In biology, ketosis is a state of the organism characterised by elevated levels of ketone bodies in the blood, by the processes of lipolysis and beta-oxidation.
Ketone bodies are formed from excess amount of fat break down. Some of these ketone bodies such as acetoacetate and ß-hydroxybutyrate can also be used for energy.
When glycogen stores are not available in the cells, fat (triacylglycerol) is cleaved to give 3 fatty acid chains and 1 glycerol molecule in a process called lipolysis.
Most of the body is able to utilize fatty acids as an alternative source of energy in a process in which fatty acid chains are cleaved by coenzyme A (CoA) to form acetyl-CoA, which can then be fed into the Krebs cycle.
Acetyl-CoA can only enter the Krebs cycle bound to oxaloacetate. When carbohydrate supplies are inadequate to maintain blood glucose levels, the liver naturally converts oxaloacetate in the liver to glucose via gluconeogenesis for use by the brain and other tissues.
Excess acetyl-CoA in the liver is used to produce ketone bodies, leading to a state of ketosis. During this process, a high concentration of glucagon is present in the serum, which inactivates hexokinase and phosphofructokinase-1 (regulators of glycolysis) indirectly, causing most cells in the body to use fatty acids as their primary energy source.
The brain cannot use fatty acids for energy because the fatty acids cannot cross the blood-brain barrier. However, the ketone bodies produced in the liver can cross the blood-brain barrier. In the brain, these ketone bodies are then incorporated into acetyl-CoA and used in the Krebs cycle.
Excess ketone bodies will slowly decarboxylate into acetone. Acetone is excreted in the breath and urine.
Ketosis should not be confused with ketoacidosis (diabetic ketoacidosis or the less common alcoholic ketoacidosis), which is severe ketosis causing the pH of the blood to drop below 7.2.
Ketoacidosis is a medical condition usually caused by diabetes and accompanied bydehydration, hyperglycemia, ketonuria, and increased levels of glucagon. The high-glucagon, low-insulin serum levels signal the body to produce more glucose via gluconeogenesis and glycogenolysis, and ketone bodies via ketogenesis. High levels of glucose causes the failure of tubular reabsorption in the kidneys, causing water to leak into the tubules in a process called osmotic diuresis, causing dehydration and further exacerbating the acidosis.
Understanding Ketosis Symptoms
Many dieters develop ketosis symptoms that let them know ketones are present. For many people beginning a low-carb diet, ketosis kicks in after a few days with minimal carbohydrate intake. In fact, most low-carbohydrate plans have an initial phase in which dieters take in extremely low amounts of carbohydrates (usually less than 25 grams per day) in order to kick start ketosis.
You can test for the presence of ketones in the urine using ketosis strips. Many symptoms may also indicate that your body is in ketosis.
Early Stages
Ketosis symptoms change depending how long you've been in the state. In the early stages of ketosis, the symptoms may be a bit unpleasant. However, as your body adapts to the presence of ketones in the bloodstream, symptoms lessen and change. Early ketosis symptoms usually last for several days or up to a week in some people. This typically continues until the body is used to burning fat instead of glucose. After the several days, the levels of ketones in the body will lessen, but that does not mean you are no longer losing weight. It simply means your body has found a balance and is no longer producing excess ketones.
Early stage symptoms include the following:
- Tiredness or fatigue
- Headache
- Feeling thirsty all the time
- Dry mouth
- Ketosis breath, which smells vaguely fruity and not terribly pleasant
- Metallic taste in the mouth, particularly on the back of the tongue near the molars
- Weakness
- Dizziness
- Nausea or stomach ache
- Sleep problems
- Cold hands and feet
- Frequent urination
Ongoing States
As your body adapts to ketones, your symptoms may change or abate altogether. If you are using ketosis strips, your urine may still show ketones present, although probably in far lower concentrations. This is nothing to worry about. The amount of ketones in your urine does not correlate to the rate of weight loss.
As your body adapts to ketones, you may notice the following:
- A "buzzed" feeling
- Increased energy
- Normalized urination frequency
- Better sleep
- Euphoria
- Clear thinking
Sometimes low-carb dieters never seem to reach ketosis, or at least never have the urine test strips indicate excess ketones. This could be because exercising has used up the excess ketones or the urine is diluted from drinking a lot of water. This doesn't mean these people aren't burning fat, just that they aren't registering as technically being in ketosis.
Dealing with Ketosis Symptoms
Ketosis is a common part of low-carb dieting, but it isn't always a pleasant one. If you find yourself having trouble getting through this period, there are some things you can try that might ease symptoms:
- Snack regularly. Having a protein-rich snack like a piece of chicken may ease the headache and other symptoms.
- Take vitamins and minerals. Especially with the lack of fruits and vegetables on a low-carb diet, it's vital to take a good vitamin and mineral supplement to keep your body in a healthy balance.
- Try a protein shake. Protein shakes with amino acid supplements can also be helpful for reducing symptoms of ketosis and easing this transition. Many different kinds of amino drinks are available and often are marketed to body builders.
- Drink plenty of water, which will freshen breath and keep you hydrated.
Is Ketosis Dangerous?
Some suggest ketosis is an unhealthy condition. Studies show differently, however. A 1983 study published in Metabolism showed ketosis was well-tolerated. Anotherstudy in the Journal of Nutrition and Metabolism in 2002 showed ketosis had a positive effect on blood fats and did not increase risk of cardiovascular disease.
Ketosis Is a Signal
The most important thing to remember is that the unpleasant ketosis symptoms are temporary and will pass within a week or so. Try to focus on the fact that this less-than-perfect feeling is just a sign that you are burning fat and well on your way to losing weight.
Published By:
Angela Lumley
Sources:
http://www.news-medical.net/health/Ketosis-What-is-Ketosis.aspx
http://diet.lovetoknow.com/wiki/Ketosis_Symptoms
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