Ketone bodies are by products of incomplete FFA breakdown in the liver. Once they begin to accumulate fast and reach a certain level they are released , accumulated in the bloodstream and cause a state called グラマラスパッツ. As this occurs there is a decrease in glucose production and utilization. There is also less reliance on protein to meet energy requirements by the body. Ketogenic diets are often referred to as protein sparing as they help to spare LBM whiled dropping body fat.
In regards to ketogenic diets there are two primary hormones- insulin, glucagon that need to be considered. Insulin can be described as a storage hormone as it’s job is to take nutrients out of the bloodstream and carry them to target tissues. Insulin carries glucose from the blood to the liver and muscles, and it carries FFA from the blood into adipose tissue (stored fat triglyceride). On the other hand glucagon breaks down glycogen stores (especially in the liver) and releases them into the blood.
When carbs are restricted or removed insulin levels drop while glucagon levels rise. This causes enhanced FFA release from fat cells, and increased FFA burning in the liver. This accelerated burning of FFA in the liver is what leads to ketosis. There are a number of other hormones involved with this process as well.