The history of dieting is long and contradictory; one minute we're cutting carbs, the next fat. Is there any merit to these fads or should we avoid them completely?
If you're on any kind of social media you've probably heard of the Keto diet, the latest craze for weight loss. Here is how it works. You dramatically cut back on carbohydrates, including fruit. When your body is deprived of its main source of energy, it turns to fat - specifically your body fat- for fuel.
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Many are evangelical about the weight loss benefits, with others listing side effects like brain fog, keto "flu" and bad breath.
Healthy Food Guide nutritionist Claire Turnbull joined the Project to explain the potential dangers of the diet change.
"When your body is switching over from burning carbohydrates as fuel to burning fat, there are all sorts of symptoms because your physiology is changing," she explained.
"Your gut bacteria [normally] feeds on carbohydrates but because you're burning fat you the gut bacteria die off."
Turnbull says the key is what you replace carbohydrates with.
"Lots of people replace it with bacon and lots of meat and they're not getting even the non-starchy vegetables in," she said.
Watch the full interview to find out more.