Food & Nutrition

What is the keto diet and how does it work?

An easy-to-understand guide to one of the trendiest diets of the last few years.
Published 22 April 2019

Keto diet overview

It seems like no matter where you turn; someone is talking about, blogging about, or ‘gramming about keto and its rapid effects on weight loss and its health benefits. In fact, keto recipes were the number one searched recipe term in 2018. So, what is all the hype really about?

Keto is the common term for what is more formally called the ketogenic diet; essentially an ultra low carbohydrate diet. The basics of the ketogenic diet are high fat, moderate protein, and very little carbohydrates. The typical ratio is 70-80 per cent fat; about 10-20 per cent protein; and about 5-10 per cent carbohydrates.

The initial weight loss is attributed mostly to water loss from the acute, dramatic reduction of carbohydrates. When you eliminate nearly an entire category of foods (in this case, carbohydrates) you are left with far fewer foods to eat and will therefore likely be eating less.

Second to consuming less, when you get most of your kilojoules from fat, it forces your body into a state called ketosis, whereby your body derives its energy from ketones instead of glucose.

What is ketosis?

To understand ketosis, it’s helpful to know a bit about how your body uses energy from the foods you eat.

The cells in your body prefer to use glucose (sugars from the carbohydrates you eat) as a source of energy. When you dramatically reduce the number of carbohydrates you consume and replace them with fats your body goes into a state of ketosis. This means the liver begins producing ketone bodies from stored fats that will be used as a source of energy in the absence of glucose, thereby burning fat instead of carbohydrates.

Whether you are eating a high or low carbohydrate diet, you are only going to lose weight when you consume fewer kilojoules than your body burns.

Does the keto diet work?

Remember how we talked about the body preferring glucose from carbohydrates as a source of energy? Well, the body stores a small amount of this glucose in the form of glycogen. When you start going keto, your body uses up what little stores of glycogen it has and sheds that with water. Note that once you increase your consumption of carbohydrates again, the effects are reversed.

What are the benefits of keto diet?

The theory is that if you deprive your body of its main source of energy (glucose from carbohydrate-containing foods), it goes into a state of ketosis, where it burns fat stored in the body for fuel, instead. During this process, by-products called ketones are produced, which are then used by the body's muscles, tissues, and brain.

The science shows that a ketogenic diet may benefit people living with specific health concerns, including epilepsy, some types of cancer and even dementia. Some studies have shown it can also result in short-term weight loss, as well as delivering positive impacts on blood pressure, cholesterol levels, and blood sugar. But not only did a review study published in 2013 find that after a year, these effects weren't significantly different to those achieved via conventional weight-loss methods, research has also shown that dropout rates are high among people following a keto diet because it's restrictive.

What do you eat on keto?

Fats, proteins, and minimal carbohydrates are what you need to eat to be successful on keto. Carbohydrates will make up a significantly smaller portion of your diet on keto than on an average eating plan. On keto, you would have to eliminate most carbohydrates, including obvious sources like bread and pasta, and less obvious sources, like fruits and veggies.

Keto approved foods

Fats: 70-80%Protein: 10-20% Carbohydrates: 5-10%

Oils – coconut, olive, etc.
Animal fats – duck fat, lard, tallow, etc.
Pork rinds

Organ meats
High-fat dairy
Deli meat
Oily fish

Leafy green vegetables (these are the most keto-approved veggies)
Berries and other low-sugar fruits

The keto and carb relationship

To work keto properly, a dramatic decrease in carbohydrates is required. Carbohydrates can be found in a wide variety of foods which you would need to eliminate from your diet, including pasta, bread, oats, potatoes, fruits, and veggies. There are some concerns that cutting some of these foods means missing out on the broader nutrient benefit that comes from these foods and could lead you to become deficient in essential micronutrients.

Check out the chart below for some sources of carbohydrates. There’s not much to eat when the goal for keto is to stay below 30 grams of daily carbohydrates!

FoodGrams of carbohydrates
1 slice wholemeal bread47 grams
½ cup cooked sweet potato37 grams
1 medium banana30 grams
1 cup plain oats28 grams
¾ cup 99% fat free plain yoghurt15 grams
350ml lager beer13 grams
½ cup raw carrots12 grams
1 cup orange juice11 grams
½ cup steamed broccoli11 grams
½ cup cooked cauliflower5 grams

Is keto hard to follow?

Many have found keto a workable diet during a focused period of weight loss. Studies have shown keto can be restrictive and hard to follow over the long term and it can be heavy on red meat and other fatty foods that are increasingly considered to be risk factors for multiple chronic diseases.

Is keto safe?

Following the keto diet means increasing the amounts of fats in your diet. Keto does not differentiate between the quality of fats (saturated vs unsaturated) and only mandates you eat a lot of it. Foods high in saturated fat come with known health risks including increased risk of heart disease.

Keto does not align with the Australian Dietary Guidelines, which emphasises eating plenty of fruits and vegetables, whole grains, and plant-based proteins.

The best eating plans are ones that you can stick with for the long term, include a wide variety of foods, and don’t require you to eat from a list of ‘approved’ foods. Some people have found that keto works well for them, and others have found it can be hard to sustain.

If you have pre-existing liver or kidney conditions, heart disease or diabetes, you should seek the advice of a doctor before undertaking any significant changes to your diet.