How the experts do intermittent fasting (2024)

If you haven’t tried intermittent fasting yet, you could be missing out. Now more popular than a ketogenic or high-fat diet, even the Prime Minister is a fan, fasting for 36 hours every week.

It’s not just the fat-burning, weight-shedding benefits that make it so popular. Hailed for boosting our “metabolic resilience”, hardly a day goes by without a new study showing the multiple health benefits of time-restricted eating, leading to improvements in diabetes, cardiovascular disease, obesity, cancers and neurological disorders.

The latest study, by Cambridge scientists, claims that fasting for 24 hours may protect us against dementia and Parkinson’s by reducing inflammation. There are many different ways of incorporating fasting into your week: here, five health experts reveal how they make it work for them.

‘I eat three meals a day between 8 and 8’

Dr Clare Mosley, 62, GP

How the experts do intermittent fasting (1)

My husband, Dr Michael Mosley, created the 5:2 diet 12 years ago – where you eat normally on five days a week, and reduce to 800 calories on the other two. Following that, he lost 9kg in 8 weeks and reversed his type 2 diabetes, and he still regularly does an 800-calorie fast day on a Monday to prevent weight creeping back on.

I follow a daily 12:12 pattern, eating breakfast at 8am and finishing my evening meal by around 8pm, and then not eating until the following morning.

Breakfast might be kippers with tomatoes, or sometimes rolled oats porridge, or granola with nuts or seeds, to stay full until lunchtime.

For lunch we have a filling home-made soup, such as a spicy tomato and lentil soup with pita bread. For supper, we will often have oily fish, like salmon, cooked in the air fryer with a simple sauce, plenty of veg and brown rice or quinoa.

We have a big glass of water with every meal, which is vital when fasting to prevent headaches, light-headedness and constipation.

thefast800.com

‘I gave up big breakfasts and have more steady energy levels’

James Davis, 51 midlife health coach and personal trainer

How the experts do intermittent fasting (2)

I’ll start the day with a HIIT workout, and then breakfast around 8.30am is a power smoothie of frozen berries, oats, chocolate-flavoured protein powder, super green powder, linseeds, chia seeds and good-quality peanut butter.

Lunch around 1pm is two scrambled eggs with mushrooms or tuna with sweetcorn and salad, both with sourdough toast – I have my carbs early in the day.

Dessert is low-fat low-sugar Greek yogurt with protein powder, and I’ll have a couple of protein shakes throughout the day, as I work out a lot and it helps keep hunger at bay.

I follow a 10:14 eating pattern, so dinner is at 6.30pm, and I have grilled fish or meat with oven-roast veg or a stir-fry, and I allow myself one square of high-cocoa content dark chocolate.

I used to love a big breakfast early in the day so I found it hard at first, but I’m glad I persevered as intermittent fasting leaves my energy levels more constant – I don’t get carb slumps and sugar spikes any more. I’ve been doing it so long now that I find it easy to fit into my lifestyle and it helps manage my body composition.

themidlifementors.com

‘An early dinner is much better than missing breakfast’

Natalie Burrows, 34, Type 2 diabetes nutritionist

At least two days a week I just eat two meals. I follow a 7:17 pattern, with breakfast at 9am – a 5-egg omelette with kimchi and sauerkraut, feta and rocket, then lunch at 4pm, which is salmon with a green salad or marinated roasted chicken with a mixed salad, and I don’t eat again that day.

Finishing dinner earlier is much more beneficial than missing breakfast. On non-fasting days I have lunch at 1pm and dinner at 6pm, and make sure I eat lots of protein and fibre, so I feel full.

I have a genetic predisposition to Type 2 diabetes, which my grandfather had. I was insulin resistant through my teens, always exhausted, but nowadays I have more energy, feel mentally sharper and sleep like a baby.

For years my weight fluctuated, but since I started intermittent fasting, I haven’t had to get on the scales – I’m slim and happy and it’s improved my relationship with food.

integralwellness.co.uk

’24-hour fasts make me mentally sharper and more focused’

Dr Patapia Tzotzoli, 43, clinical psychologist

A few years ago, I tried intermittent fasting following a recommendation from my personal trainer. Delving into the research, I was intrigued by its potential for brain and psychological health benefits.

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Now I fast three times a week, having my last meal around 6pm and then only have a coffee and water for the next 24 hours. I’m not overly strict with this routine, sometimes breaking my fast around 1pm with something light, like nuts or soup. But on the whole, I quite enjoy 24-hour fasting as it makes me feel more in control and simplifies the decisions of when and what to eat. I even find myself less hungry than on the days when I have breakfast, lunch, and dinner. I love good food, and this makes the process of fasting a well-invested tactic for delayed gratification!

On my non-fasting days I have a coffee with a muffin for breakfast, then lunch around 12 noon of chicken, rice and salad or pork with roasted veg, then dinner’s around 6pm and I’ll have something like beef or fish with roasted or steamed veggies.

Fasting has enhanced my mental sharpness and focus, especially upon waking. I feel more alert and ready to engage with my day’s tasks. It also boosts my overall energy levels, helping me stay active and attentive throughout the day.

www.patapiatzotzoli.com

‘Fasting on intermittent days stops me eating mindlessly’

Helen Bond, 50, registered dietician

I dabble in time-restricted eating on intermittent days throughout the week and always do it on a Monday because it helps me reset after the weekend. On fasting days a morning trip to the gym leaves me needing lots of protein to feel full and balance out the hunger, so at 12pm I’ll have my first meal of the day – two eggs with avocado on sourdough bread with nuts and seeds, or a chicken dish with a baked potato.

I’ll often have snacks in the afternoon like peanut butter on oatcakes or Greek yogurt and berries to top up on nutrients, especially if I’m feeling hungry because of the exercise earlier in the day. These will get me through to my evening meal of stew with lots of pulses and whole grain rice around 5pm. That’s the last thing I eat until breakfast. I go to bed early so I don’t feel too hungry.

As well as helping me maintain a healthy weight, following this 5:19 pattern on alternate days makes me become more in tune with my hunger signals. It acts as a reset, so I don’t just eat mindlessly.

@helenbonddietitian

How the experts do intermittent fasting (2024)

FAQs

Is there any scientific evidence for intermittent fasting? ›

Studies discovered that intermittent fasting boosts working memory in animals and verbal memory in adult humans. Heart health. Intermittent fasting improved blood pressure and resting heart rates as well as other heart-related measurements.

What do doctors say about intermittent fasting? ›

Intermittent fasting is safe for many people, but it's not for everyone. Skipping meals may not be the best way to manage your weight if you're pregnant or breast-feeding. If you have kidney stones, gastroesophageal reflux, diabetes or other medical problems, talk with your doctor before starting intermittent fasting.

What is the most successful intermittent fasting? ›

Many people consider the 16/8 method the simplest and most sustainable form of IF — you might want to try this practice first. If you find it easy and feel good during the fast, then maybe try moving on to more advanced fasting methods. Another approach is to fast whenever it's convenient.

Why is 16 hours the magic number for fasting? ›

While both 12-hour and 16-hour fasting can promote fat burning, it's possible that a 16-hour fast may be more effective. This is because the longer fasting period may lead to a greater depletion of glycogen stores, which can trigger higher levels of fat burning.

What is the scientific logic behind fasting? ›

Essentially, fasting cleanses our body of toxins and forces cells into processes that are not usually stimulated when a steady stream of fuel from food is always present. When we fast, the body does not have its usual access to glucose, forcing the cells to resort to other means and materials to produce energy.

How long does it take to lose 10 pounds with intermittent fasting? ›

Weinandy says that results are usually apparent around the 10-week mark, adding that she sees an average weight loss of seven to 10 pounds over that period through any of the three approaches to intermittent fasting mentioned previously. It might take longer than that since everyone's metabolism works differently.

How long does it take to lose 20 pounds with intermittent fasting? ›

Yes, intermittent fasting may help you lose 20 pounds in 2 months. This involves cycling between periods of eating and fasting. This can be an effective approach as it allows you to reduce your overall calorie intake while eating satisfying meals (5).

What happens after 1 month of intermittent fasting? ›

Here are some of the changes that may happen in your body as a result of intermittent fasting: Insulin level: Your blood level of insulin drops significantly, which promotes fat burning. Human growth hormone (HGH) level: Your blood level of HGH may increase dramatically.

What foods won't break a fast? ›

Foods you can eat while fasting
  • Water. Plain or carbonated water contains no calories and will keep you hydrated during a fast.
  • Coffee and tea. These should mostly be consumed without added sugar, milk, or cream. ...
  • Diluted apple cider vinegar. ...
  • Healthy fats. ...
  • Bone broth.

What is the best intermittent fasting window to lose belly fat? ›

A 2023 review of research found that the 16/8 method and 16/8 combined with restricting calories were effective strategies for weight control in adults with overweight or obesity. An eating window starting before noon led to greater weight loss than one that began after noon.

Does coffee break a fast? ›

Technically speaking, eating or drinking any calories breaks a fast. That means it's generally considered OK to drink black, unsweetened coffee or tea, as well as water.

Is intermittent fasting a fad or fact? ›

Intermittent Fasting (IF) has become an increasingly popular fad diet over the past few years. While IF may lead to results such as weight loss, increased cognition and improved overall body composition in the short-term, it is not very sustainable for many interested in making long-term lifestyle changes.

Is it better to fast 12 or 16 hours? ›

A good rule of thumb for those wanting to fast to improve their metabolic and overall health is to leave at least 12 hours between meals – ideally more – on a regular basis, according to Dr Adam Collins, Principal Teaching Fellow in Nutrition at the University of Surrey.

What are the pitfalls of intermittent fasting? ›

Intermittent fasting isn't for everyone. If you're not already used to skipping meals or not eating for an extended period of time, the hunger and fatigue that can occur when starting IF can be difficult to handle. Other side effects can include insomnia, irritability, headaches, and nausea.

Is 16 hours fasting enough for autophagy? ›

Studies suggest the process may start when fasting for 12 to 16 hours and increases with fasting time. There are a variety of health benefits that are associated with fasting and autophagy. Some studies say that autophagy starts within 12-16 hours of not eating.

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