Fasting. It is a word that frightens many, owing to the myth that humans require three or more meals a day, every day. Most people do not fast on a regular basis, except for reasons of faith or belief. Ramzan springs to mind. However, fasting, if done right, potentially holds the key to healthy weight loss.
Intermittent fasting is a diet which consists of periods of fasting followed by food intake within a set time. The usual method is the 16/8 method, which entails fasting for 16 hours, followed by an eight hour eating period. There are more extreme variations, with fasting periods of up to two days. Within this eating period, depending on your fitness goals, you can intake your daily calories, a caloric deficit if you want to lose weight.
What most people fail to understand is that the human body has evolved to handle long periods of fasting without adversely affecting health. This is a result of our ancestors in the Neolithic era having to undergo sustained periods of low or no food intake before they can gather enough for a proper meal. Only after the agricultural revolution 10,000 years ago did we adopt the pattern of regularly eating three meals a day.
Intermittent fasting can have several health benefits. During the period of fasting, several physiological changes can be observed, in stages.
1. Feeding: During meals, insulin levels are raised. This allows uptake of glucose into tissues such as the muscle or brain to be used directly for energy. Excess glucose is stored as glycogen in the liver.
2. The post-absorptive phase (6-24 hours): After beginning fasting. Insulin levels start to fall. Breakdown of glycogen releases glucose for energy. Glycogen stores last for roughly 24 hours.
3. Gluconeogenesis (24 hours to 2 days): The liver manufactures new glucose from amino acids in a process called “gluconeogenesis”. Literally, this is translated as “making new glucose”. In non-diabetic persons, glucose levels fall but stay within the normal range.
4. Ketosis (2-3 days after beginning fasting): The low levels of insulin reached during fasting stimulate lipolysis, the breakdown of fat for energy. The storage form of fat, known as triglycerides, is broken into the glycerol backbone and three fatty acid chains. Glycerol is used for gluconeogenesis. Fatty acids may be used for directly for energy by many tissues in the body, but not the brain. Ketone bodies, capable of crossing the blood-brain barrier, are produced from fatty acids for use by the brain. After four days of fasting, approximately 75 per cent of the energy used by the brain is provided by ketones. The two major types of ketones produced are beta hydroxybutyrate and acetoacetate, which can increase over 70 fold during fasting.
5. Protein conservation phase (5 days): High levels of growth hormone maintain muscle mass and lean tissues. The energy for maintenance of basal metabolism is almost entirely met by the use of free fatty acids and ketones. Increased norepinephrine (adrenalin) levels prevent the decrease in metabolic rate.
These stages, cumulatively lead up to the body utilising its stored fat for energy, in the absence of its preferred energy source, glucose. The elevated growth hormone levels ensure that muscle tissue is preserved during the fasting stage.
The Ramadan fast is one of the most widely followed kinds of intermittent fasting, which consists of fasting from sunrise to sunset. An important lesson can be learned from the practice of Ifthar followed by Muslims undertaking Ramadan fasting — always break your fast with a light meal, consisting mostly of fruit.
The epidemic of unhealthy weight cannot be ignored, and finding convenient ways to lose weight is gaining importance. An intermittent fasting diet is a simple, effective and healthy way to shed that extra fat, and take you one step closer to your dream body.