Why a ketogenic diet is NOT the answer.

*Article written by SBF dietician Peita HYNES BAppSc (HMS) hons. BHlth Sc (Nutr & Diet) hons. 

A ketogenic diet is really just another fancy word for a very low carbohydrate diet. The idea is to put your body into a state called ‘ketosis’.

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What is ketosis? Firstly we need to go through a bit of physiology…

  • Your body utilises carbohydrate and fat as its main fuel supply.
  • Protein is only used when the body is depleted of carbohydrate and fat as a fuel source.
  • Our primary form of fuel is glucose, the simplest form of carbohydrate.
  • All carbohydrate foods (whether it be sweet potato or jelly beans) will eventually break down to form glucose in our bloodstream.
  • Glucose is then used by our muscles, not just skeletal muscles but also our heart, lungs and other organs as fuel to function.
  • It is essential for your brain as it is the only macronutrient that can cross the blood brain barrier, i.e. your brain cannot function off fat or protein as a fuel source. (This is why if you’re on a low carb diet, you’ll find yourself a bit fuzzy).
  • Fat from foods breaks down to form ‘fatty acids’ and also is used as a fuel for our body. We’re usually using a combination of glucose and fat to fuel us during the day.
  • Glucose is your body’s preferred fuel source when you are exercising at high intensities. This is why carbohydrate is important for elite athletes to perform at their best.
  • Fat is the favoured fuel source in lower intensity exercise or at rest and why if you’re not doing high intensity exercise, you can afford to cut your carbohydrate foods down (but not out!).

Glucose or carbohydrates are important to keep our body functioning optimally. BUT obviously it is important to eat wholesome carbohydrate foods (such as whole grains, legumes, lentils and starchy vegetables) and in the right amounts.

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KETOSIS is a metabolic process in your body when you are not eating enough carbohydrate foods to fuel your body. Your body only has limited stores of carbohydrate in your muscles and liver (around 500g) compared to fat stores which, depending on the person, are usually at least 10kg or more if you’re very overweight. If you start eating a very low carbohydrate diet (which can be anywhere from 20-100g of total carbohydrates per day), your body firstly uses all its stores of carbohydrate and then starts converting fatty acids into ketones. These ketones can also cross the blood brain barrier and are then used in your body as energy in place of the glucose. This process is called ketosis.

Ketosis will see dramatic weight loss effects as you’re eating in an energy deficit and using your stored fat as an energy source HOWEVER:

It is not healthy to have excess ketones in your body for long periods of time.

A ketosis diet is usually a diet that needs strict medical monitoring and used only for particular health conditions such as epilepsy. It’s also used for morbidly obese patients before bariatric surgery to reduce the size of their liver and prevent complications with surgery.

It will initially help you lose weight BUT it is not a long term approach to weight loss. Quick weight loss on an unsustainable meal plan ONLY leads to a long term higher weight! Healthy eating is about eating all foods in moderation and the majority of your diet should consist of whole grains, legumes, lentils, vegetables, lean meats/fish/chicken, nuts, seeds, fruit and dairy. What’s the point in following a diet and losing 20kg to put back on 30kg in 6 months?

Carbohydrate is essential for fibre, B vitamins and adding bulk to prevent bowel conditions and constipation.

The safest, healthiest, long term solution to weight loss is a balanced diet (which includes carbohydrates) in recommended portion sizes. A single serve for foods like rice and pasta is quite small (½ cup cooked rice or pasta) and often people will exceed the recommended daily amounts!Kay - Testimonial for SBF Challenge 

Our SBF Challenge fuel plans follow specific recommendations for all macronutrients. They’re created with the intention of you eating these foods LONG TERM. Simple, healthy recipes and guidelines that will change your lifestyle and change your body without resorting to drastic “quick fix” diets.

If you’d like to join our team, as a VIP member please register here:


There are obviously specific medical conditions where it is important to limit carbohydrate intake. If you would like further information about carbohydrate intake specific for you, seek advice from a accredited practicing dietitian.

*Article written by SBF dietician Peita HYNES BAppSc (HMS) hons. BHlth Sc (Nutr & Diet) hons. 

Author: Sally Brouwer

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