Getting Started with Low Carb High Fat

By Jessica Turton & Thomas Paavola

Your body is not a machine; it is a complex system that requires essential nutrients from your diet to survive and thrive. By shifting focus away from Calories and towards nutrient-density, we can change the fuel our body burns and regain control of our health. A low carbohydrate diet is not only about restricting carbohydrates but more importantly, a well formulated low carbohydrate diet should be focused on including more high quality sources of essential proteins, fats, vitamins and minerals.

Fuel Systems of the Body 

Our body has two major fuel systems; glucose and fat. Glucose comes from dietary carbohydrate (starches and sugars) and gluconeogenesis (glucose made by the liver). Glucose is a short-acting fuel with minimal storage capacity in the body. If you choose to use glucose as your primary source of fuel, you need to top-up the tank multiple times each day to maintain good energy (hence the rationale for eating five or more small meals a day to “rev up” the metabolism). Excess glucose is stored as fat.

Fat is our second choice of fuel and comes from dietary fat and stored body fat. Fat is a long-acting fuel with unlimited storage capacity – even a lean person has plenty of stored energy on their body. Using fat as your primary source of fuel allows you to maintain stable mental and physical energy for many hours without having to fill up the tank numerous times every single day – given you can tap into your stored energy supply. Fat is also an anti-inflammatory fuel due to the increased presence of circulating blood ketones (which come from the breakdown of fat). The term nutritional ketosis typically refers to an elevated blood ketone level of 0.5-3.0 mmol/L.

Why Go Low Carb?

Everyone has a different level of carbohydrate tolerance which can be determined by your insulin sensitivity. Insulin is a hormone that is released by the pancreas and allows for excess glucose in the blood to be transported into the cells (e.g., liver cell, fat cell, muscle cell) where it is used for energy or stored as fat. Insulin allows glucose in the blood to return to a safe baseline level (~5 mmol/L) after the ingestion of carbohydrate-based meals. However, there are many factors that can cause our insulin to work less efficiently and insulin resistance can develop. These factors include; genetics, ageing, low muscle mass, stress, and excessive carbohydrate intake. Insulin resistance requires your body to produce larger and larger amounts of insulin to metabolise a given amount of carbohydrate, and return your blood glucose to a safe baseline after meals.

Producing high levels of insulin reduces your ability to access stored energy. Insulin acts as a big padlock on body fat, so when insulin levels are high (from consuming large and frequent amounts of carbohydrate), fat burning is switched off and fat storage is switched on. To provide your body with access to the energy that it has stored away as fat, we must lower the demand for insulin. This can be achieved by lowering dietary carbohydrate intake.

With the consideration that insulin sensitivity is required to efficiently metabolise carbohydrates, insulin resistance and hyperinsulinemia (high insulin levels) can be thought of as issues of carbohydrate intolerance. Symptoms of carbohydrate intolerance may include lethargy and fatigue after eating, excessive hunger, irritability between meals, weight gain, high blood sugar levels and inflammation (including digestive upset and pain).

A low carbohydrate diet allows the body to spend more time using fat for energy, rather than sugar.

On the flip, side, benefits of burning fat for energy (irrespective of your insulin sensitivity) include:

  • Better energy levels, mental clarity and low appetite
  • Weight loss and improved body composition
  • Improved cholesterol profile (lower triglycerides and increased HDL)
  • Lower levels of inflammation
  • Reduced requirement for insulin
  • Reduced frequency and severity of hyper and hypoglycaemia
  • Improved blood pressure regulation
  • Reduced reliance on medications

What Foods Contain Carbohydrates?

Carbohydrates are abundant in our food supply. Foods such as bread, pizza, pasta, rice, muffins, cereals, grains and crackers, tend to be the most well-known for their carbohydrate density (the amount of carbohydrate per 100 grams). We commonly refer to foods with a high-density of carbohydrate content as “carbohydrate foods”.

Carbohydrate foods can be separated into two categories:

  • Starchy vegetables including potato, sweet potato, corn, taro and yam.
  • Foods made from grains, such as wheat, barley, rice, oats and quinoa, including flour, bread, pasta and cereals.

  • All fruits contain a unique type of carbohydrate called fructose. Lower fructose fruits include berries, while higher fructose fruits include mangos, apples and bananas.
  • Dairy foods contain carbohydrate in the form of lactose. Lower lactose dairy includes cheese and natural yoghurt, while higher lactose dairy includes milk and flavoured or sweetened yoghurts.
  • ‘Added sugar’ which is sugar added to processed and packaged foods.

Reading food labels is the best way to determine the amount of carbohydrate in foods. Using the ‘total carbohydrate content per 100 g’ value is an effective way to calculate the percent of carbohydrate in a given food. A carbohydrate percentage can be useful when comparing products, and can help you to select the product with a lower density of carbohydrate. Keep in mind that food products marketed as “low fat” tend to be proportionally high in carbohydrates as a result (less fat per 100 g generally equals more carbohydrate per 100 g).  When your goal is to burn fat as a primary source of fuel, your intake of dietary fat should increase and there is no need to seek “low fat” products.

Different Types of Low Carb Diets

A low carbohydrate diet is generally defined as anything less than 26% total energy intake from carbohydrate (or less than 130 g per day). Within this range, there are different types of low-carbohydrate diets. We refer to the following categories:

  • Low carbohydrate diet = 50-130 g/day
  • Very low carbohydrate diet = 0-50 g/day
  • Low carbohydrate ketogenic diet = any low carbohydrate diet that causes the body to be in a state of nutritional ketosis (elevated blood ketone levels). The level of carbohydrate at which this is achieved is highly individual, but most people will be in nutritional ketosis when carbohydrates are <20 g/day.

A Day of Eating on a Low Carb Diet

  Day A Day B
Breakfast “DIY Muesli” ½ cup full fat natural yoghurt 2 tbs coconut cream handful of macadamia nuts handful of walnuts handful of raspberries “Bacon & Egg Rolls” 1 whole egg 1 rashers of bacon ½ avocado Tarn’s Keto cheesy bagels (low carb replacement for bread roll)
Lunch Tarn’s Keto Beef Stir Fry Nothing (fast*)  
Snack Tarn’s Keto tomato and mushroom scroll   “Coffee & Cake” Long black 1 tbs of cream or coconut cream Tarn’s Keto cinnamon scroll
Dinner “Taco Night” 100-150 g chicken mince handful of shredded cheese 2 tbs guacamole (mashed avo) 1 tbs sour cream tomato salsa iceberg lettuce leaves (replacement for taco/burrito) “Steak & Bake” 100-150 g steak 1 tbs olive oil Tarn’s broccoli and cauliflower bake 
Dessert peppermint tea handful of strawberries

*It is important to listen to your body. If you are not truly hungry for a meal, you may not need to eat. Alternatively, if your hunger levels are high because you are stressed or have a high activity level, you may need to eat more.

Personalised Nutrition

It is important to understand that we each have our own unique nutritional requirements and one person’s low-carbohydrate diet will and should look different to another person’s low carb diet. You may benefit from working with a proficient health professional who can help you develop a personally-tailored nutrition plan.

By Jessica Turton & Thomas Paavola

Accredited Practising Dietitians, Ellipse Health

About the Authors

Jessica Turton -Jessica is interested in developing, evaluating and improving dietetic strategies for the management of diabetes and is currently undertaking her Research Doctorate (Ph.D) at the University of Sydney under the supervision of A/Prof Kieron Rooney and Prof Grant Brinkworth (CSIRO). Jessica has given talks for Low Carb Down Under which are available on YouTube and she has featured on popular Podcasts including Keto Connect, 2 Keto Dudes, Keto Woman, and Low Carb Conversations. Jessica is a co-developer of the Food Freedom program which is a fully automated online program available at Ellipse Health to help individuals address their physiology to build a healthy relationship with food. 

Thomas Paavola – Thomas is particularly interested in the application of evidence-based dietetic strategies for improving chronic pain management and inflammatory conditions. As a migraine sufferer himself, Tom is extremely compassionate when it comes to addressing complex chronic pain issues and understands the daily challenges involved in living with chronic pain. With a targeted nutritional approach, Tom has significantly reduced his own migraine frequency and enjoys a much better quality of life. This personal experience has fuelled Tom’s passion to empower others with nutritional knowledge and strategies to improve their own health and wellbeing. Tom currently provides in-house dietetic services at the Centre for Gastrointestinal Health and telehealth services (phone or video) with Ellipse Health.