The Ketogenic diet - what you need to know about going low carb, high fat
Low carb, high fat, keto and bullet proof coffee are just some 'it' phrases for those following the new diet craze that is taking the wellness industry by storm. The ketogenic diet is fast gaining a cult like following amongst fitness experts, medical professionals and Hollywood stars, looking set to overrule the paleo diet due to its impressive health benefit claims and ability to quickly shed the kilos.
The once popular paleo diet cuts out all grains and legumes and only includes foods that were eaten in caveman days however the high animal protein and saturated fat intake that is promoted in the paleo diet has recently left many health practitioners questioning its long term health benefits.
The ketogenic diet, a somewhat modified Paleo diet, is still high in fats but promotes more of the healthy fats such as nuts, seeds, avocados and oily fish. Protein is included such as lean red meat, eggs, poultry and fish and plenty of low starch plant based foods such as green leafy vegetables.
High starch foods such as rice and potatoes are off the menu due to their high carbohydrate content and effect on blood sugar and insulin spikes. The recommended low carbohydrate intake, moderate protein and consumption of good fats works particularly well for weight loss and fat burning. By dramatically reducing carbohydrate intake to less than 50g a day the body’s instant supply of glucose is removed and this is what we need for energy. Normally the cells of the body use glucose as their primary source of energy. If we are not using carbohydrates for fuel the body has to look for alternate options which means we burn fat by breaking down fat stores to provide glucose from triglycerides. This shifts the body into a state of ketosis meaning the liver produces ketone bodies to use as fuel. This can be beneficial for many including those looking to lose weight.
Many people claim to feel better on a ketogenic diet and the ketogenic diet has been reported to help improve a variety of health conditions including the following –
A standard ketogenic diet generally consists of just 5 per cent carbohydrates, 20 per cent protein and 75 per cent fat, meaning between 10-50g of carbohydrates are consumed each day. Compare this to a recommended healthy diet of 30 per cent complex carbohydrates, 20-30 per cent protein and 20-percent fat.
Some extreme ketogenic diets (which is where the controversy comes in to play) have promoted reducing carbohydrate intake to as low as 5 - 10g a day which means excluding fruits and most vegetables and just eating greens, protein and fats. The long term effects of this type of diet are questionable, highly debatable and potentially dangerous for the majority of the population when followed as a way of life.
Completely cutting out complex carbs such as wholegrains, fruits and vegetables may also diminish important nutrients and fibre in the diet leading to potential nutritional deficiencies and poor gut health. A prolonged state of extreme ketosis i.e. no carbohydrate and high protein intake can mildly increase acid load in the body. In a normal healthy person the body is able to efficiently deal with this posing no dangerous health risk as the blood pH does not change and remains stable. An increased chronic acid load however may lead to potential nutritional deficiencies by leaching alkaline minerals from the bones to compensate for the increased acidity and further accelerate the aging process. This is not to be confused with diabetic ketoacidosis, a condition associated with very high blood glucose levels in type 1 diabetes.
Diabetic Ketoacidosis occurs in type 1 diabetes and is caused by a lack of insulin. Without insulin, our blood sugar levels become high and fat stores are metabolised producing abnormally high levels of ketones. When high blood sugar and ketone levels become high, the acid/base balance in the blood becomes unbalanced and can become dangerous. It is possible for non-diabetics to get ketoacidosis. It can be brought on by alcoholism, starvation and even an overactive thyroid. A well balanced healthy low-carb diet shouldn't cause a problem in healthy individuals.
Possible side effects of extreme (almost no carb) ketogenic diets include –
Lethargy and headaches as the body first adapts
Gut issues – constipation, disruption and starvation of the beneficial gut microbes
Possible thyroid disruption – TSH increase; T3, T4 decrease
Menstrual cycle irregularities due to increased cortisol and decreased progesterone
Mood disorders such as anxiety and depression due to low carbohydrate intake
Glucose & cholesterol issues – whilst the ketogenic diet may prove beneficial for many
with insulin resistance it is possible that the brain may induce insulin resistance to preserve glucose for itself
Pros – An effective diet for weight loss and may be beneficial for those with health conditions such as metabolic syndrome, obesity and insulin resistance. Removing refined carbohydrates and processed foods from the diet promotes a healthier way of eating.
Cons – Long term sustainability is questionable and may put the body at risk of potential nutritional deficiencies, cause gut issues and a decrease in healthy gut flora. To make the diet more of a long term healthier way to eat it is recommended to increase fruit and vegetable content and refrain from any forms of extremism.
There is no one size fits all approach. The same diet does not work for everyone and factors such as general health, size, activity levels, age, genetic variants and medications must all be taken into consideration prior to starting any new diet. Whilst I most certainly recommend cutting out refined carbohydrates and processed foods as recommended in the ketogenic diet there are varying degrees of extremism when it comes to this way of eating. Eating a high plant based diet, high in antioxidants, fibre, good fats and high quality protein is a healthy way to eat. Completely cutting out food groups, following cult like recommendations such as drinking spoonful’s of coconut oil in your morning coffee or eating red meat three times a day with limited vegetable intake is not something I would personally recommend as this may be detrimental to health long term. When undertaking any new diet it is recommended to always seek advice from a qualified accredited nutritionist.
Bravata DM, Sanders L, Huang J, et al. Efficacy and safety of low-carbohydrate diets: a systematic review. JAMA 2003;289:1837-1850
Exton JH, Corbin JG, Harper SC. Control of gluconeogenesis in liver. V. Effects of fasting, diabetes, and glucagon on lactate and endogenous metabolism in the perfused rat liver. J Biol Chem 1972;247:4996-5003
Gutniak M, Grill V, Efendic S. Effect of composition of mixed meals -- low- versus high-carbohydrate content -- on insulin, glucagon, and somatostatin release in healthy humans and in patients with NIDDM. Diabetes Care 1986;9:244-249
CrossRef | Web of Science | Medline
Fukita Y, Gotto AM, Unger RH. Basal and postprotein insulin and glucagon levels during a high and low carbohydrate intake and their relationships to plasma triglycerides. Diabetes 1975;24:552-558
Bisschop PH, De Sain-Van Der Velden MG, Stellaard F, et al. Dietary carbohydrate deprivation increases 24-hour nitrogen excretion without affecting postabsorptive hepatic or whole body protein metabolism in healthy men. J Clin Endocrinol Metab 2003;88:3801-3805
Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J Clin Nutr 2006;83:1055–61. Abstract/FREE Full Text
Murray RK, Granner DK, Mayes PA, Rodwell VW. Harpers illustrated biochemistry. 26th ed. New York, NY: Lange Medical Books/McGraw-Hill, 2003. Google Scholar
Bender, DA. Introduction to nutrition and metabolism. 3rd ed. New York, NY: Taylor & Francis, 2002. Google Scholar