What is intermittent fasting?
Intermittent fasting, in its simplest form, usually involves skipping a meal or two. It can also be performed safely for longer periods. Intermittent fasting may be seen as an extension of the philosophy of only eating when hungry. Many people simply by skipping breakfast or dinner due to lack of hunger perform an 18 hour fast.
Consumption of fluids is important while fasting to avoid dehydration. This may include water, bone broth, tea and coffee. While strictly speaking, kilojoule containing beverages are not in keeping with a fast, many people find them useful. Milk content of tea and coffee should however, be kept to a minimum.
Will I be hungry?
A lot of our hunger impulse arises from lack of accessible energy, where our body is not able to effectively use the energy from our fat stores. After 1 or 2 weeks on the Transformation Diet, your body will have started to train the processes responsible for burning fat. When this occurs, your body will be able to tap into your fat stores for energy even when you are not regularly eating. In this state, which is called ketosis, there will be minimal hunger while intermittent fasting. Many people are surprised at how easy it is. In fact, most people on the Transformation Diet end up only eating two meals a day simply because they are not hungry.
Don’t we need to eat regularly to maintain our metabolism?
There is no science to this. In fact, it is common sense that if we want to lose weight, we should eat less often. Both habit and culture contribute to the desire to eat three or more times per day. Many patients on the Transformation Diet still eat three meals a day despite not being hungry out of habit. By learning to respond to the sensation of true hunger, and not eating simply out of habit, many patients significantly increase their rate of weight loss.
How long should I fast for?
This is really a question of whether you should skip one meal (16 hour fast) or two (24 hour fast). Most people find a 16 hour fast quite easy once they have achieved ketosis. It comes down to a matter of personal preference and results. We recommend that you start with a 16 hour fast, and if still desiring a greater rate of weight loss, increase to a 24 hour fast.
How often should I fast?
This is entirely up to personal preference. It is reasonable to start with 2 non consecutive days per week. There are no harms with doing it more often, and many patients experience great results with a daily 16 hour fast.
What do I do?
A typical example is eating dinner at 7pm and then not eating again until at least lunchtime the next day. You are free to drink bone broth, tea, coffee or water as desired. You may eat between lunchtime and about 7-8pm that night. Having said that, the start time of a fast is flexible, and should be determined by whatever works best for you.
Alternating periods of normal food intake with prolonged periods (usually 16-48 hours) of restricted or no food intake have been described. Different variants of fasting diets include:
- 5:2 diet – calorie restriction for two non-consecutive days a week and unconstrained eating the other five days
- Alternate-day fasting
- Random meal skipping
- Feeding window – only eat during a set ‘window of time’ every day (e.g. from 12 p.m. to 6 p.m.)
Although interest in fasting is increasing, due to reported benefits on metabolic health and physiological and molecular markers of health and longevity, clinical relevance remains low because of insufficient human data, lack of controlled trials and limited safety data.
One interesting aspect associated with fasting diets is its proposed benefits on longevity, or ‘delayed ageing’. Fasting catalyses regenerative processes in the body that reduce oxidative damage and inflammation, improve cellular protection and optimise energy metabolism.Caloric restriction has been shown to extend lifespan in multiple animal models, however it is not known whether fasting can extend human lifespan, and if it can, which variant of fasting is optimal.
Of course, the inability of most people to adhere to diets, especially restrictive diets such as fasting, somewhat limits fasting’s feasibility. However, emerging evidence regarding ‘fasting-mimicking’ diets, characterised by consumption of a low-calorie diet for five days straight each month instead of completely fasting, suggests that periodic reduction of calorie intake can also reduce markers and risk factors for aging and age-related diseases.