Book phone

ProLon® is a revolutionary nutritional programme, devised by Dr Valter Longo, biogerontologist and author of the bestselling Longevity Diet. The first of its kind, this fast-mimicking 5-day dietary plan was developed following an extensive scientific research programme in the USA to create a natural, plant-based diet which is clinically tested and offers the health benefits of fasting. ProLon® nourishes your body whilst supporting its overall health, having a positive impact on a number of health-related issues, from increasing relative lean body mass to decreasing raised cholesterol, inflammation and fasting glucose levels.


The perfect complement to our range of aesthetic and wellbeing treatments, ProLon® is clinically proven to induce a fasting state which optimises metabolic health and decreases age-related risk factors. This rejuvenation effect is the main reason why ProLon® followers lose fat very quickly while preserving lean body mass (muscle and bone) and, ultimately, extend their ‘healthspan’.

Benefits of Prolon®


Improved sleep

Improved cognitive function

Reduced inflammation

Weight loss

Conditions Treated

General skin health



Menopausal/hormonal imbalance


“From the first phone call to reception through to time spent with the doctors, Waterhouse Young Clinic makes prospective patients feel well looked after and comfortable as they consider potential ...

JE, Lawyer


“Who knew that a neck treatment could be so relaxing and I never imagined my skin would ever feel this smooth from the wonderful Allskin Med products. I was sceptical ...

Gaby Roslin


“I’ve trusted the doctors at Waterhouse Young clinic for 10 years and – if I say so myself – I’m pretty pleased with the quality of my skin and how ...

Alice B-B, Spa Editor, Times LUXX


When my skin feels tired Waterhouse Young HydraFacials are my go-to – my skin feels fresh, hydrated, and firmer. I love them especially before an event for an extra glow.

Suki Waterhouse, Model & Actress


I visited Waterhouse Young for my pre-wedding skin prep and wasn’t disappointed! My skin has never been in better condition, and it was literally glowing on the day thanks to ...

Gabriella Maubec


Love visiting this clinic! Leanne and Dr Paris are so friendly and welcoming you feel like no time has passed since the last visit. All my treatments look so natural ...

Alexandra Simpson


Everyone is so lovely and knowledgable here. My skin has never felt so good.

Dani Tucker


Highly professional and friendly staff, made me feel very welcome on my first visit. Had the hydrafacial and my skin has never felt better! Can’t recommend Waterhouse Young enough.

Natasha Patterson


So delighted with the results. WY’s lovely team recommended the Seqex bed for my inflammartory condition and, having had the issue for 5 years , have to say I was ...

Melanie Parkfield


I was recommended the clinic by a friend and have been for a series of their HydraFacial ahead of my wedding. I cannot say enough good things, the team are ...

Sarah Powell


Awesome clinic, Anna and her team are clearly really passionate about what the do, not only do they help you look great but they’re really care about your well being, ...

Alan S Adams

Prolon® Treatment Guide & FAQs

ProLon® is the first Fasting Mimicking Diet™ (FMD™): a programme developed to provide the beneficial effects of fasting but with a natural, plant-based food plan, making the fasting-mimicking period safe and pleasant. The Fasting Mimicking Diet™ (FMD™) is a high nutrition, low protein, low carbohydrate meal plan, clinically proven to beneficially change a wide range of biomarkers associated with ageing, poor health, and inflammation. The low-calorie, high-fat, low-carb content of the meals causes your body to generate energy from non-carbohydrate sources after glycogen stores are depleted – a process known as gluconeogenesis.

ProLon® contains plant-based soups, bars, crackers, olives, drinks, and supplements and is a proprietary 5-day dietary programme, providing approximately 750 to 1100 calories per day. It is based on innovative research carried out at two of the world’s leading centres for biomedical and longevity research located at the University of Southern California (USC), the Longevity Institute and the Diabetes and Obesity Research Institute. This revolutionary meal plan has been scientifically designed and clinically tested to mimic the effects of fasting, while providing the proper daily nourishment and the feeling of satisfaction.

You might like to talk to one of our aesthetic practitioners about ProLon when you’re having another treatment with us or we can book an appointment with you to talk about ProLon® specifically.

We will discuss your medical history and lifestyle and you will fill out a health self-assessment which will determine if you are suitable for ProLon®. Assuming you are, we will give you your five-day course with simple instructions to follow this nutritional programme.

An appointment with one of our aesthetic practitioners to discuss your suitability and to explain the ProLon® programme will take half an hour or so. As above, it’s also possible for us to discuss it with you when you are having another treatment with us.

ProLon® is suitable for anyone who is looking to optimise their health. ProLon® was shown in clinical trials to have beneficial effects on a wide variety of markers which impact your long-term health: it decreases abdominal fat while increasing relative lean body mass, decreases fasting glucose, reduces C-reactive protein (a marker of inflammation) and reduces IGF-1 (associated with increased DNA damage mortality and ageing in humans).

The programme should be followed for 5 consecutive days, after which you will transition for 1 day and then resume your normal diet. Easy-to-follow instructions are provided in every carton and we can advise you too.

A specific combination of food is provided on each day for breakfast, lunch, dinner and snacks. All food provided on a specific day should be taken on that day only and, while a meal missed can be made up at any time during the same day, there should be no carryover from one day to the next.

This depends on your baseline markers and health measurements, assessment and any recommendations we have made. Some people find once is enough, others follow the programme each month. For the majority of reasonably healthy people, once or three times a year is sufficient, ideally consecutive months.

You may like to try the five-day course and then check in with us afterwards to decide if and when you’d like to repeat it. If you’d like to try the programme for three months, we can also carry out a simple blood test before and after to see how your biomarkers have changed and therefore ascertain how ProLon® has helped you.

Yes, ProLon® is very safe – it is a 100% natural, plant-based programme which was developed after years of extensive scientific research in the USA with an investment of $25m. The proprietary dietary formulation is based on decades of scientific research, including preclinical and clinical trials, and contains specific, safe, natural ingredients that were put together to mimic fasting, while optimising nourishment and maximising your health.

A ProLon® box containing everything to complete a full 5-day Fasting Mimicking Diet costs £225 (excluding optional blood tests).

As seen in

Get in touch

We look forward to welcoming you to our London skin clinic in the heart of the Harley Street medical district.