A UK report saying saturated fat doesn't cause heart disease and people should eat more of it has been criticised by experts.
Advice to eat more fat to reverse obesity and type 2 diabetes has been strongly challenged by Australia's dieticians.
In a report calling for an urgent overhaul of dietary guidelines, two UK-based charities say the promotion of low-fat foods has had "disastrous health consequences".
Eat Fat, Cut the Carbs and Avoid Snacking, by the National Obesity Forum and Public Health Collaboration, calls for an urgent overhaul of current dietary guidelines.
The authors cite a number of studies, before concluding that a low-carbohydrate, high-fat diet of real foods is an "acceptable, effective and safe approach" to weight loss and health
They say eating fat does not make you fat, saturated fat doesn't cause heart disease and that full fat dairy is likely protective, and processed foods labelled low-fat, lite, low cholesterol or proven to lower cholesterol should be avoided.
"Eat fat to get slim, don't fear fat, fat is your friend," says consultant cardiologist Dr Aseem Malhotra, advisor to the forum.
The Dietitians Association of Australia (DAA), which has 5900 members, defended the Australian Dietary Guidelines - similar to those in other countries - saying they were evidence-based and provide a framework for healthy eating.
"A diet high in saturated fat is a risk factor for heart disease, one of our nation's biggest killers," the DAA said in a statement.
"Saturated fats tend to increase LDL (unhealthy) cholesterol in the blood and current evidence suggests these should be eaten sparingly to minimise the risk of heart disease.
"Instead, foods that are rich in unsaturated fats (such as monounsaturated and polyunsaturated fats) are recommended."
In relation to carbohydrates, choices such as wholegrains and legumes can be part of a healthy diet, and are recommended to help meet daily fibre targets.
Overseas experts also criticised the report saying it was misleading, did not go through scientific peer review and was largely based on selective quotations from the literature.
Public Health England's chief nutritionist Dr Alison Tedstone said the call to eat more fat was irresponsible and potentially deadly.