Fasting is an ancient food restriction method that has become popularised for its many benefits to weight loss, health and longevity. While going against your body’s signals to eat during a fast can feel impossible, we are in fact reverting back to the hunter-gatherer lifestyle that saw ancient humans enduring days of prolonged fasting. Nevertheless, fasting remains a challenging dietary change that is difficult to incorporate into the busy modern way of life. This guide can help you adapt and maintain fasting in your lifestyle.

Different types of fasting

Caloric restriction offers numerous health benefits, from weight loss, protection against diseases including diabetes, cardiovascular disease and cancers and increased longevity –all through to the processes of ketosis and autophagy [1]. There are multiple methods to suit any lifestyle, from spontaneous meal skipping for those beginning their fasting journey, to extreme 36-hour prolonged fasts. A happy medium can be found in intermittent fasting (IF), which alternates between regular periods of fasting and feasting and is especially easy to adapt to busy lifestyles as it does not restrict your diet during feast hours. Intermittent fasting comes in many forms: the 5:2 involves reducing your calorie intake for two days a week then eating unrestricted for the remainder of the week; the one meal a day fast (OMAD), also known as the ‘Warrior fast’, involves only eating one huge meal a day; while Time Restricted Eating (TRE) consists of daily alternating windows of fasting and feasting. TRE involves the least commitment as its fasting windows range from 12 hours with the short 12:12 fast, to 20 hours with the challenging 20:4 fast [2]. The 16:8 is one the most popular forms of TRE that follows the body’s natural circadian rhythm, consisting of 8 hours of feasting during the day followed by 16 hours of fasting overnight. Most people complete some form of fast overnight since it is physically impossible to eat while you are sleeping! This means you can easily achieve the 16:8 by extending this natural fast by a few hours in the morning and night. While extreme prolonged fasts are best avoided by beginners, experiment with different fasting methods until you find the one that fits perfectly into your lifestyle.

Setting realistic goals

Unlike fad diets, caloric restriction is a sustainable weight loss method that works over the long term by placing the body under nutrient stress, triggering the metabolic process of ketosis (fat burning). However, it is possible to overdo it and place too much stress on the body, causing fatigue and mental strain and undoing fasting benefits. For example, aiming for a 24-hour fast for a quick weight loss fix as a beginner may lead to adverse side effects. Instead, align your fast with your long term weight loss goals while remaining realistic. Set small, frequent intermittent fasting goals that are more easily achievable than insurmountable prolonged fasting. For example, a weekly 12-hour fast is a better compromise. After your first week of fasting, increase your fasting window or frequency each succeeding week until you reach a level that you are comfortable with. By this time, you may already be happy with the weight loss results achieved by shorter fasts and if not, your body will be better prepared to endure prolonged fasting [3].

How to avoid eating during fasting

Until your body becomes used to caloric restriction, it is easy to become preoccupied with the thought of food. Luckily, there are several strategies to avoid this, the key being preparation. Firstly, write down your usual schedule as well as any events that involve eating, fitting fasting in the hours around this to ensure that your social life does not disrupt your fast and vice-versa. Considering that most human bonding revolves around eating, timing your fast around your social life allows you to stay committed to both your fast and your friends. Planning a grocery list and cooking schedule can help you have healthy, fulfilling meals ready for when you break your fast [4].
Another way to prepare for fasting is by eating healthily before your fast or during the feasting hours of an intermittent fast. Eliminating or restricting intake of sugars and refined carbohydrates common in sweets, soft drinks and white bread before a fast is beneficial as these foods negatively impact how the body metabolises fat. Instead, opt for the classic Mediterranean diet with the perfect balance of healthy fats from olive oil, protein from fish and low glycaemic carbohydrates from vegetables and whole grains to compliment your chosen fast [3]. This will also help you feel fuller for longer using less caloric intake.
Allow yourself the occasional indulgence by incorporating your favourite meals and snacks into your feasting hours if it makes you more motivated to remain faithful to your fast – all in moderation of course. It is important to avoid overeating during the periods when you can eat. Over-compensating for fasting periods by eating large, high-calorie meals during feasting periods can leave you feeling lethargic as the body uses up energy to metabolise the sudden reintroduction of food. Managing portion sizes will help you remain in control over your eating, and practising intermittent fasting can even help to reduce appetite [5].
Considering that people tend to eat unhealthy foods in greater amounts when they are bored as a distraction, it is important to remain busy while fasting [6]. For example, increasing your exercise routine during caloric restriction boosts the health benefits of your fast as well as keeping your mind and body occupied and away from food cravings. While strenuous exercise while fasting is not recommend, light aerobic activities like walking and yoga or strength-based workouts for a maximum of one hour per day are ideal. Incorporating a new exercise regime or hobby alongside your fast will distract you from eating as well as help you to achieve holistic health.
Finally, share your caloric restriction goals with others as they can help to keep you in check and offer words of encouragement, be it family or work colleagues depending on the time of day your fast falls. This will hold you more accountable to your weight loss goals, and seeing you reach them may even convert others to the fasting lifestyle [4]!
Alternatively, specialised apps like the longevity app Humanity are available to keep track of your fast 24/7. This can help you set and visualise goals, remind you to eat or fast with alarms and provide nutritional advice, effectively gamifying your fast and making it more fun to complete.
[1] https://www.nejm.org/doi/full/10.1056/nejmra1905136 
[2] https://fasting.com/fasting-methods/intermittent-fasting/ 
[3] https://fasting.com/fast-start-articles/a-beginners-guide-to-fasting/ 
[4] https://rb.gy/uroxzt
[5] https://onlinelibrary.wiley.com/doi/abs/10.1002/oby.22518 
[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4381486/