Today’s guest post is part of an editorial collaboration with the folks at HVMN who are experts on ketones and the ketogenic diet. Note: This is NOT a sponsored post.
A balanced macronutrient intake is essential for success on the keto diet. Macronutrients are food groups humans consume in large quantities. They provide the bulk of the energy to the body.
The primary macronutrients are carbohydrates, fats, and proteins.
Some examples macronutrients based on foods you might eat every day. Carbohydrates: bread, pasta, potatoes, cereals, sugary food (sweets). Fat: oils (olive oil, coconut oil), butter, fatty cuts of meat, brazil nuts, macadamia nuts, avocado. Protein: beef, chicken, pork, fish, milk, cheese, yoghurt, eggs.
The main function of dietary carbohydrates is to be a source of energy. Some say that dietary carbohydrates are not essential, as they can be made from dietary protein and fat.
Carbohydrates are biological molecules that contain carbon, hydrogen, and oxygen, usually with a 2:1 ratio of hydrogen:oxygen. Carbohydrates occur as a collection of single units (monosaccharides, e.g. glucose), two molecules joined (disaccharides, e.g. sucrose), and chains of molecules (oligosaccharides and polysaccharides).
When following a ketogenic diet, carb intake should be very low.
This contrasts with the modern diet, which is high-carb: most dietary calories come from carbohydrates (and often, processed foods). Consuming carbohydrates causes insulin release (leading to higher insulin levels), which inhibits ketone production in the liver and thus ketosis. Therefore, monitoring and modulating your carbohydrate intake is an important part of following the ketogenic diet.
When you’re following the ketogenic diet, key concepts are the total amount of carbohydrates, the net amount of carbohydrates (accounting for the accompanying fiber), and the speed with which carbohydrates raise blood glucose (glycemic index). With a standard ketogenic diet, it’s recommended to keep the total amount of carbohydrates limited to less than 5% of energy intake.
Dietary fibre is carbohydrate-based material from plants that is not entirely broken down by the small intestine. Instead, it passes to the large intestine, and either undergoes fermentation (which supports the growth of beneficial bacteria), or excretion.
Fibre is a significant part of a well-formulated ketogenic diet. It helps to maintain gut health, and also increases food bulk and helps with the feeling of fullness. Green and cruciferous vegetables are rich in fibre and are helpful to include in a ketogenic diet.
Net carbs refer to the mass of total carbohydrates, minus the total fibre, which could be a better metric to judge carbohydrate intake because:
- Fiber is mostly digestion-resistant and so should not increase blood glucose
- Studies have shown an increase in fibre does not affect blood ketone levels
The ‘glycemic index’ is a scale that ranges between 1 and 100, and it indicates how quickly food raises blood glucose after consumption. Pure glucose is the reference and is set at 100 (meaning, raises blood glucose quickly). Other foods have a comparatively lower value as they raise blood glucose more slowly. Example values for the glycemic index of food are white potato (~80), white bread (~75), apple (~35) and peanuts (~15).
Proteins are large molecules composed of chains of amino acids. The functions of dietary protein are:
- Building structural and functional components of cells
- Conversion to glucose via gluconeogenesis
- Top up intermediates in other metabolic pathways, such as the Krebs Cycle
When following a ketogenic diet, there must be a balance of sufficient protein to maintain muscle mass. If dietary protein exceeds 20% – 25% of calories, gluconeogenesis from protein can stop ketone production. Initially, target a protein intake of 0.8g – 1.2g per kilogram of body weight. This target balances the need for protein against the chance of excess gluconeogenesis.
Some individuals (such as strength or endurance athletes) may have higher protein requirements. They might require a modified ketogenic macronutrient ratio of 2:1 fat: non-fat (where 65% of energy is fat, 30% is protein, and 5% carbohydrate) and can still be effective for therapeutic ketosis.
Fat gets a bad rap. In nutrition, fat is the dietary macronutrient made up of triglyceride molecules. The main functions of fats in the diet are to provide increased energy levels and make up key functional and structural parts of the human system.
But we often misuse the word “fat”. There’s a difference between fat in cells and different types of fat molecules:
- Adipose tissue: the tissue that stores energy as fats/lipid droplets inside adipocytes (fat cells). This is body fat.
- Adipocytes: individual cells that store fats/lipids
- Lipids: the most general term for insoluble and polar biological fat molecules. The lipid class of molecules includes mono-, di- and triglycerols, cholesterols, and phospholipids
- Triglycerides: a lipid molecule made up of glycerol (that acts as a backbone) joined to three fatty acid molecules
- Fatty acids: a molecule composed of a chain of carbon atoms bonded to one another with a carboxylic acid at one end
Lipids are digested and travel in the blood as triglycerides and fatty acids before being used as a fuel, or stored by adipocytes in adipose tissue. Dietary lipids undergo many tightly regulated metabolic steps before storage in adipose tissue. Dietary fat does not equal stored body fat.
Triglycerides are the most important source of energy in a ketogenic diet. They account for > 70% of dietary calories. For those following a ketogenic diet, it’s helpful to understand how the lipid source in the diet is processed in the body.
Fatty acids can be saturated (no double bonds between carbons), or unsaturated (one or more double bonds between carbons).
Saturated fats are relatively stable and tend to be solid at room temperature (i.e. lard, butter, coconut oil). Historical guidelines recommended limited the intake of dietary saturated fats because fat consumption was thought to be associated with heart disease and high blood pressure. However, emerging research has shown saturated fat can have beneficial effects on blood biomarkers (i.e. increase healthy HDL cholesterol levels).
Unsaturated fatty acids can be further divided into monounsaturated fats (only one double bond between carbons) and polyunsaturated fats (multiple double bonds between carbons). The number of double bonds is important as it determines how the fatty acid behaves both inside and outside of the body.
They tend to be liquid at room temperature (i.e. vegetable-based fats such as olive oil). Unsaturated fats are thought of as healthier than saturated fats (also known as “healthy fats”). Increased consumption of mono- and polyunsaturated fats have been linked to improved blood biomarkers (i.e. lower blood triglycerides). Eating enough unsaturated fats is important when following a ketogenic diet.
Increased fat consumption is not associated with cardiovascular disease.1
Eating a moderate amount of saturated fat is unlikely to be as harmful as previously believed, and saturated fat consumption as part of a ketogenic diet is unlikely to increase the risk of cardiovascular disease.
Trans-fats are produced artificially when hydrogen is added to unsaturated fatty acids in order to solidify it and make it last longer. Avoid high levels of trans-fat consumption by eating a diet based around whole foods.
Essential fatty acids are important to include in the diet because the body cannot naturally produce them. This group includes poly-unsaturated Omega 3, Omega 6, and Omega 9 fatty acids.
It’s believed the anti-inflammatory effects of essential fatty acids may have broad benefits for health and performance. Oily fish, such as sardines and mackerel, and seeds (i.e. flax) are good dietary sources of essential fatty acids. If you don’t get enough of these in your diet you can take a supplement that includes fish oil.
When integrating these concepts into a ketogenic diet: target the majority of dietary calories as fat. Aim to include a variety of fats from different animal and plant sources (i.e. red meat, poultry, fish, dairy, olive oil, coconut oil, nuts, and avocados).
Micronutrients on a Keto Diet
Conversely to macronutrients, micronutrients must be obtained in the diet in small quantities, but are essential to health. Vitamins and minerals are examples of micronutrients.
When following a ketogenic diet, it is important to be mindful of micronutrient intake because:
- Reducing carbohydrate intake can lower consumption of micronutrient-rich foods (i.e. fruits and vegetables)
- In the initial 28 days of following a ketogenic diet, the balance of some micronutrients (such as sodium, potassium, magnesium, and calcium) can become disturbed due to an increase in their excretion. The body resolves this issue naturally after adapting to the diet
Sodium is the principal cation in extracellular fluid. Its functions are related to blood volume maintenance, water balance, and cell membrane potential. Sodium is also essential for acid-base balance and nerve conduction.
The level of sodium can fall at the start of a ketogenic diet.
Adding extra sodium to meals (like adding salt or consuming bone broth) can reduce the chances of feeling the common side effects associated with low sodium (like cramps).
Potassium is the principal cation in the intracellular fluid. Its primary functions are related to maintaining cell membrane potential and electrical activity in cells such as neurons and cardiomyocytes. As with sodium, levels of potassium fall at the initiation of a ketogenic diet due to increased excretion.
When starting a ketogenic diet, include sources of potassium like nuts, dark green vegetables, and avocados.
Magnesium is an essential element in biological systems, especially for nerve, muscle, and immune function. Levels of magnesium also fall at the initiation of a ketogenic diet due to increased excretion.
When starting a ketogenic diet, include sources of magnesium like oily fish, dark green vegetables, and seeds.
Calcium has a role in muscle contraction and is important for cardiovascular and bone health. Calcium deficiency is less common during a ketogenic diet, as staples of the diet such as fish, cheese, and leafy greens are rich sources of the mineral.