on their free days. Healthy eating is not just about calorie intake and we need to ensure that we are getting a good spread of our macronutrients (carbohydrates, fats, sugars) and micronutrients (vitamins, minerals) on the other days. We simply can’t reach the RDI of many nutrients on the fasting days with such a low calories.
Who should not undertake an intermittant fasting eating plan?
Pregnant women, or those trying to conceive. Diabetics, or people prone to hypoglycaemia. Athletes or people with high exercise. Children. Anyone trying to gain weight.
As with any ‘diet’ this plan will work for some and not for others. Ultimately, I do not think it is sustainable to stick to this way of eating long term. A healthy eating plan that is able to be maintained for life is the healthiest way to eat. However, I do think this is a useful plan to follow in the short term for those who have hit a weight loss plateau. As with anything, you do something long enough and the body adapts. This happens all the time with weight loss and it is inevitable that after you have followed a diet regime for long enough, weight loss will slow as your body adjusts. Here is when you need to either ramp up the exercise or further restrict food intake. Increasing exercise is a healthier long term option, but for some people there is just not enough time in the week to get the exercise done. Intermittent fasting would be useful in these cases to kick-start weight loss.
Patients- please remember to consult with me first before embarking on intermittent fasting!
Yours in Better Health