Is the keto diet really a healthy plan to lose weight?

Celebrities praise it but is the high-fat, low-carb keto diet really as effective for weight loss as they claim? Here’s what you need to know.

Even if you haven’t tried it, chances are you know someone who swears by keto.

Enthusiasts trumpet the high-profile diet as a miracle, no-hunger weight-loss regimen with a host of health benefits.

But is it the right weight-loss program for you?

Here is what you need to know about the keto diet.

On this page:

• What is the keto diet?
• How does the keto diet work?
• What foods can you eat on the keto diet?
• What foods can’t you eat on the keto diet?
• What does a keto breakfast look like?
• What are the benefits of a keto diet?
• Is the keto diet healthy?
• Are there any cons to going keto?
• What are the side effects of being on a keto diet?

What is the keto diet?

Once used as a treatment for epilepsy in children, the ketogenic diet now revolves around weight loss.

Famously followed by actresses such as Halle Berry and Megan Fox, this diet more or less inverts the food pyramid, strictly limiting carbohydrates to about 20g to 50g a day to focus on fat and protein consumption.

The difference between keto and other low-carb diets, such as Atkins and paleo, is that it restricts carbohydrate intake much more severely, Dietitians Australia dietitian Milly Smith explains.

“This can make it tougher to stick to long-term,” Milly says.

How does the keto diet work?

Following a keto diet forces the body to burn fat as its main source of fuel, breaking it down into ketones through a process called ketosis — which is where the diet gets its name from.

“Typically, this leads to rapid weight loss; however, this is predominantly due to water loss, and because a diet high in protein and fat causes you to be less hungry,” Milly says.

University of Newcastle nutrition and dietetics Professor Clare Collins says between consuming high-fat foods and restricting carbohydrate intake, keto diet followers eat less, which could ultimately lead to weight loss.

“There’s nothing magical about it,” Prof Collins says.

“Your daily carbohydrate intake might be as little as a slice of bread; and the high amount of fat can lead to feeling slightly nauseous, so you don’t eat as much.

“While this (fat) isn’t our preferred fuel, our body and brain are clever and can run on ketones — but with side effects.”

What foods can you eat on the keto diet?

On a ketogenic diet, 70 to 80 per cent of your total daily calories come from fat, 10 to 20 per cent from protein, and no more than 10 per cent from carbohydrates.

“The main foods consumed in a keto diet include meat, fish, eggs, cheese, oils and cream,” Milly says.

“It can also include avocado, nuts and low-starchy vegetables.”

Healthy keto-friendly recipes to try at home:

• Zoe Bingley-Pullin: Banana leaf steamed snapper with zesty broccolini
• Greens with avo and goat’s cheese
• One pan crispy chicken with caramelised onions and lemon
• Carb-free cloud bread burgers

What foods can’t you eat on the keto diet?

With a limit of 20g to 50g of carbs a day — the equivalent of half a bun — there’s a list of foods to avoid.

“On a typical keto diet, carbohydrate foods are restricted which includes rice, pasta, bread, wholegrains, legumes or pulses, fruit and starchy vegetables like potato, sweet potato and corn,” Milly says.

“This also includes restricting foods high in added sugar and many more highly processed foods such as chips, chocolate, lollies and many takeaway foods.”

What does a keto breakfast look like?

Milly says the first keto meal of the day typically includes some protein and low-starchy vegetables — such as an omelette or scrambled eggs, topped with avocado, spinach or tomato.

Keto breakfast ideas to try at home:

• Keto omelette with mushrooms and feta
• Mexican breakfast salad with chilli eggs
• Gorgeous green omelette with macadamia ricotta
• Chilli avocado scrambled eggs

What are the benefits of a keto diet?

Studies have shown the keto diet to be effective for rapid short-term weight loss.

Clinical trials have also demonstrated carbohydrate restriction could be beneficial for hyperglycaemia and Type 2 diabetes, and one study shows it may improve cognitive performance in Alzheimer’s patients.

“This diet does promote a higher intake of lean proteins and vegetables than many Australians currently consume, and excludes processed sugary foods we shouldn’t eat much of,” Milly says.

Is the keto diet healthy?

“Healthy aspects of the keto diet include its reduction in highly processed foods and takeaway, which often hold little nutritional value,” Milly says.

A 2019 study shows ultra-processed foods make up nearly half of the Australian diet, contributing 42 per cent of energy intake.

The keto diet also encourages increased intake of low-starchy vegetables, which most Australians are not consuming enough of, Milly adds.

Are there any cons to going keto?

“A high-meat, low-fibre diet reduces gut microbiota, and too much meat carries with it a risk of bowel cancer,” dietitian Joanna Baker, of Everyday Nutrition, says.

“Restrictive diets are difficult to maintain, lead to bingeing and interfere with a person’s relationship with food.”

Studies show there are other risks, including dehydration, constipation, low protein in the blood, extra fat in the liver, kidney stones, and micronutrient deficiencies.

Because the diet does not differentiate between saturated and unsaturated fats, Milly adds there may be an associated increased risk of heart disease if foods high in unhealthy fats are consumed, such as cream, butter, sour cream and cheese.

“The key to healthy, long-term weight loss is to find an eating pattern that is sustainable for you over time,” Milly says.

“The broad reduction in healthy carbohydrates not only makes the (keto) diet more unsustainable, it also limits important sources of dietary fibre and other key nutrients for our body.”

What are the side effects of being on a keto diet?

Producing ketones can lead to bad breath and people may experience headaches and fatigue and be at risk of dehydration.

“Your body mobilises fat out of the liver and that can stir up inflammation and perhaps fatty liver disease or gallbladder disease,” Prof Collins says.

Limited vegetables and reduced carbohydrate consumption may also mean low fibre intake, so constipation is a risk.

The diet can also be low in nutrients such as folate, magnesium and iodine – all important for overall health.

“If you want to lose weight rapidly in the short term, removing foods and drinks that contain highly processed carbohydrates is recommended,” Prof Collins advises.

“That will lower your total carbohydrate intake.

“The classical ketogenic diet is not a recommended strategy for weight loss.”

More on diets, plus helpful dietary advice:

• What experts say about the carnivore diet
• Heard of the liver cleansing diet? Here’s what you need to know
• What is the SIBO diet and how does it work?
• How to get off the glucose rollercoaster and find sweet balance

 Originally written by Dimity Barber, September 2022. Updated by Melissa Hong, April 2024.