You’ve heard of the keto diet. Everyone from Lebron James to the Kardashians has used the low-carbohydrate, high-fat diet for reasons like performance and weight loss.
The goal of the keto diet is to get the body producing ketones– a fundamentally different energy source than the carbohydrates and fats your cells typically use for energy. It can take several days of ketogenic eating before the body starts to produce ketones. And the time it takes to get into ketosis varies between individuals.
“Keto” comes from the word “ketogenic.” This is a nuanced term meaning that the body is producing ketones from fat. When blood ketone levels exceed 0.5mM, the body has achieved “ketosis.” So ketosis can be achieved either through diet or fasting (meaning the body is producing its own ketones to be ketogenic), or also by consuming products that raise blood ketone levels.
Limiting carb intake and protein intake encourages the body to burn fat–and thus produce ketones. Importantly, restricting proteins as well as carbohydrates limits the amount of substrate available for gluconeogenesis. This is the process of making glucose from non-glucose molecules such as lactate, glycerol, or protein.
Because the ketogenic diet is low-carbohydrate, it often gets confused with other low-carb diets out there. Just because a diet is low carb doesn’t mean it’s keto. It’s subtle differences in the macronutrients provided in the diet determine if the diet is ‘ketogenic.’
A macronutrient is something humans consume in large quantities to provide the bulk of energy to the body. The primary macronutrients are carbohydrates, fats, and proteins. For a diet to be ketogenic, it must be high in fat, low-moderate in protein, and very low in carbohydrates.
Keto Diet for Weight Loss
The ketogenic diet can be used to help with weight loss and also to treat some diseases (discussed in detail elsewhere). Recently, the number of positive keto diet reviews has increased. The rising popularity of the diet has led to a demand for further randomized control trials to study its long-term efficacy. A key reason why the ketogenic diet helps weight loss is that it decreases hunger. This makes it easier to maintain a calorie deficit. It is important to stress that the overconsumption of calories will prevent weight loss, regardless of the macronutrient composition.
How to Start a Ketogenic Diet
Don’t try to start the diet gradually. If carbohydrate intake is moderately-low, blood sugar levels may not be enough to fuel the brain, and the presence of carbohydrate in the diet might still be enough to stop the body from making ketones.
The main objectives when starting the ketogenic diet are to:
- Restrict carbohydrates to 20 digestible grams per day or less – a strict low-carb diet
- Consume plenty of fiber
- Restrict protein to moderate levels. If possible, stay at or below 0.45 grams of protein per day, per lb of body weight (1g/kg). So about 70 grams of protein per day if you weigh ~155 lbs (~70kg). If your goal is to lose weight, aim for 1 gram of protein per kg of your target weight
- Consume fat until you are satiated
Tips for Starting the Ketogenic Diet
- Make a keto diet menu. It’s a good idea to keto meal plan before starting the diet. Make a shopping trip to stock up on a range of foods that are low in carbohydrates and high in fat
- Use an app to track macronutrient intake. Apps such as MyFitnessPal are great to get an idea of the macronutrients in common foods. There is also a range of special online keto diet calculators
- Search for a few keto recipes to adapt cooking methods. Due to the high-fat consumption required to get into ketosis, it may be beneficial to change daily staples or cooking methods. Keep an eye out for coconut oil, heavy cream, and lots of cheese
- Make an approved list of keto foods and eliminate carbohydrate-rich foods. It will be easier to follow the diet by throwing out any foods to avoid. It’s recommended to check the labels for hidden added sugars
- Consider starting the ketogenic diet within a short period (16-36 hours) of fasting (consuming zero calories). Fasting depletes carbohydrate stores and can accelerate ketone production. Click here to read more about fasting protocols
- Gentle cardio exercise (~30 minutes) or some short high-intensity intervals (10-second sprints) can deplete carbohydrate stores and speed up ketone production.
Who Should Avoid a Ketogenic Diet?
Following a ketogenic diet may not be suggested for people with the following medical considerations:
- Kidney failure
- Impaired liver function
- Impaired fat digestion (gallbladder disease, gastric bypass, pancreatitis)
Genetic defects in metabolism (CPTI/II deficiency, beta-oxidation defects, fatty acyl dehydrogenase deficiency)
Potential Side Effects of the Ketogenic Diet
When starting a ketogenic diet there can be a period of 2-3 days where blood glucose levels are low, but ketone production has not reached a sufficient rate to provide enough fuel for the brain.
This can result in a series of symptoms, known as the keto flu, which include:
- Muscle cramps
Exogenous ketone supplements, such as HVMN Ketone, and medium-chain triglycerides can be used to reduce symptoms of keto flu. They provide the brain with a source of energy without carbohydrate consumption. These supplements increase the levels of ketones in the blood artificially. Exogenous ketones do not increase the body’s ketone production (called endogenous ketones) and can inhibit32 the release of fatty acids from adipocytes.
It can be initially tricky to adjust food intake to ensure adequate nutrition when following a ketogenic diet. Also, some people find the diet isn’t sustainable due to individual differences in metabolic state or lifestyle. If the diet does not provide the correct balance of macro and micronutrients, some individuals develop other symptoms beyond the keto flu after the adaptation period. These include:
- Bad breath
- Difficulty in maintaining physical performance
- Hair loss
- Elevated blood triglycerides or cholesterol
To treat these symptoms, ensure the diet provides enough calories and micronutrients. Many people reduce fruit and vegetable consumption on a ketogenic diet (due to carbohydrate content). This means it is easy to become deficient in vitamins and to under-consume fiber.
The ketogenic diet can alter the way that the kidneys excrete electrolytes (such as sodium), so electrolyte supplementation can reduce the side effects of an electrolyte imbalance.