Many health insurance plans have an out-of- pocket expense maximum. An out-of-pocket expense is a nonreimbursable expense paid by a patient. But out-of-pocket expenses can also include covered expenses that you are responsible for before your health-plan benefits kick in at 100 percent coverage.
The process of ketosis is one of the physiological effects of fasting in which the brain (and some other bodily processes) uses ketones produced from fatty tissues as a fuel instead of the usual glucose. This is called muscle sparing.
However, a large portion of your brain can also use ketones for energy, such as during starvation or when your diet is low in carbs (7). In fact, after only three days of starvation, the brain gets 25% of its energy from ketones. During long-term starvation, this number rises to around 60% (8, 9). In addition, your body can use protein to produce the little glucose the brain still requires during ketosis. This process is called gluconeogenesis.