Intermittent Fasting for Weight Maintenance?

Here at Slim & Save, we first and foremost recommend a healthy balanced diet for maintenance after completing a Slim & Save programme. Our dietitian has developed some calorie controlled plans for those of you who would find these useful. However, we are aware that many of you manage your weight maintenance through following some form of intermittent fasting plan, e.g. 5:2. This article aims to provide a summary of the evidence for the use of intermittent fasting diets and highlight how you should follow them safety if you choose this approach. Moreover, we hope that this article will give you the information to empower you to decide the most appropriate approach you might take with regards to weight maintenance. After all, one size doesn’t fit all when it comes to nutrition.

What are intermittent fasting diets?

‘Intermittent fasting’ is the term given to diets where you have some form of ‘fasting’ interspersed with more ‘normal’ eating. Whilst most approaches require you to restrict intake of calories for a number of days a week, and eat ‘normally’ on the other days (e.g the 5:2 approach requires calorie restriction on two days and more ‘normal’ eating on the other five days), a simple internet search will reveal the breadth and variation of approaches to intermittent fasting.

Is there any evidence supporting the use of intermittent fasting diets for weight maintenance?

In short, there is no scientific evidence specifically support intermittent fasting for weight maintenance. The scientific evidence using human studies has focussed on the use of intermittent fasting (e.g. the 5:2 diet) as a method of weight loss. Studies involving this approach have focussed on a specific population of overweight women at risk of breast cancer, who followed a 600kcal diet for two consecutive days, while eating a Mediterranean diet for the remaining five days with some success. Many other recent studies looking at this approach have used animal models, which cannot be translated into human results.

Should I follow this approach for weight maintenance?

As previously mentioned, the best way to maintain your weight (and prevent weight gain) is to follow a healthy balanced diet with plenty of exercise. However, if you struggle to eat healthily the majority of time, a modified version of this approach may be useful for you to try. We have outlined some pros and cons to following an intermittent fasting approach below. It’s important to consider that fasting is not safe for everyone, such as diabetics on insulin or certain medication, so it’s best to consult your GP before embarking on such a diet.


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  • By creating a calorie deficit on the fasting days, it may enable you to manage your diet better and feel more in control, e.g. have treat foods or slightly larger portions on non-fasting days
  • You can adjust your calorie intake on fasting and non-fasting days to suit your particular needs, e.g. if you find you have gained weight, you can reduce your intake, and if you still need to lose some weight, you could try this approach to lose weight too


  • Following a severe calorie restriction on fasting days may leave you feeling exhausted and irritable, making this approach difficult to stick to for some people. Other side effects like sleep difficulties and anxiety have been reported, but there is only anecdotal evidence to support these
  • This approach needs to be planned carefully to ensure you’re not missing out on important micronutrients such as calcium and iron.
  • You may find yourself overcompensating on non-fasting days, which may reduce any potential effect of this approach. In fact, some people advocate non-fasting days as ‘feast’ days, suggesting you can eat what you like! This is not the case – you still need to be sensible and this approach is not a license to eat what you like you non-fasting days

If I decide to follow this approach, are there any guidelines I should follow?

As ‘one size doesn’t fit all’, it would be best to monitor and adjust your calorie intake on fasting days depending on weight. A good starting place would be aiming for an average calorie intake across the week based on an estimated requirement of 2000kcal/day for women and 2500kcal/day for men (men need more calories than women). This can then be increased or decreased depending on whether weight is staying stable or not. There are several factors affecting the ideal calorie intake, such as current weight and activity levels. Remember that when monitoring your weight, never use daily weight as an indicator, as this will only be measuring hydration and hormonal fluctuations. Using weekly or fortnightly weights is a much better way of keeping tabs on your weight. If you want to visualise what your dinner plate should look like, it should consist of half a plate of vegetables or salad, and a quarter each of wholegrain starchy carbohydrates and protein foods, e.g. meat, fish or egg.

Here are some practical guidelines that may help you choose your specific strategy if you choose a 5:2 approach:

  • It would be best to carry out exercise (especially intense or aerobic exercise) on non-fasting days. This will help ensure you are properly fuelled before and after exercise, minimising fatigue and injury
  • Eat at least 600kcal on fasting days. Tailor your other days to achieve your overall weekly allowance (using the guidance and methods explained above)
  • Whilst the research into intermittent fasting as a method of weight loss advocated two consecutive days, when it comes to weight maintenance, we suggest that you could choose any two days which fit in with your lifestyle
  • If you want an easy option, consider buying some Slim & Save packs to have on your fasting days. We offer a product which enables you to buy a month’s supply of packs (8 day’s worth if you were following a Slim & Save weight loss programme). Each S&S pack contains between 140 and 170 kcal, so you would simply need to consume four packs on a fasting day. Here is a link to this plan on our website:5:2 Intermittent Fasting Plan

Are you maintaining? Have you struggled to maintain? Please share your experiences to help others whilst at goal weight and maintaining. The best comment will be awarded a Slim & Save Snack Pack. The winner will chosen at 4pm on Wednesday 13th April 2022

Written by Annemarie Aburrow RD BSc (Hons) PGDip, Slim & Save Dietitian.


  1. Thank you for writing this great Blog. I have heard lots of people talk about and recommend intermittent fasting but I wasn’t really sure what it involved. When I get to goal this is something I will consider to help me when it comes to maintenance. So I will be sure to pop back and refresh my memory when I get the last couple of stone off 🙂

  2. I have found that 5.2 is easy for me as I know on my fast days that I just need to have a Lifestyle day as I find that I am less prone to headaches and feeling yukky and tired by having protein and veg. On my non fast days I can eat what I like but with care, as I don`t want to fill up on starchy carbs and sugar and I do still make sure that I still drink water.

  3. I have been doing intermittent fasting for a few months now that I have reached my target weight and have incorporated some exercises too and found that I have managed to keep my weight off as I find it suits my lifestyle as I`m not on a “diet” but maintaining it, if I do start to slip and the pounds start to creep back on I then do every other day intermittent fasting.

  4. This blog has come at a great time for me as I have now lost 5 ½ stone and have 3 to go. I have been contemplating how best to maintain.

    My plan was to have a tolerance of 7lbs that will tell me when to restart Simplicity because I’ve let it get out of hand again, but “normally” I would be following a fresh food cooked from scratch way of eating (such as SW which could keep me accountable with peer support) That would have been too slow a way for me to lose my weight as I had had enough of trying and not seeing results. I have been on plan for almost 4 months now, and have 3 months to go (I hope!).
    I think after reading this I may have 2 days of packs per week to stay in control.

    I’m nervous/excited to find out how many calories I need to maintain as I suspect it’s lower than expected due to ruining my metabolism by years of yo-yo dieting.

  5. This has been posted at exactly the right time for me. I lost 6 stone in 2020 and found 5 of them in 2121 and I’ve just started Lifestyle again to try and sort it out. Going into it with a clear plan for maintaining the weight loss is very motivating, I was wondering what the point of trying was when I was just going to put it all back on AGAIN! So thank you for a clear and well-written guide to a huge subject and for providing me with somewhere to start in a few months time when I’ve reached my goal. 😊

  6. As someone in a wheelchair with permanent limited mobility, this diet has become a way of life that will be followed for the foreseeable future. Keeping my weight down helps keep my joint pain, I’m less likely to fall and I feel better. I started on Simplicity, then Lifestyle, then 5:2. After 2 years with S&S, I’ve found that if I eat low carb meals during the day – no snacks – I can maintain and even continue to lose weight, while still eating foods I enjoy. I love the S&S porridge for breakfast and have S&S soup for lunch. I have a small off-plan meal with family in the evening including an occasional pudding and never feel deprived anymore. I also make sure I don’t eat between 8pm-8am. If my weight goes up, I have a few days back on Simplicity again. Life happens and S&S has taught me that quality of food is more important that quality. I started out as very obese and I’m almost into the normal weight category now so will continue to use S&S as a life plan, not just as a diet plan

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