Whether you have stumbled across the term on social media, heard it from a friend, or seen it mentioned in a health study, intermittent fasting has become one of the most talked-about approaches to healthy eating in recent years. But beyond the buzz, what does the science actually say? And how does it fit into a plant-based lifestyle?
In this article, we break down everything you need to know about intermittent fasting. What it is, how it works, the key health benefits, and practical steps to help you get started safely and confidently.
1. What Is Intermittent Fasting?
Intermittent fasting (IF) is not a diet in the traditional sense. It does not tell you what to eat but it tells you when to eat. At its core, intermittent fasting is an eating pattern that alternates between defined periods of eating and periods of fasting.
This might sound new, but humans have been fasting for most of our evolutionary history. Might be out of necessity between hunts, for religious observance, or simply because food was not always available. Our bodies are, in many ways, designed for it.
How intermittent fasting works biologically
When you eat, your body breaks down carbohydrates into glucose and uses it as its primary fuel source. Any glucose it does not immediately need is stored as glycogen in the liver and muscles, and any excess beyond that is converted into fat. When you fast, glycogen stores are gradually depleted and your body begins to tap into fat reserves for energy instead. This is the metabolic shift that underlies many of the benefits associated with fasting.
Fasting also triggers a process called autophagy (see another blog on that topic here). This is a kind of cellular housekeeping where the body identifies and breaks down damaged or dysfunctional cells and recycles their components. This process is believed to play an important role in reducing inflammation, slowing cellular ageing, and protecting against certain chronic diseases. Dr. Yoshinori Ohsumi was awarded the Nobel Prize in 2016 for his discoveries on exactly this mechanism (1).
Intermittent fasting vs. calorie restriction
One of the most common questions is whether intermittent fasting is simply another form of calorie restriction. While it is true that many people naturally eat fewer calories during fasting periods, research suggests the benefits go beyond calorie intake alone. A 2022 study published in the New England Journal of Medicine found that time-restricted eating produced weight loss comparable to conventional calorie restriction ant that without requiring participants to count calories (2). For many people, following a defined eating window is simply more sustainable than tracking every meal, which may explain why intermittent fasting leads to better long-term adherence than traditional dieting approaches.
2. Methods of Intermittent Fasting
There is no single intermittent fasting schedule that works for everyone. The most popular methods offer different structures depending on your lifestyle, health goals, and how your body responds to going without food.
The 16:8 method, the most popular starting point
The 16:8 method is by far the most widely practised form of intermittent fasting. You fast for 16 hours and eat within an 8-hour window. So for example, between noon and 8pm, or between 9am and 5pm. The overnight fast means that a large portion of the fasting period happens while you sleep, making it far more manageable than it might initially sound.
Research consistently supports the 16:8 approach (3).
The 5:2 diet
With the 5:2 approach, you eat normally for five days of the week and significantly restrict calories (typically to around 500–600 kcal) on two non-consecutive days. This method tends to appeal to people who prefer not to change their daily eating routine but can tolerate occasional low-calorie days. It is worth noting that the "normal eating" days still benefit from balanced, nutrient-dense choices.
Other variations
20:4 (the Warrior Diet): A more intensive method with a 4-hour eating window, typically in the evening.
OMAD (One Meal a Day): A single daily meal within a very compressed window. Not recommended for beginners and requires careful nutritional planning.
Alternate Day Fasting: Alternating between regular eating days and full or modified fasting days. This approach has strong research backing for weight loss but is more demanding to maintain long-term.
Which method is right for you?
For most beginners, the 16:8 intermittent fasting schedule offers the best balance between scientific evidence and practical sustainability. Start with a 12-hour fast by avoiding late-night snacking. This is a gentle way to start before extending to 14 or 16 hours. If you have any existing health conditions, are pregnant, or are on medication, always consult a healthcare professional before starting.
3. Health Benefits of Intermittent Fasting
The research on intermittent fasting has grown substantially over the past decade. Here is what the evidence currently supports.
Weight loss and fat burning
Multiple systematic reviews confirm that intermittent fasting is an effective tool for weight loss, though not necessarily superior to continuous calorie restriction in terms of total weight lost, but comparable in outcomes while being easier for many people to maintain. Crucially, studies show that fasting tends to preserve lean muscle mass better than sustained calorie restriction, meaning a greater proportion of weight lost comes from fat rather than muscle.
A 2025 clinical trial published in Annals of Internal Medicine found that participants following a 4:3 intermittent fasting plan (fasting on three non-consecutive days per week) lost 52% more weight over 12 months compared to those following a conventional calorie-restricted diet, with additional improvements in blood pressure and cholesterol levels (4).
Metabolic health and insulin sensitivity
One of the most well-established benefits of intermittent fasting is its positive impact on insulin sensitivity. During a fast, insulin levels drop significantly, allowing stored fat to become accessible for energy. Over time, this can help reduce insulin resistance — a key driver of type 2 diabetes and metabolic syndrome. Research shows that even short-term intermittent fasting protocols can lower fasting blood glucose levels and improve markers of metabolic health.
Cellular renewal and autophagy
As mentioned above, fasting activates autophagy — the body's cellular cleaning and recycling process. This is one of the most exciting frontiers in longevity science and by far our favourite here at Eat by Alex. Studies suggest that regular fasting-induced autophagy may reduce the accumulation of damaged proteins and cellular components associated with neurodegenerative diseases, support immune function, and contribute to a longer, healthier lifespan.
This is also one of the key mechanisms behind the reSET 5-day Fasting Mimicking Program — a science-based approach developed to trigger the same cellular renewal benefits as fasting, while still providing your body with carefully calibrated nutrition.
Brain health and cognitive function
Contrary to the assumption that going without food leads to brain fog, many people and our customers report sharper mental clarity during fasting windows. Animal and human studies (5) have long suggested that fasting promotes the production of brain-derived neurotrophic factor (BDNF), a protein that supports the growth and maintenance of neurons. A 2025 review published in Ageing Research Reviews (6) found no impairment in cognitive function among participants following a 16:8 intermittent fasting schedule and concluded that fasting neither harms nor diminishes mental performance in healthy adults.
Longevity and healthy ageing
The link between fasting and longevity is perhaps the most intriguing aspect of all. Research by Dr. Valter Longo (whose work also underpins the fasting mimicking diet) has demonstrated that periodic fasting can reduce markers of biological ageing and lower the risk of age-related diseases including cardiovascular disease, diabetes, and certain cancers. A 2017 randomised trial in Science Translational Medicine (7) found that three cycles of a fasting mimicking diet reduced insulin resistance, cardiovascular risk factors, and biological age markers, while a 2024 study in Nature Communications (8) reported a reduction in median biological age of 2.5 years independent of weight loss. Populations living in Blue Zones, the world's longevity hotspots, tend to naturally practise some form of time-restricted eating or periodic calorie restriction.
For a deeper dive into how diet and longevity are linked, read our article on the longevity diet and its role in reducing chronic disease risk.
4. Intermittent Fasting and Plant-Based Eating
Intermittent fasting and a plant-based diet are a particularly powerful combination and one that sits at the heart of what we do at Eat by Alex.
Why the combination works
A whole food, plant-based diet is naturally rich in fibre, antioxidants, and anti-inflammatory compounds. These properties complement the metabolic and cellular benefits of fasting beautifully. When you break your fast with a nutrient-dense, plant-based meal, your body receives the building blocks it needs to repair and regenerate — rather than a spike of processed food that could reverse some of the benefits you have just worked to achieve.
Studies also suggest that plant-based eaters may experience less hunger during fasting windows, thanks to the sustained satiety provided by fibre-rich whole foods eaten during eating periods.
For more on the advantages of a plant-based diet, read our guide to the 6 possible benefits of a plant-based diet.
Intermittent fasting vs. fasting mimicking diet. What is the difference?
While both approaches harness the power of the fasting state, they work differently. Intermittent fasting is a daily or weekly eating pattern, typically maintained long-term. The fasting mimicking diet (FMD), pioneered by Dr. Valter Longo, is a periodic 5-day protocol that provides precisely calibrated, low-calorie, plant-based nutrition designed to keep the body in a fasting-like metabolic state while still supplying essential nutrients.
The key distinction is depth: the fasting mimicking diet is designed to more profoundly activate autophagy and cellular regeneration, making it a powerful complement to rather than a replacement for regular intermittent fasting. Think of it as a periodic reset that takes your fasting practice to the next level.
This is exactly what reSET by Eat by Alex] is designed to do. Developed in line with the science of fasting-mimicking, the nutritionist-approved reSET program is a 5-day plant-based fasting mimicking program that supports fat burning, cellular renewal, and metabolic health and that all from the convenience of your home in Switzerland & Lichtenstein.
Practical tips for plant-based intermittent fasting
- Break your fast with protein and fibre first. A meal of legumes, leafy greens, and healthy fats stabilises blood sugar and reduces the likelihood of overeating in the hours that follow. Here our 7 favourite recipes high in proteins
- Stay hydrated during fasting windows. Water, herbal teas, and black coffee are all compatible with a fast and help manage hunger.
- Plan your eating window around your lifestyle. If you train in the morning, consider a slightly earlier eating window to support recovery.
- Avoid ultra-processed foods during your eating window. Fasting's benefits can be undermined if the foods you eat during eating periods are high in refined sugar, saturated fat, and additives.
For ideas on how to make plant-based eating easy and enjoyable, visit our blog: Let's make eating plants easy.
5. How to Get Started with Intermittent Fasting
Starting any new health practice takes a little planning. Here is a simple, realistic approach.
Step-by-step guide for beginners
Week 1 | Start with 12 hours. Simply stop eating after dinner and delay breakfast until 12 hours later. If you finish dinner at 8pm, have breakfast at 8am. This is often all it takes to begin noticing a difference in energy and appetite regulation.
Week 2–3 | Extend to 14 hours. Push your first meal to 10am. This is a comfortable midpoint that most people adapt to easily.
Week 4 onward | Try 16:8. Your first meal at noon, your last meal by 8pm. This is the sweet spot that most research supports and most people find sustainable.
A sample intermittent fasting meal plan (16:8)
12:00 — Break your fast
A large salad with our famous & nourishing beetroot and blueberry bowl.
15:30 | Afternoon snack
A small handful of mixed nuts and a piece of seasonal fruit or two boosting matcha power balls.
19:30 | Evening meal
A lentil and vegetable stew with brown rice and a side of fermented vegetables or a homemade Red Thai Pumpkin Curry.
During the fasting window (8pm–12pm)
Water, lemon water, herbal tea, black coffee — all permitted.
Common mistakes to avoid
- Breaking the fast with a large, sugary meal. This spikes insulin and can undo metabolic benefits. Start gently with balanced, whole foods.
- Under-eating during the eating window. Intermittent fasting is not about starving yourself. Meeting your nutritional needs within the window is essential.
- Giving up after a difficult first week. The first few days can bring headaches and hunger as your body adapts. This is normal and typically subsides by day 4–7.
- Ignoring your body's signals. If you feel unwell, dizzy, or excessively fatigued, shorten your fasting window or consult a professional.
When to consult a healthcare professional
Intermittent fasting is not suitable for everyone. You should speak with your doctor before starting if you are pregnant or breastfeeding, have a history of disordered eating, have type 1 diabetes or are on insulin or blood sugar medication, are underweight, or are under 18 years of age. Women may also experience different responses to fasting than men, particularly in relation to hormonal balance, and may find shorter fasting windows (12–14 hours) more appropriate, especially in the early stages.
Intermittent fasting is one of the most well-researched and accessible tools for improving metabolic health, supporting healthy weight management, and activating the body's own cellular renewal processes. When paired with a whole food, plant-based diet and complemented by periodic deeper resets its benefits extend well beyond the short term.
You do not need a complicated plan or expensive supplements to get started. Begin with a 12-hour window, listen to your body, and build from there.
If you are ready to take your fasting practice further, explore the reSET 5-day Fasting Mimicking Program our science-backed, plant-based protocol designed to support deep cellular renewal, delivered to your door anywhere in Switzerland.
Podcast on what does science say about intermittent fasting by the ZOE team
Frequently Asked Questions
What can I eat during intermittent fasting?
During your fasting window, you should stick to zero-calorie drinks (avoid light drinks): water, herbal tea, black coffee, and lemon or cucumber water. During your eating window, focus on whole, nutrient-dense foods and ideally plant-based.
What breaks a fast?
Any food or drink containing calories technically breaks a fast. Black coffee and plain tea are generally considered acceptable as they have negligible caloric content and do not appear to significantly impair the metabolic benefits of fasting.
How long does it take to see results from intermittent fasting?
Most people notice changes in energy and appetite regulation within 1–2 weeks. Measurable changes in body composition and metabolic markers typically appear after 4–8 weeks of consistent practice.
Is intermittent fasting safe for women?
Generally yes, but women may be more sensitive to extended fasting periods. Starting with a 12–14 hour window and monitoring how you feel is particularly important. Some research suggests women benefit from a slightly gentler approach, particularly around the luteal phase of the menstrual cycle.
What is the difference between intermittent fasting and the fasting mimicking diet?
Intermittent fasting is a daily eating pattern. The fasting mimicking diet is a periodic 5-day protocol designed to more deeply activate cellular regeneration and autophagy while still providing essential nutrition. The two approaches complement each other and reSET is our plant-based fasting mimicking program to support exactly this.
Sources
(1) https://www.nobelprize.org/prizes/medicine/2016/press-release/
(2) https://www.nejm.org/doi/full/10.1056/NEJMoa2114833 & https://www.nejm.org/doi/full/10.1056/NEJMe2202821
(3) https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(22)00332-9 & https://www.nature.com/articles/s41430-023-01311-w)
(4) https://www.acpjournals.org/doi/10.7326/ANNALS-24-01631
(5) https://www.frontiersin.org/journals/aging/articles/10.3389/fragi.2023.1161814/full
(6) https://pmc.ncbi.nlm.nih.gov/articles/PMC12180010/
(7) https://pubmed.ncbi.nlm.nih.gov/28202779/
(8) https://www.nature.com/articles/s41467-024-45260-9