28th May 2024

What is intermittent fasting: your FAQs answered

Intermittent fasting has gained popularity in recent years as a flexible and effective approach to weight management and overall health. But what is intermittent fasting? With so much information available, many individuals have plenty of questions about the subject. Today, we’ll address some of the most common FAQs we’ve received about intermittent fasting, giving you the tools and understanding you need to start this popular dietary program with confidence.

What is an intermittent fast?

Let’s start with the basics of ‘what is an intermittent fast’ before we go any further. Intermittent fasting – also frequently referred to as IF – is an eating pattern that cycles between periods of eating and fasting. It doesn’t specify which foods you should eat but rather when you should eat them. However, here at The Fast 800, we recommend eating a Mediterranean-style diet to achieve maximum nutrition. By restricting the time window for eating, intermittent fasting encourages the body to tap into stored fat for energy, leading to potential weight loss and other health benefits.

How does intermittent fasting work?

Now that the question of ‘what is IF fasting’ has been covered, it’s time to look at the science behind its effect on the body. Intermittent fasting works by changing the body’s hormone levels to facilitate weight loss. During fasting periods, when glucose levels are low, the body shifts from using glucose as its primary fuel source to burning stored fat for energy. This metabolic switch triggers the breakdown of fatty acids stored in adipose tissue, leading to increased fat oxidation and potential weight loss.

Intermittent fasting also increases the levels of human growth hormone (HGH) – a hormone that plays a crucial role in growth, metabolism, and muscle maintenance. Higher levels of HGH can promote fat loss, muscle preservation, and overall metabolic health. Research suggests that intermittent fasting may lead to a significant increase in HGH levels, particularly during fasting periods.1

What are the benefits of intermittent fasting?

Intermittent fasting has been associated with numerous health benefits, including:

  • Weight loss and fat loss: Intermittent fasting promotes weight loss and fat loss by creating a calorie deficit through limited eating windows. It preserves lean muscle mass while reducing body weight and fat mass.2
  • Improved metabolic health: Intermittent fasting enhances metabolic health by improving insulin sensitivity, blood sugar control, and lipid profiles. It reduces the risk of insulin resistance, type 2 diabetes, and metabolic syndrome.3
  • Enhanced brain function: Intermittent fasting stimulates the production of brain-derived neurotrophic factor (BDNF), supporting cognitive function, memory, and mood regulation. It may reduce the risk of neurodegenerative diseases.4
  • Increased longevity: Intermittent fasting promotes cellular repair mechanisms such as cell recycling, which may slow the ageing process and extend lifespan. It offers potential benefits for healthy ageing and longevity.5
  • Reduced inflammation: Intermittent fasting reduces markers of inflammation in the body, such as C-reactive protein (CRP) and inflammatory cytokines. It reduces the risk of inflammatory diseases and supports overall health.6

Is intermittent fasting safe?

For most healthy adults, intermittent fasting is considered completely safe. However, it may not be suitable for everyone, especially those with certain medical conditions or women who are pregnant or breastfeeding. It’s essential to consult with a qualified healthcare professional before starting any new diet or fasting regimen.

Will intermittent fasting help me lose weight?

Many people turn to intermittent fasting as a weight loss strategy, and research suggests that it can be effective for shedding excess pounds. By restricting the window of time in which you eat, intermittent fasting can help create a calorie deficit, which is necessary for weight loss. That said, individual results may vary, and other factors such as diet quality and activity level also play a role.

Can I drink water during intermittent fasting?

Yes, staying hydrated is absolutely essential during intermittent fasting. You should always drink water, herbal tea, or other non-caloric beverages during the fasting period to ensure you’re staying hydrated. It’s best to avoid drinks that contain calories, such as sugary beverages or creamy coffee drinks, as they can break your fast and affect your results.

What is an intermittent fasting eating window and what can I eat?

Technically speaking, intermittent fasting is not a diet; therefore, you can eat whatever you want during the eating window. However, we’d recommend you focus on a nutrient-dense, Mediterranean-style diet to support your overall health. Choose foods rich in protein, healthy fats, fibre, vitamins, and minerals, such as lean meats, fish, eggs, vegetables, fruits, nuts, seeds, and whole grains. Avoid processed foods, sugary snacks, and excessive amounts of refined carbohydrates.

How long does it take to see results from intermittent fasting?

Results from intermittent fasting can vary depending on individual factors such as diet, lifestyle, metabolism, and starting weight. Some people may notice changes in weight, energy levels, and overall wellbeing within a few weeks of starting intermittent fasting, while others may take longer to see significant results. It’s always important to remember that everybody is different, so don’t be discouraged if you don’t see results straight away. Trust the process and stick with it.

Can I exercise while intermittent fasting?

Yes, you can and should exercise while intermittent fasting to help maintain muscle mass. You should aim to incorporate a mix of cardiovascular exercise, strength training, and flexibility exercises into your routine. In fact, combining intermittent fasting with regular physical activity can enhance the benefits. When you exercise in a fasted state, your body relies more on stored fat for energy, which may promote greater fat loss over time.

The timing of your workouts can play a role in how you feel and perform while intermittent fasting. Some individuals prefer to exercise during their fasting period, while others find it more comfortable to work out during their eating window. Experiment with different timing strategies to see what works best for your schedule and preferences.

Start your weight loss journey with us

Intermittent fasting can be a powerful tool for improving health and achieving weight loss goals when done correctly and safely. We recommend that you consult a healthcare professional before making any significant changes to your diet or lifestyle.

Looking for more ways to lose weight and maintain a healthy, balanced lifestyle? Explore more about how to achieve your weight management goals with The Fast 800. Our specially designed weight loss programme includes a selection of products and resources developed alongside Dr Michael Mosley and based on years of experience with fasting, ensuring you get information based on medical science.



Ju Young Kim. Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance. J Obes Metab Syndr. 2021 Mar 30; 30(1): 20–31. doi: 10.7570/jomes20065. PMID: 33107442.

Ju Young Kim. Optimal Diet Strategies for Weight Loss and Weight Loss Maintenance. J Obes Metab Syndr. 2021 Mar 30; 30(1): 20–31. doi: 10.7570/jomes20065. PMID: 33107442.

Teresa Vanessa Fiorentino. Effects of Intermittent Fasting on Brain Metabolism. Nutrients. 2022 Mar; 14(6): 1275. doi: 10.3390/nu14061275. PMID: 35334932.

Valter D. Longo. Intermittent and periodic fasting, longevity and disease. Nat Aging. 2021 Jan; 1(1): 47–59. doi: 10.1038/s43587-020-00013-3. PMID: 35310455.

Andrea Mulas, Sofia Cienfuegos, Mark Ezpeleta, Shuhao Lin, Vasiliki Pavlou, and Krista A. Varady. Effect of intermittent fasting on circulating inflammatory markers in obesity: A review of human trials. Front Nutr. 2023; 10: 1146924. doi: 10.3389/fnut.2023.1146924. PMID: 37139450.

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