How to Transition Through Every Ketosis Phase: Part 3

Adapting your body to burn fat instead of carbs involves five specific phases. These phases happen in a predictable order that have been researched and studied. Scientists documented the body’s transitions by entering patients into a study where they fasted for forty days. Each phase marks changes in blood chemistry and occurs at specific, scientifically predictable times. With hopes of not overwhelming you, I used three blogs to cover all five phases. In each phase I reviewed where you are in the time since your last carbohydrate, and what fuel source your body is using: ketones versus glucose. I also take note of your brain-fuel in each ketosis phase.

This is the third article covering ketosis phases four and five. Check out part one and part two for the first three phases. This post takes us through keto-adaption.


  • STATUS: Your fuel is now a blend of ketones and glucose. Gradually more sections use ketones as fuel.
  • BRAIN: Powered mostly by glucose, but a few cells use ketones.

This phase focuses on converting stubborn parts of your body to burning fat for fuel. Your ketone resistant cells begin transitioning. By Phase 4 your liver is really good at making ketones from fat. Your blood abounds with these compounds because all liver cells turned on their ketone-producing engines. Slowly the rusty, unused cell parts that make and burn ketones have come to life. If we checked your blood, we would find a hearty amount of ketones ranging from 2-3 mMol/dl.

As the liver pumps out a steady stream of this fuel, the rest of your body is still getting used to processing ketones. Over the two weeks of Phase 4, your ketone efficiency catches up with your liver’s abundant production. By the end of this ketosis phase, your blood ketones will settle into the 0.5-1.5 mMol/dl range.

Now might be a good time to remind you why in the world those ketones are in your urine. Weren’t you supposed to make ketones to fuel your body? Why are they in your urine? Why didn’t we keep them all circulating in the blood?

When you are in Phase 4, the mismatch between how well your liver makes ketones and how efficiently the rest of your body uses them leaves you with too many. Your kidney closely watches your body’s chemistry. Too many ketones trigger the kidney to pass them into the urine. The kidneys and your lungs act as an overflow valve for the extra.

Before you get disappointed about wasting those valuable ketones, keep in mind, they used to be fat calories. You are literally peeing out extra calories! What a magical weight loss plan! Right?

By the end of Phase 4, nearly every cell has processed its own ketone. Your cells may not yet use this fuel steadily, but all of them activate their ketone burning furnaces. Even your most resistant organs have a few cells running on this fuel.

If you kept those carbs less than 20 grams per day, your storage tank is sure to be empty. Your body makes glucose less and less as more cells use ketones instead.

Wait a minute. If you’re not eating carbs and you burned through all the ones you had in storage, where is all this glucose coming from?

ANSWER: It is coming from your fat too. Your fat chains, called fatty acids, travel in groups of three. These three chains are held together by a little glucose-based molecule. Your liver clips off the fat to turn into ketones. A tiny amount of glucose is left over. This tiny source of glucose is saved for your stubborn organs that have a difficult time switching over to pure ketones.


STATUS: Your fuel is mostly ketones with a sprinkle of glucose.
BRAIN: Powered mostly by ketones, but still uses glucose.

Phase 5 is a when your body becomes the well-oiled machine it was designed to be. Each mitochondrion that can use ketones now efficiently handles this fuel type. Thanks to the steady, constant supply of ketones your cells efficiency to process them increased. They are produced and burned at almost equal rates. Because your production and usage are better matched, your ketones no long circulate as long. Phase 5 is marked by a significant drop in your blood ketones. Subsequently, the amount spilling into your urine drops, too.

In a rare moment, your ketone production and usage match perfectly, leaving no extras in your urine. This can be tricky if you are only checking urine ketones. Did your ketones stop showing up in your urine because you ate a bunch of carbs? Drank booze? Maybe the bottle of strips was left open and went bad? Or did your urine ketones stop appearing because your system had a perfect match? Rest assured, the first three options are much more likely. In previous phases, the perfect matched situation was not an option. In Phase 5, it is an option.

Phase 5 is the holy grail. Once your brain reaches this state, you will better appreciate all the hype surrounding a ketosis lifestyle. It borders on euphoric. When patients enter Phase 5, their depression symptoms lift, their focus improves, their attention lasts longer, their sleep is more restful, and their energy is contagious.

How do you get to Phase 5?

There is a fast way and a slower way. The fast way is a strict fast. That is not a play on words. I am referring to an absence of foods. A strict fast is a time of no calories. Only water, tea, or coffee. That’s all. Strictly limit yourself to only those items, and you will be at Phase 5 in about 30 or 40 days. That’s a tough sell.

I DO NOT recommend this option; especially if you are eating a high-carbohydrate diet right now. High carbohydrate means eating over 60 carb grams per day. There are just too many chemistry shifts that have to happen in your system. It’s too unsettling, too uncomfortable, and in many of my chronically ill patients, it’s dangerous.

Instead, transition to Phase 5 using a high-fat diet. Patients transition to a high-fat diet and pee ketones for several weeks. This allows time to adjust. It also provides time to see how much social pressure is placed on eating carbohydrates and low-fat foods.

Screw-ups often happen when first eating high-fat low-carb. They drink alcohol. They eat too much protein. They get stingy on their fat consumption. They mindlessly binge on ice cream after a stressful day. [or maybe that is just me!]

Or someone near them celebrates an occasion with sugary treats, and the temptation becomes too great at the moment. The bottom line?

Changing habits is hard.

Teamwork = The best way to KETO

The idea that a smoker wakes up one day and stops smoking for the rest of his life is a fantasy. That person who ‘suddenly’ quits smoking had months, maybe even years, of thoughts and false starts about quitting before they stopped for good. Their environment played a significant role in their success. If their world tempted them with cigarettes at every turn, their chances of achieving a smoke-free life one year later are unlikely. People in keto transition need support. Without it, temptations win out.

MY GOAL: a healthy life.
Not a sprint to ketone positive urine tests. The key to sustainability is the LONG GAME.

Ultimately, it doesn’t matter whether you get to Phase 5 in 6 weeks or 6 months. Boost your chances of lifelong success by keeping your priorities straight. Remember why you decided to go keto in the first place. Write it down. Say it out loud. Share it with a friend. My personal reason for going keto: Brain fuel, brain fuel, brain fuel.

If you want to learn more about the ketogenic diet, check out the book ANYWAY YOU CAN on Amazon or Audible by Annette Bosworth, MD.

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