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A ketogenic or keto diet consists of high protein, moderate fat, and very low carbs. People who follow a strict keto diet eat less than 50 grams (g) of carbohydrates per day, which forces the body to start using fat-derived ketones for energy instead of glucose (sugar) derived from carbohydrates. This state is called ketosis. It takes two to four days, on average, to get into ketosis. To enter ketosis, about 70-80% of daily calories should come from fat, less than 10% from protein, and only about 5% from carbohydrates or “carbs.” Intermittent fasting before starting a keto diet can help speed up the process of getting into ketosis.
Read on to find out what you need to know about getting into ketosis, the timeline of ketone effects, what you can and can’t eat on a keto diet, signs that you’re in ketosis, ways to get into ketosis faster, and the potential risks of staying. on a strict keto diet for long periods.
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Getting Into Ketosis: A Timeline of Ketone Effects
The human body’s metabolism uses glucose for energy (glycolysis) before it uses fat. Therefore, sugar molecules from carbohydrates stored in the body as glycogen must be consumed before ketosis begins. Without burning stored glycogen (sugar) for fuel, your body enters ketosis as it gradually switches from using glucose for energy to using fat for fuel.
There is no one-size-fits-all formula for determining exactly how many daily carbs make the difference between entering ketosis or not. That said, eating less than 50 grams of carbs per day is generally considered a ketone-producing diet. Full keto adaptation, in which your body uses fat as its preferred fuel source during physical activity, may take a few weeks or even months.
The timeline of ketosis can vary greatly depending on various factors, such as:
- The amount of glycogen stored in reserve when a person starts a keto diet
- Age (younger people enter ketosis faster)
- Body weight
- Exercise habits
- Basal metabolic rate
Certain illnesses that affect the thyroid (hypothyroidism) can slow metabolism and affect how long it takes to get into ketosis. Ketogenic diets may change the way the thyroid functions.
Older adults and people with health problems that slow their metabolic rate usually take longer to enter ketosis. Always talk to a healthcare provider before starting a ketogenic diet, especially if you have underlying medical conditions.
The exact timeline for fat loss on a keto diet is not set in stone and varies from person to person. During the first 24-hour window and the next few days on a keto diet, the majority of weight loss is water, not fat. Hypothetically, fat loss due to ketosis begins when the body begins to burn fat deposits for energy. There is mixed evidence and ongoing debate about the fat burning superiority of keto diets compared to other weight loss plans.
Getting into ketosis and losing weight on a ketogenic diet is a complex metabolic process; more research is needed to fully understand how it works.
To see a nutritionist
If you’re thinking about starting a regimented keto diet at home, talk to a healthcare provider and consult with a registered dietitian (RD) or registered dietitian nutritionist (RDN) before you fast for the day or make radical changes to the amount of carbs, fats or protein you eat each day.
Signs You’re in Ketosis
Symptoms of ketosis range from flu-like symptoms to “keto breath.” The easiest, science-based way to know if you’re in ketosis is a simple home test using a ketone urine strip. Any color (from pink to purple) on the ketone test strip indicates ketosis.
Symptoms of carbohydrate withdrawal that may indicate you are entering ketosis include:
- accelerated weight loss
- Bad breath (halitosis)
- Changes in appetite
- Constipation or diarrhea
- They were dehydrated from loss of body water
- Dizziness
- Tiredness
- Headache
- Irritability
- Gastrointestinal distress (stomach issues)
- Ketones in the bloodstream and urine
- Muscle cramps
- Muscle weakness
- Sluggishness
- Subpar exercise performance in the first few days/weeks
Is There A Faster Way To Get Into Ketosis?
Fasting for 12 hours is the fastest way to get into ketosis. When starting a very low carb ketogenic diet, the fewer carbs you eat in the first 24 hours and the following days, the faster your glycogen reserves will be depleted and the faster you into ketosis.
Medium chain triglyceride (MCT) oil supplements may help you get into ketosis faster. In 2018, a study found that keto-induction was faster with MCT supplementation. Within the first 24-72 hours after initiating a keto diet, researchers found that when study participants got 80% of their calories from fat, 13-17% from protein, and 3-6% from carbohydrates – and they also took MCT oil – they would get into ketosis faster than people on the same keto diet who didn’t take supplemental MCT oil.
Ketosis and Diet: What’s Safe and What’s Potentially Dangerous?
It is difficult to answer the question, “Is ketosis dangerous?” with scientific certainty. Most of the studies on what is safe and potentially dangerous regarding ketosis and keto diets are of low quality and lack large samples.
Due to the lack of sufficient high-quality clinical evidence showing that keto diets are safe and without potential harm, there are ongoing debates about whether the benefits of very low carbohydrate ketogenic diets outweigh the -high in unhealthy fats than its risks.
In general, current research shows that it is safe to be on a strict keto diet and in ketosis for about 8-12 weeks. After 12 weeks, potential risks and dangers tend to increase. Although this topic remains controversial, accumulating evidence suggests that the long-term health risks of very low-carbohydrate ketogenic diets outweigh the benefits for most people.
Long-term adverse effects of being in ketosis for long periods of time include:
Research suggests that eating a low-carbohydrate ketogenic diet during pregnancy increases the risk of neural tube defects in newborns, even when taking folic acid supplements.
Ketogenic diets are usually high in red meat, processed meat, and saturated fats, which are associated with an increased risk of chronic kidney disease, heart disease, atherosclerosis (plaque build-up in arteries), cancer, diabetes, Alzheimer’s disease, and other illnesses . In addition, keto diets are low in health protective foods such as fruits, vegetables, legumes and whole grains.
Summary
Ketosis is a metabolic state marked by your body using fat as fuel. When a person is not on a ketogenic diet, the body’s preferred source of energy is the sugar (glucose) molecules derived from carbohydrates. On a strict low-carb keto diet, the body is deprived of carbohydrates, forcing it to turn fat into ketones, which are used as fuel instead of glucose.
It takes about two to four days to get into ketosis, on average, so that’s how long it takes for glycogen reserves to decrease after someone starts eating a keto diet with less than 50 grams of carbohydrates in the face of the day. Fasting, limiting carbs, and MCT oil supplements can speed up the ketosis timeline.
