How long has it been since you last ate ?
People who fast intermittently often eat within an 8 hour block, leaving 16 hours of fasting in between. During that 16 hour stretch their bodies undergo an important change that set them apart from non faster.
Here how it works
When you eat you store some of that energy in the liver as glycogen, But after 10 to 12 hours of not eating your glycogen reserves will be extremely low. As a result you will feel more irritable than normal, a term scientists calls "hangry". The Upside is - with little glycogen left, fat cells in your body release fats into your bloodstream. The fat cells ahead straight to your liver, where they are converted to energy for your brain and body.So you are literally burning fat for survival.
Blood samples shows that people who had fasted for 12-24 hours experience a 60% increase in energy from fat with the biggest change occurring after 18 hours. THIS is the benefit to intermittent fasting. Because it puts you in a state called ketosis. And it's why researchers think intermittent fasting could be the key to longer and healthier life.
The process of burning the fat releases the chemicals called ketone. In the brain ketone trigger the release of an important molecule called BDNF. BDNF helps to build and straighten neurons and neural connections in areas of brain responsible for learning and memory. Which could explain why a boost in ketone production has shown an improve memory in people with early signs of dementia in as soon as 6 weeks.Increasing ketone in the body is also a common treatment for patients with severe epilepsy.
You don't necessarily have to fast to boost your ketone levels. Introducing more fatty foods in to your diets and cutting back carbs can have similar effect. A group of people who tried this method for 3 months not only lost weight and body fat but also saw a decrease in blood pressure and a hormone (IGF-1) that is related to aging and disease. But scientists have discovered that fasting increase ketone levels more.
Ketogenic diets can increase ketone by 4 fold while fasting can increase the levels by 20 fold. As the result fasting compared to a ketogenic diet have more beneficial effect on overall health. Today they are recognized as a way to help keep future generation mentally and physically disease free.