A keto or ketogenic diet is a low-carb, moderate protein, higher-fat diet that can help you burn fat more effectively. It has many benefits for weight loss, health, and performance, as shown in over 50 studies
What Is Keto?
Normally, the body uses glucose as the main source of fuel for energy. When you are on a keto diet and you are eating very few carbs with only moderate amounts of protein (excess protein can be converted to carbs), your body switches its fuel supply to run mostly on fat. The liver produces ketones (a type of fatty acid) from fat. These ketones become a fuel source for the body, especially the brain which consumes plenty of energy and can run on either glucose or ketones.
When the body produces ketones, it enters a metabolic state called ketosis. Fasting is the easiest way to achieve ketosis. When you are fasting or eating very few carbs and only moderate amounts of protein, your body turns to burning stored fat for fuel. That is why people tend to lose more weight on the keto diet.
Advantages Of The Keto Diet
The keto diet is not new. It started being used in the 1920s as a medical therapy to treat epilepsy in children, but when anti-epileptic drugs came to the market, the diet fell into obscurity until recently. Given its success in reducing the number of seizures in epileptic patients, more and more research is being done on the ability of the diet to treat a range of neurologic disorders and other types of chronic illnesses.
Comparing Kind of Diets
Standard American, Paleo, & Keto Diets (As a % of total caloric intake)
The key distinction between the keto diet and the standard American or Paleo diets is that it contains far fewer carbs and much more fat. The keto diet results in ketosis with circulating ketones ranging from 0.5-5.0 mM. This can be measured using a home blood ketone monitor with ketone test strips. (Please know that testing ketones in urine is not accurate.)
How To Formulate A Keto Diet
For most people, to achieve ketosis (getting ketones above 0.5 mM) requires them to restrict carbs to somewhere between 20-50 grams (g)/day. The actual amount of carbs will vary from person to person. Generally, the more insulin resistant a person is, the more resistant they are to ketosis. Some insulin sensitive athletes exercising vigorously can consume more than 50 g/day and remain in ketosis, whereas individuals with type 2 diabetes and insulin resistance may need to be closer to 20-30 g/day.
When calculating carbs, one is allowed to use net carbs, meaning total carbs minus fiber and sugar alcohols. The concept of net carbs is to incorporate only carbs that increase blood sugar and insulin. Fiber does not have any metabolic or hormonal impact and so do most sugar alcohols. The exception is maltitol, which can have a non-trivial impact on blood sugar and insulin. Therefore, if maltitol is on the ingredient list, sugar alcohol should not be deducted from total carbs.
The level of carbs one can consume and remain in ketosis may also change over time depending on keto adaptation, weight loss, exercise habits, medications, etc. Therefore, one should measure his/her ketone levels on a routine basis.
In terms of the overall diet, carb-dense foods like pastas, cereals, potatoes, rice, beans, sugary sweets, sodas, juices, and beer are not suitable.
Most dairy products contain carbs in the form of lactose (milk sugar). However, some have less carbs and can be used regularly. These include hard cheeses (Parmesan, cheddar), soft, high-fat cheeses (Brie), full-fat cream cheese, heavy whipping cream, and sour cream.
Most people require at least half a gallon of total fluid per day. The best sources are filtered water, organic coffee and tea (regular and decaf, unsweetened), and unsweetened almond and coconut milk. Diet sodas and drinks are best avoided as they contain artificial sweeteners. If you drink red or white wine, limit to 1-2 glasses, the dryer the better. If you drink spirits, avoid the sweetened mixed drinks.
A keto diet is not a high protein diet. The reason is that protein increases insulin and can be converted to glucose through a process called gluconeogenesis, hence, inhibiting ketosis. However, a keto diet should not be too low in protein either as it can lead to loss of muscle tissue and function.
The average adult requires about 0.8-1.5 g per kilogram (kg) of lean body mass per day. It is important to make the calculation based on lean body mass, not total body weight. The reason is because fat mass does not require protein to maintain, only the lean muscle mass.
For example, if an individual weighs 150 lbs (or 150/2.2 = 68.18 kg) and has a body fat content of 20% (or lean body mass of 80% = 68.18 kg x 0.8 = 54.55 kg), the protein requirement may range from 44 (= 54.55 x 0.8) to 82 (= 54.55 x 1.5) g/day.
Those who are insulin resistant or doing the keto diet for therapeutic reasons (cancer, epilepsy, etc.) should aim to be closer to the lower protein limit. The higher limit is for those who are very active or athletic. For everyone else who is using the keto diet for weight loss or other health benefits, the amount of daily protein can be somewhere in between.
Having figured out the exact amounts of carbs and protein to eat, the rest of the diet comes from fat. A keto diet is necessarily high in fat. If sufficient fat is eaten, body weight is maintained. If weigh loss is desired, one should consume less dietary fat and rely on stored body fat for energy expenditure instead.
For individuals who consume 2,000 calories a day to maintain their weight, daily fat intakes range from about 156-178 g/day. For large or very active individuals with high energy requirements who are maintaining weight, fat intakes may even exceed 300 g/day.
Most people can tolerate high intakes of fat, but certain conditions such as gallbladder removal may affect the amount of fat that can be consumed at a single meal. In which case, more frequent meals or use of bile salts or pancreatic enzymes high in lipase may be helpful.
Avoid eating undesirable fats such as trans fat, highly refined polyunsaturated vegetable oils, as well as high amounts of omega-6 polyunsaturated fats.
MCT is a specific type of fat that is metabolized differently from regular long-chain fatty acids. The liver can use MCTs to rapidly produce energy, even before glucose, thus allowing an increased production of ketones.
Concentrated sources of MCT oil are available as supplements. Many people use them to help achieve ketosis. The only food that is uniquely high in MCTs is coconut oil. About two-thirds of the coconut fat is derived from MCT.
Who Should Be Cautious With A Keto Diet?
For most people, a keto diet is very safe. However, there are certain individuals who need to take special care and discuss with their doctors before going on such a diet.
Must Concerns With A Keto Diet
1. Is Keto Safe For Long-Term?
This is an area of some controversy. Though there have not been any studies indicating any adverse long-term effects of being on a keto diet, many experts now believe that the body may develop a “resistance” to the benefits of ketosis unless one regularly cycles in and out of it. In addition, eating a very high-fat diet in the long-term may not be suitable for all body types.
2. Cyclical keto diet
Once you are able to generate over 0.5 mM of ketones in the blood on a consistent basis, it is time to start reintroducing carbs back into the diet. Instead of eating merely 20-50 g of carbs/day, you may want to increase it to 100-150 g on those carb-feeding days. Typically, 2-3 times a week will be sufficient. Ideally, this is also done on strength training days on which you actually increase your protein intake.
This approach of cycling may make the diet plan more acceptable to some people who are reluctant to permanently eliminate some of their favorite foods. However, it may also lower resolve and commitment to the keto diet or trigger binges in susceptible individuals.