What happened when I tried the ProLon Fasting Mimicking Diet

Anyone that follow trends in the health and wellness industry will know that fasting diets are a big deal right now.

The Fasting Mimicking Diet (FMD) has gained widespread attention due to its purported health benefits, including weight loss, improved metabolic health and cellular rejuvenation. But is it all its cracked up to be? I wanted to find out for myself.

Image Credit: Prolon website

I first heard about FMD on the Goop Lab Netflix documentary series.  According to its creator, Dr Valter Longo, the diet is designed to enhance cellular rejuvenation and support longevity. The fast does this by tricking the body into thinking its in a full fasted state , while still allowing you to eat real food.

The thought of skipping food for long periods or living off juices, water or one particular food has always put me off fasting.  What I like about FMD is that its short term and there are no restrictions on when you can eat each day. That said, I still felt a little daunted.

What is a Fast?

There are many different types of fasts, however, they all involve some form of calorie restriction. As part of my nutrition training, I reviewed the evidence for and against many of them. Overall, I found there to be a lack of consensus. With so many variations, it is difficult to make generalized claims about health benefits. Many fasts also carry significant risks which is why I have never recommended them to my patients. The restrictive nature of fasts worry me, especially for those that are susceptible to disordered eating.  However, in the spirit of research, and because i’ve been overindulging in caffeine and alcohol during lock down,  I felt that now was a good time to get some first-hand knowledge on the subject.

What is the Fasting Mimicking Diet (FMD)?

In a nutshell, FMD is a high-fat, low-calorie intermittent fasting method. Here is what it entails:

-        You are supplied with a box that contains prepackaged meals for five days. Total kcals range from approx 1,150 kcals on day 1 to 800 kcals for days 2-5. You get a menu card which tells you what to eat on each day

-        You eat and drink only what is supplied in the boxes for that day but you can change the order of when you eat the food

-        You must limit strenuous exercise

-        You can have unlimited plain water, black decaf tea and coffee and herbal tea

-        The company recommends doing the fast every month for 3 consecutive months. After completing the first three cycles, you can do the fast from time to time to enhance cellular rejuvenation

-        The fast is not recommended for anyone with a chronic health condition, pregnant, breastfeeding or has a history of an eating disorder

How does it work?

The gradual calorie restriction is designed to trick the body into thinking it is in a full fast. This triggers a stress resistant mode, enhancing cell autophagy. In other words, your body’s cellular clean -up crew get to work removing damaged cells. For a visual of what happens day to day refer to Fig 1 above

My Experience

The first big challenge I had was trying to find a 5 day stretch when I wouldn’t have any events or social outings around food. Thankfully, being in lock down helped with this, but I still had to endure a couple of restaurant trips with family which was tough. Also, as a mom to an energetic one year old, there were times when I felt that I needed a caffeine/ calorie boost to get me through the day. To try and make things easier, I limited strenuous exercise and cancelled any big plans.

Day 1

I was excited to open my first food box and find out what I had lined up!

Meals on the first day are around 1,050 kcals total. Spread out across the day this actually didn’t feel too bad.  The food is conveniently grouped by day and you are provided with a breakdown of breakfast, lunch, dinner and snacks making it very easy to follow. For breakfast I had a chunky nut bar – this was by far and away my favorite food item. Thankfully you get one of these each morning. Lunch and dinners are less exciting – an assortment of different plant-based soups. The snacks vary by day but are either olives, kale crackers or coco crisp bars, or a combination.

I didn’t feel that hungry during the first half of the day, but come evening, I got a gnawing feeling in my stomach. To distract myself, I drank a large glass of water, two cups of mint tea and kept myself busy around the house.   

Day 2

By morning, the hunger I felt from the night before had gone but I did have a headache. I’m not sure if this is simply caffeine withdrawal (I usually drink around 2-3 cups of tea and coffee a day), or a normal side effect of calorie restriction.

Starting on the second day, the kcals drop down to around 800 kcals. This is approximate because on the second day you start adding a fruit flavored syrup, known as the L Drink to water. The amount of syrup you add depends on your body weight. According to the diet’s developers, the purpose of the L drink is to stop your body from breaking down amino acids and losing muscle mass.

By the second day, the reality set in that the small quantity of food in the box had to last me all day! I’ll admit, this did feel a little scary. I found myself trying to keep busy to stop myself going into the kitchen or thinking about food. The evening stomach growling from the first day returned and persisted into the evening.

Day 3  

I found the third day the hardest by far. Thankfully, my headache had gone, but I felt bloated. I have a history of IBS, so I wasn’t overly surprised, but it was uncomfortable. Another cause could be the inulin content of the breakfast nut bar. Inulin is a prebiotic fiber extracted from chicory root. While it is considered a healthy fiber, inulin is also known to cause abdominal bloating in susceptible people.

By the afternoon, all I could think about was food! I was continually having to keep hunger at bay. I delayed eating the nut bar until the late morning and spread out my snacks.  The soups aren’t terrible, but some flavors (namely the white bean/ spinach and vegetable) are bland. The lack of variety for lunch and dinner was one of the hardest aspects of the fast.   

Day 4  

Today marked a turning point. The bloating disappeared and I generally felt a lot lighter in my body. My hunger signals also seemed less intense and I didn’t feel a strong urgency to eat. If anything, I felt that I was much more in tune with my hunger and satiety cues. Instead of continually grazing throughout the day, I was better able to identify genuine hunger.

Day 5

By the last day, I felt that my body had adjusted to the reduced intake. My mind also felt a lot clearer and I felt calmer than I have in a long time. While I was looking forward to resuming normal food, I didn’t feel as preoccupied with food as before but I did feel quite tired by this point.

Day 6 (Transition Day)

The day after the fast is known as the ‘transition day.’

They recommend that you ease back slowly into normal eating by having soft foods and liquids. I had a Harvest Bowl green and ginger smoothie with added rolled oats for breakfast. Throughout the day I ate small amounts of soft food and plenty of water. The tiredness I experienced the day before was still there but I also had a strong sense of tranquility and felt much calmer.

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What’s The Verdict?

On balance, my experience with FMD was positive. The fast is easy to follow thanks to the prepacked boxes, and while there were times when I was very hungry, it was manageable (helped by drinking a ton of water and tea throughout the day!). I was also surprised to find that my energy levels were fairly good, aside from the last two days.

With all that said, I don’t think this fast is for everyone. I did experience some headaches, bloating and tiredness. If you have a particularly active lifestyle, I think it would be tough to stick to due to the calorie restriction. As already mentioned, pregnant and breastfeeding women and those with prior health conditions are not advised to try it.

The positives:

• The calorie restriction strengthened by hunger and satiety cues. By the last day, I was more aware of when I was genuinely hungry versus just bored or thirsty

• It encouraged me to up my fluid intake considerably

• By the last day I felt calmer and my concentration and focus were heightened. This effect can partially by explained by the fact that your body is entering a state of ketosis after a few days of increasing fat and restricting carbs

• I felt lighter in my body

The negatives:

• The food lacks variety

• Fiber and omega 3 fatty acids intake is low. The low fiber could be an issue if you are prone to constipation

• There are some side effects, including fatigue, headaches, bloating - these are only what I experienced

• The cost. At a retail price of $250 per box, this is far more expensive then many other fasts out there. While the convenience of the prepacked boxes is great, based on the high price tag, it’s debatable whether this fast is better than other cheaper intermittent fasts out there.

Have you tried FMD? I would love to hear about your experience – please share your comments below.

Interested in trying Prolon? I offer complimentary 15 minute discovery calls, once we establish if Prolon is a good fit for you I can offer exclusive discounts on the program. Shoot me an email to schedule your call today, tamsin@jordan-nutrition.com