The most dramatic changes happen within the first three days of the fast. This happens because the body switches from different sources of fuel. Normally, the primary form of energy the body uses for energy is glucose, a sugar. This is converted by respiration into energy. Throughout the day, the liver stores excess sugar in a form called glycogen that we use as energy levels fall between meals. Usually there is enough to last 8-12 hours, and is usually used up completely within the first 24 hours of fasting.
Once these stores are gone, the body shifts over to ketosis – the use of fatty acids as fuel instead of glucose. This shift generally starts on the second day of fasting and is completed by the third. During this time, no glucose is available and energy from fat conversion is insufficient, so it accesses glucose from two different sources – glycerol, available in the body's fat stores and amino acids in the muscle tissue, using them in the liver for gluconeogenesis ( glucose production ). Around 60 and 84 grams of protein are used on this second day.
By the third day however the ketone production is enough to provide nearly all the energy the body needs and the body's protein is preserved. However, some bodily functions are unable to function with this form of energy, so 18 – 24grams of protein is used daily to supply it. This is an evolutionary process which protects muscle tissue and vital organs from damage during times of insufficient food availability.
From the third day onwards, the breakdown of fat continues to increase, hitting its peak on the tenth day. During these seven days after the body has switched over to ketosis is where the body begins to seek out all non-body proteins sources e.g. Bacteria and viruses. Also, during this time the body is in a similar state as when we sleep – it's a rest and detoxification cycle. The body focuses on removal of toxins from the body and it regenerates damaged tissues and organs.
Many people mistake fasting as starvation. Starvation occurs after around 42 days, when the body runs out of non-essential proteins, and has to use the essential ones, such as vital organs. The body benefits after around 5 days of fasting, for 7 – 14 days the body begins to heal and then during the 14 – 21 days the body has pretty much regenerated much of itself. Fasts longer than this are not only unnecessary, but can become unhealthy.
People have claimed to lose around a lb for each day of fasting. Most of this however is water, and will be regained after the fast is broken. Breaking the fast is the hardest part of it. This probably requires the most willpower of all. One must accept that the body has become unaccustomed to digestion, so foods must be easy to break down and digest. Many people start on broths and soup, and then move on to soft foods before eating properly. The fast reduces the hunger of most people, and because of this, people tend to keep most of the weight that they have lost off. I believe that fasting is a very effective & healthy way to diet.
