No. After approximately 8 hours you start making ketones for as long as the glycolytic pathway is not sufficient.
Suppose you wake up at 6:00 am and you eat avocado, chicken breast and a minuscule portion of bread that morning. if you have low carbohydrates intake for more than 4 hours then you spend your Glycogen (your liver's reserve of glucose) at around 8 hours (2 pm or earlier as the reserves of glycogen are low when you wake up). You are in ketogenesis burning fat. You continue to make ketones for as long as the sources of carbohydrates are low.
In patients with resistant epilepsy, treated with ketogenic diets they are in constant ketogenesis. There could be common but easily treatable complications as constipation, hyperlipidemia, hypoglycemia, and acidosis. So it requires monitoring. Requires consulting a doctor.