Why is fasting used to help lose weight?
The foods we eat are the initial and ongoing reason why we raise insulin levels in the first place. Over time, our bodies become blind to the signal insulin sends out after a meal (aka insulin resistance). As a result, more insulin is pumped out to get the job done. This persistent call for insulin eventually leads to insulin resistance. While a change in the type of food may be a great start and lead to weight loss, we need to remember that all foods raise insulin (fat has a negligible increase in insulin). With insulin still being signaled to act after a meal, your body is still remaining insulin resistant (the degree to which is determined by how insulin resistant you have become). The goal of fasting is to break the insulin-resistance cycle. The goal is to sensitize the insulin receptors through fasting, which allows for very low levels of insulin for an extended period of time. Remember that obesity is a disease of hormonal imbalance. Hormones like insulin, growth hormone and adrenalin adapt to fasting in a variety of ways. By fasting, you can efficiently reduce your body’s insulin resistance, since it needs both persistent and high levels to remain resistant. Growth hormone (GH) is known to increase the availability and utility of fats for fuel. It also helps to preserve muscle mass and bone density. One of the most potent stimuli for GH secretion is fasting. Over a 5-day fast period, GH secretion more than doubles. Fasting increases adrenalin levels, starting at around 24-hours. 48 hours of fasting produces a 3.6% increase in metabolic rate, not the dreaded metabolic shutdown so often seen in caloric-reduction strategies (Obesity Code, 240). We have about 40,000 calories of stored fat and about 2,000 calories of stored sugar (Guide to IF, 15). The liver stores 100 grams of glycogen and muscles store about 350-500 grams (Primal Course). 70 in the liver, 220 in the muscle (Body by Science, 27)
Extra Info
Growth Hormone (GH): This hormone plays key roles in the growth of bones during childhood, but also maintains bone health in adulthood. Growth hormone stimulates osteoblast activity, promoting bone formation.
Osteoblasts – these are cells that create new bone. They release proteins like collagen that form the bone matrix (3D scaffolding) and then release minerals (including calcium) that bind to this matrix. When bone surfaces are not undergoing formation or reabsorption, they become lined with old osteoblasts that have flattened. These are then called bone lining cells. Under certain conditions, the bone lining cells can return to become bone-forming osteoblasts again.