What is a Keto Diet?
A keto or ketogenic diet is low in carbohydrate, high in fat and has an adequate amount of protein. Many studies have shown that it effective in both weight loss and improving metabolic health. The keto diet means that there is little energy from carbohydrates, with fats providing the main source of energy. (1,2)
The body has two different fuel systems, a carbohydrate fuel system and a fat fuel system. Think of this as a hybrid car, where the engine changes from electric to either gas or diesel fuel. In a similar way, your body can change from using carbohydrate as its fuel source, to using fat as its fuel source. When you are using carbs for fuel, your organs and muscles metabolise stored glucose for energy. When you are fueling on fat, you metabolise your stored fats for fuel. Mostly for low level energy, we tend to utilise fats, and for high power or fast tasks, our muscles fuel on glucose. Our brain uses 20% of our total calorie burn each day. Its primary fuel is glucose. When our glucose stores are low, the brain unlike other tissues in the body, cannot fuel on fat. Therefore, under circumstances where we have low blood glucose cirulating, we break down stored glycogen, in the liver, which drip feeds this into the blood to ensure there is sufficent glucose for the brain. Such as during sleep.
Longer periods without carbohydrates from fuel, leads to the depletion of stored glucose (glycogen) and the body then has to alter its metabolism to ensure the blood gucose does not fall. Under these circumstances, glucose is produced for the bloodstream from amino acids and fats; aprocess called gluconeogenesis. This can maintain the blood glucose for very long periods. At the same time, the brain recognising the situation, changes up to 80% of its metabolism to ketone bodies. As the brain cannot metabolise fat, under situations of prolonged fasting, or low carb dietary intake, the brain switches to ketone metabolism. The ketones are made in the liver, from stored fats, and in practical terms we have an endless supply, keeping our brain happy.
Ketones themselves are active chemicals and have many beneficial effects, particularly in the brain. (3) Ketones are also called ketone bodies, and include B-hydroxybutyrate (BHB) and acetoacetate (AA). When you are ketotic, ketones can be easily smelt on your breath. You know that you are ketotic, when you smell ketones.
If you rely solely on your carbohydrate fuel system, your fat fuel system will be long forgotten. When your body needs to activate the fat fueling system, the pathways are poorly developed and the body stutters, rather like a car with dirty fuel. The fat fueling pathways can be developed and trained, but this takes a little time. The amount of time it takes depends on how poor the existing pathways have become. Among other things, it depends on body fat percentage and metabolic rate. The re-programming process, whereby you teach your body how to fuel with fats, is known as fat adaptation.
Fat adaptation can be rapid, if you have been accustomed to intermittently using fat as fuel. But, if you have seldom used your fat fueling system, and you are addicted to carbs, it may take many weeks to fat adapt. "Keto flu" is the feeling that develops as your previously inhibited fat fuel system stutters, stops and then goes. Once you are fat adapted, your body can use whichever fuel is available and you will shift seemlessly from your carb fueling system and your fat fueling system.
Once you are fat adapted, you will be better able to burn fat. You will be able to burn your own fat and lose weight. Your body can run on its own fats for a very long time. And this is the success of a keto diet in weight loss. The body is running on fat. You are losing your own fat and losing weight. If you introduce carbohydrates to the equation, your body will preferentially use carbohydrates as fuel and fat burning will stop.
How do I Eat a Keto Diet?
Knowing and understanding your macronutrients is the key to achieving a keto diet. The proportions of macronutrients are carbs 5-10%, protein 10-35% and fats 60-80%. There isn’t really a standard keto diet and the proportions vary between different plans, the important thing is that it is a high fat diet, with low carbs. In the medical literature, the keto diets are called low carbohydrate high fat (LCHF) diets and tend to use the highest proportions of fats and lowest amounts of protein in the ranges reffered to above. If your basal metabolic rate is 2,000 calories, assuming 5% carbs, 20% protein, 75% fat: You should eat 25 grams of carbs, 100 grams of protein and 167 grams of fat. The exact ratio that is needed varies between individuals, depending on body composition and genetic make-up.
Food containing fats are permitted, as are those containing protein. As it is a high fat diet, it important to ensure that many of the fats eaten are healthy fats, so called unsaturated fats, such as those rich in omega-3s. You should avoid trans fats totally. The protein content of the diet must remain moderate, as too much protein, will prevent ketosis. If you are sedentary, your protein consumption should be 0.4 grams per pound (c 0.9 grams per kilogram) of body weight. If you exercise a lot and are doing resistance training, you may need to adjust the protein composition upwards. Then you can recalculate the fat needed, keeping the carbs at 5%.
It is virtually impossible to reduce your carbohydrate intake to 5% of your daily calories, if you eat super-refined or refined carbohydrates. One muffin alone can contain 60gms of carbs. Foods containing carbohydrate, particularly refined or super-refined carbohydrates are therefore banned. The carbs that you do eat on a keto diet should be unrefined carbs. Most of your carbs should originate from plant sources. When you do eat carbohydrate, make sure that the food has a high fiber content to help your gut health, as much as possible during your keto diet.
Initially it can be difficult to get the composition of the diet right. If you keep a food diary, with a record of the type and amount of food and cross reference the macronutrient composition, this should help. The important part of a keto diet is that carbohydrates need to be between under 25 grams to 50 grams per day, depending on your total energy requirements.
While all diets are restrictive, including a keto diet, there are many different types of foods which can be eaten. Food generally permitted include fish, chicken or turkey breast, meat, avocados, low carb vegetables, some nuts, some seeds, salads, such as tomatoes, spring onions, celery and cucumber, olive oil, eggs, berries, some diary such as natural Greek yoghurt, butter, cheese and cream. A keto diet is not carte blanche to eat all fats; keep the fats healthy.
Fish is carb free and is high in good fats and protein. Chicken or turkey breasts also contain no carbohydrates and have a high level of nutrients such as minerals and B vitamins. Avocados contain high level of monounsaturated fats, which are healthy fats. Most of the carbs in avocados are fiber, reducing your carb load further. Low carb vegetables are very important on a keto diet as they will provide essential fiber and help to keep your microbiome healthy. Low-carb vegetables, or nonstarchy vegetables include kale, spinach, cabbage, zucchini, green beans, asparagus, garlic, broccoli, cauliflower, and mushrooms. Nuts are full of healthy fats, contain lots of fiber and are very low in absorbable carbs. Chia and flax seeds also get a thumbs up as they contain good fats and fiber. Berries are allowed in small proportions; they are lower in net carbs than other fruits. Some dairy is allowed, but dairy can be high in natural sugars, so watch your total carb count. It is high fat dairy, such as cream and cheese that is allowed.
A significant proportion of your daily water intake comes from your food. When adopting a keto diet, this will obviously change, and you need to ensure that you drink more water than normal to avoid dehydration. Your daily water intake should be between 2-3 liters per day. If you are thirsty, you need to heed this warning and adjust your water intake upwards.
Benefits of a Keto Diet
Most people embark on a keto diet to lose weight. (1) A keto diet will result in fat loss, as you preferentially utilise fat over carbohydrate to fuel your body. You can eat nourishing meals; you feel full after the meal and your body is not in starvation mode. There is a decrease in hunger hormones such as ghrelin and cravings are reduced. Research has confirmed the beneficial effects of a keto diet for weight loss. (2)
Keto diets are proven to induce good changes to your metabolism. (2,4) Insulin resistance is reduced, and blood pressure has been shown to fall. Beneficial effects on blood fats have been shown. The metabolic markers of diabetes improve, and remission of diabetes has been achieved. (4) Ketones are a big area of research in the field of anti-aging. Ketones may help to reduce aging by their direct effects on our cells. Laboratory experiments have shown beneficial anti-aging effects of ketone bodies. (3)
A ketogenic diet has been used in a variety of medical conditions including cardiovascular disease, epilepsy, cancer, neurologic conditions including Alzheimer’s disease and chronic pain. Therapy with keto diets is under evaluation and much research is being conducted in this field. A keto diet is a valid and promising option in drug resistant epilepsy in children. Research is rapidly showing benefits, and many authorities are now recommending a ketogenic diet for such children. (5,6) The exact mechanism of the keto diet in epilepsy has not been fully elucidated, but it may be related to the effect on the gut microbiome. (7) A ketogenic diet can provide promising effects in many disorders such as obesity, diabetes, cardiovascular disease and possibly cancer. (1)
A keto diet is also a very method of fat adaptation or activating your fat burning pathway. Fat adaptation is an important step in order to be able to achieve successful intermittent fasting. We use combined techniques in the Diet-Whisperer weight loss plan, fat adaptation with a keto diet, is followed by intermittent fasting.
People who are unaccustomed to using fat as a fuel and are not fat adapted, may find the initial stages of a keto diet rather difficult. The inefficient fat fuel system may manifest in many symptoms, and these are collectively called keto flu. (8) Keto flu can appear to be like flu with symptoms such as headache, fatigue, brain fog, decreased energy, nausea, dizziness, decreased energy, feeling faint and heartbeat alterations. While alarming and troublesome, these symptoms will usually pass, the time varies between 3 -30 days. These symptoms may mean that a keto diet is not suitable for everyone.
People who have diabetes and are on treatment need to embark on a keto diet with the aid of their physician. In this respect, keto diets are no different to any weight reducing diet. Blood sugar and blood pressure will fall following a change of diet and therefore treatment will need to be monitored and adjusted as metabolism improves.
The gut microbiome is essential for health. Gut bugs show changes in obesity and many other diseases. Gut bugs alter with a change in relative ratios of the existing bugs in response to dietary manipulation. Studies in people on keto diets have shown an increase in good bugs such as Akkermansia muciniphilia, but others have shown a decrease in other good bugs. (7) There is insufficient data at present to be didactic about the effect of a keto diet on your gut bugs. However, there is concern, that in the long term that a keto diet may have adverse effects on the gut microbiome, due to the lack of fiber. (9)
There are very rare inherited conditions with disorders of fat metabolism, where either ketones cannot be produced or cannot be used. (11) Such people are not suitable for keto diets. Extreme ketosis can very rarely occur in people who do not have diabetes, if they become severely carbohydrate depleted. The ketone levels rise to extreme levels and this causes a dangerous condition with changes in the blood, so-called ketoacidosis. (10)
Long Term Keto Diets
All restrictive diets have potential long-term problems and a ketogenic diet is no different in this respect. There are also concerns about the effects of long-term carbohydrate depletion and the effect on metabolism. There are also concerns about long term keto, and the potential effect on gut health. We know that the health of gut bugs is critical, we know that they depend on dietary fiber, which is reduced in a keto diet. There is evidence that gut bugs are affected in keto diets, but no-one knows at present what this will mean in the long-term. Staying on a keto diet long-term may pose some risk to long-term health.
Thus, once you have attained your desired weight, it is time to resume a balanced diet. This does not mean introducing super refined carbohydrates to your diet. If you do this, you will be well on the way to gaining all the weight that you have lost. Super-refined carbohydrates should be a very occasional treat, perhaps on birthdays, holidays and occasional celebrations. Super-refined or refined carbohydrates play havoc with your hormones and you will be back on the road to obesity. The type of carbohydrates that you can introduce to your diet are plant carbohydrates. You should eat lots of different plants, with lots of variety. You should eat real food, unprocessed food, food that our ancestors would recognise as food.
Maintenance of your desired weight is one of the biggest challenges to anyone who has achieved their desired goal. The research shows that nearly everyone gains their pre-diet weight after a few years. Disappointing, but true and proven scientifically. That’s why diet companies flourish, you keep going back to them.
Here at the Diet whisperer, we combine keto diets with intermittent fasting in a series of weight loss plans. You choose your weight and we help you to find the tools to achieve permanent weight loss. The whisperer-stable plan, helps to provides a solution for long-term weight maintenance, without the need for long-term restrictive diets.
- Hession M, Rolland C, Kulkarni U, Wise A, Broom J. Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities. Obes Rev. 2009;10(1):36-50.
- Schwingshackl L, Hoffmann G. Comparison of the long-term effects of high-fat v. low-fat diet consumption on cardiometabolic risk factors in subjects with abnormal glucose metabolism: a systematic review and meta-analysis. Br J Nutr. 2014;111(12):2047-2058.
- Han YM, Ramprasath T, Zou MH. β-hydroxybutyrate and its metabolic effects on age-associated pathology. Exp Mol Med. 2020;52(4):548-555.
- Choi YJ, Jeon SM, Shin S. Impact of a Ketogenic Diet on Metabolic Parameters in Patients with Obesity or Overweight and with or without Type 2 Diabetes: A Meta-Analysis of Randomized Controlled Trials. Nutrients. 2020;12(7):2005.
- Ułamek-Kozioł M, Czuczwar SJ, Januszewski S, Pluta R. Ketogenic Diet and Epilepsy. Nutrients. 2019;11(10):2510.
- Martin-McGill KJ, Bresnahan R, Levy RG, Cooper PN. Ketogenic diets for drug-resistant epilepsy. Cochrane Database Syst Rev. 2020;6:CD001903.
- Olson, C.A.; Vuong, H.E.; Yano, J.M.; Liang, Q.Y.; Nusbaum, D.J.; Hsiao, E.Y. The gut microbiota mediates the anti-seizure effects of the ketogenic diet. Cell 2018, 173, 1728–1741.
- Bostock ECS, Kirkby KC, Taylor BV, Hawrelak JA. Consumer Reports of "Keto Flu" Associated With the Ketogenic Diet. Front Nutr. 2020;7:20.
- Murtaza N, Burke LM, Vlahovich N, et al. The Effects of Dietary Pattern during Intensified Training on Stool Microbiota of Elite Race Walkers. Nutrients. 2019;11(2):261.
- Von Geijer L, Ekelund M. Ketoacidosis associated with low-carbohydrate diet in a non-diabetic lactating woman: a case report. J Med Case Rep. 2015;9:224.
- Mitchell GA, Kassovska-Bratinova S, Boukaftane Y, et al. Medical aspects of ketone body metabolism. Clin Invest Med. 1995;18(3):193-216.