This five day fast landed on my doorstep in perfect time for my imminent holiday to Mallorca and although I wasn’t particularly desperate to lose any kilos, I had just had a facial, and thought a bit of pre-vacay self care would not go amiss, so I was quite excited to receive my box of goodies. And it was a pretty large box for something that mimicked a ‘fast’!
To be clear, this isn’t actually fasting in the traditional, grumbling-stomach, spiritual-enlightenment-through-suffering sense. This is Fasting™ the ProLon way – packaged, portioned and promising to rejuvenate your cells, trim your waist and reverse your biological age (or at least make your skin look glowy on Instagram).
The programme – a brainchild of renowned longevity researcher Dr. Valter Longo, mimics fasting by tricking your body into – technical speak, ketosis and autophagy—all while still feeding you soup, snack bars and vaguely medicinal glycerin water. And, you’ll come across plenty of other marketing buzzwords such as “bioaging score,” “cellular clean-up” and “fasting without fasting” within the blurb in the box of this celebrity-backed product.
Broken down into science, ProLon is built on legit research: by restricting calories (1,100 on day one and ~700-800 for the rest), your body supposedly enters a fasted state without fully abstaining from food. The goal is cellular rejuvenation via autophagy, improved metabolic health, and potentially reducing markers of aging. It’s nutritionally engineered fasting with plant-based meals, multivitamins, and a thing called an “L-drink” that supports lean muscle mass and can be consumed in a grown ups beaker with a straw!
Ideally start mid week, or at least plan your fast for when you don’t have any prior social engagements to ensure the smoothest ride- and when you’re imbibing the least calories on days 4 and 5, you can just binge on Netflix in your PJs without any external temptations from the real world!
My experience
Day 1 was smooth sailing—basically a light meal prep day with pretty packaging. By Day 2, I realised the nut bars were the highlight of the program (and I’m 90% sure they contain unicorn dust because they’re actually delicious). Days 2 and 3 were a bit rough—brain fog and boredom. But by Day 4, a strange clarity kicked in. Whether it was ketosis or the sheer pride of not raiding my treats cupboard (although I did dream about Scampi Fries!!) I started to feel more focused – possibly knowing I just had one day to go, and I was plotting my first solid meal. Day 5 felt almost normal – I wasn’t hungry but I wasn’t full, I was functional. I got through meetings without daydreaming about sourdough and even finished off with a nightcap – not strictly on the plan, but well deserved I think.
The Pros
-Genuinely well-organized: five individual boxes, clearly labeled, zero guesswork.
-You don’t feel totally deprived: there’s food! There’s even (surprisingly tasty) snack bars
-Backed by solid science: Unlike many fad cleanses, ProLon has clinical studies and real researchers involved.
-Convenient: No planning, no cooking, no mental effort.
The Cons
-It’s expensive—you’re paying for research, packaging, and peace of mind.
-It’s still a diet: Call it fasting-mimicking, call it cellular optimization—at the end of the day, you’re consuming under 800 calories. Expect to feel it.
-You WILL feel hangry at some point! Despite the claims of sustained energy, I wouldn’t schedule high-stakes presentations on Days 2 or 3.
The Verdict
If you love the idea of optimizing your mitochondria while sipping herbal tea and Instagramming your kale crackers, ProLon is a strong contender. If, however, you think health shouldn’t come in five identically packaged cardboard boxes—or you’d rather just intermittently skip breakfast and save the money, this may not be your thing.
But hey, I lost a bit of weight, my skin looked great, and I didn’t collapse from hunger. That’s worth something, right?
Shop yours here