Fasting Without Starving? My Experience with the Fasting Mimicking Diet
- Gemma Westfold
- Jul 9
- 5 min read
Updated: Sep 26
What if you could get the benefits of fasting without giving up food completely?
That is the idea behind the Fasting Mimicking Diet (FMD), developed by Professor Valter Longo (see picture below of me with him at a conference last month) . It is a 5-day structured programme designed to nourish your body while triggering some of the powerful cellular benefits of fasting, such as improved blood sugar control, visceral fat reduction, and autophagy (your body’s natural cellular clean-up process).
With over 100 clinical, peer reviewed trials exploring the benefits in cancer, metabolic disease, autoimmune and healthy ageing (longevity), this is the one to watch.
Why consider fasting?
Fasting has been used for centuries for health, spiritual, and metabolic benefits. Research shows that fasting, when appropriate and done safely, can:
✔ Improve insulin sensitivity and blood sugar control
✔ Reduce inflammation
✔ Activate autophagy, helping your body clear out damaged cells and support cellular rejuvenation
✔ Slow ageing
✔ Promote fat loss while preserving lean muscle mass
However, traditional water-only fasting is not suitable for everyone and can be hard to sustain, especially alongside work, parenting, or training.
What is autophagy, and why does it matter?
Autophagy literally means “self-eating”. It is your body’s natural housekeeping process where it breaks down and recycles damaged cells and cellular components that are not working effectively. Think of it like restructuring your cells and tissues so that your body runs more streamlined, efficiently, and with stronger, healthier cells.
Autophagy:
✔ Clears out dysfunctional proteins and damaged cell parts that can lead to disease
✔ Supports immune function by helping remove infected or malfunctioning cells
✔ Encourages stem cell regeneration, which supports tissue repair and rejuvenation
✔ Helps the liver by reducing fat accumulation and improving its detoxification capacity
Fasting is one of the most effective ways to trigger autophagy. The FMD achieves this while still providing nourishment, so you get the cellular benefits without full starvation stress.
So what is FMD exactly?
FMD is:
✔ A structured, low-calorie, plant-based meal plan (soups, bars, herbal teas) designed to keep you in a fasting state while still eating
✔ Low in calories and protein to mimic fasting physiology
✔ Designed to provide essential micronutrients, reducing the risks of nutrient depletion seen in prolonged fasting
The Fasting Mimicking Diet (FMD) keeps calories and protein very low for five days – this isn’t a full-time way of eating (I normally eat plenty, and I keep my protein intake high). By temporarily reducing calories and protein, the FMD blunts growth signals such as mTOR, AMPK, and IGF-1, which in turn triggers deep cellular clean-up processes like autophagy.
The nutrition in the FMD is specifically formulated to stay below the thresholds that activate these nutrient-sensing pathways. This means that although you’re still getting some nourishment, your body perceives it as fasting. It’s fasting with nourishment, not fasting through starvation. For me, the evidence behind this approach was overwhelming, and my health needed the reset that only this level of cellular clean-up could provide.
Why I tried FMD
Earlier this year, I discovered I had mould toxicity after an exposure that left me very exhausted. After finding the culprit (thank you functional medicine) and feeling back to normal, I wanted to support my immune system further and help my liver function and detoxification pathways.
The FMD may support detoxification by reducing the load of digestion for a few days, allowing the liver and gut to focus on clearance, while autophagy helps clear out damaged cells, cellular debris, and immune-senescent cells that can drive inflammation or immune dysregulation.
I found FMD challenging at times because I am a real eater and love to eat, but I stuck with it and felt very energised by the end. My focus improved, my mood lifted. Importantly, I have not lost muscle mass. One of the key benefits of FMD compared to water fasting is that it helps protect against muscle breakdown. The low protein, low calorie but micronutrient-rich formulation provides enough nourishment to maintain lean tissue while still activating fasting physiology.
Who is it for?
Research suggests FMD may be beneficial for people who:
✔ Want to improve metabolic health or reverse insulin resistance, diabetes and fatty liver
✔ Seek visceral fat loss while maintaining muscle
✔ Are interested in longevity, cellular health, and immune resilience
✔ Find total fasting too difficult or contraindicated (i.e. all of us)
Who might need caution with FMD or fasting in general?
Those with nutritional deficiencies, such as low iron, B12, or vitamin D, as it is essential to optimise nutrient status first to avoid depletion. For example, vitamin D sufficiency improves fasting outcomes, while deficiency may worsen fatigue and immune resilience.
People with a history of eating disorders, as fasting can be triggering.
Individuals with Hashimoto’s or other autoimmune thyroid conditions. Fasting may exacerbate stress on the thyroid and adrenal axis, although for some autoimmune conditions such as rheumatoid arthritis or MS, supervised fasting shows potential benefits.
Those who are pregnant, breastfeeding, or underweight.
What about perimenopausal women?
This is an important nuance. Perimenopause is a hormonally sensitive time. Daily intermittent fasting (such as 16:8) may not suit everyone and can worsen symptoms such as sleep issues, anxiety, or fatigue if cortisol is already dysregulated.
However, short-term fasting mimicking diets of just five days, done a few times a year, may be beneficial for metabolic health, weight management, and longevity without causing hormonal disruption, provided nutrition, sleep, and stress are supported before and after. Every woman is different, and personalisation is key. This is where I come in.
Different fasting approaches
Time-restricted eating (TRE): Eating within an 8 to 12 hour window daily. Supports circadian rhythm and digestion. Not for everyone and I don't recommend during certain times in the menstrual cycle and perimenopause.
5:2 Diet: Eating normally five days a week and reducing calories significantly on two non-consecutive days. Can support weight management but may not suit women with hormonal imbalances or thyroid issues.
Fasting Mimicking Diet (FMD): Mimics fasting for cellular benefits while still eating. Typically done for five days, a few times a year.
OMAD (One Meal A Day): Eating only one meal in 24 hours. I do not recommend this approach for women as it can disrupt hormones, thyroid, and cortisol balance. I am not keen on it for men either due to its potential impact on muscle preservation, testosterone, and stress hormones.
Water-only fasting: Needs close supervision and is not suitable for most people without medical guidance.
Final thoughts
Fasting is not about punishment or willpower. When approached safely, it can be a powerful tool for health optimisation. But it is not a one-size-fits-all strategy. If you are curious about fasting, fasting mimicking diets, or time-restricted eating, it is important to:
✔ Assess your current nutritional status
✔ Consider your hormone health, stress levels, and thyroid function
✔ Personalise fasting to your goals and health needs
If you would like to explore whether fasting or FMD could fit into your health strategy safely and effectively, then book in a free Health Review. I would not recommend it without knowing nutrient status, and certainly not without professional, personalised advice - so consider looking at my Wellness Check and discuss my new package of the Wellness Check, five day FMD diet and personal support.
Book a free 20-minute ‘Health Review’ call today, and let’s discuss your health in detail.
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