Urging people to follow low-fat diets and to lower their cholesterol is having "disastrous health consequences", a British health charity has warned.
Get the skinny on low-fat diet debate
In a damning report that accuses major public health bodies of colluding with the food industry, the National Obesity Forum and the Public Health Collaboration called for a major overhaul of dietary guidelines.
They say the focus on low-fat diets is failing to address Britain's obesity crisis, while snacking between meals is making people fat.
Instead, they call for a return to whole foods such as meat, fish and dairy, as well as high-fat healthy foods including avocados.
The report - which has caused a huge backlash among the scientific community - also argues that saturated fat does not cause heart disease, while full-fat dairy products such as milk, yoghurt and cheese can actually protect the heart.
Processed foods labelled "low fat", "lite", "low cholesterol" or "proven to lower cholesterol" should be avoided at all costs, while people with Type 2 diabetes should eat a fat-rich diet rather than one based on carbohydrates.
"The most natural and nutritious foods available - meat, fish, eggs, dairy products, nuts, seeds, olive, avocados - all contain saturated fat. The continued demonisation of omnipresent natural fat drives people away from highly nourishing, wholesome and health-promoting foods."
The authors of the report also argue that the science of food has also been "corrupted by commercial influences".
The influence of the food industry represents a "significant threat to public health", they argued.
They said the recent Eatwell Guide from Public Health England was produced with a large number of people from the food and drink industry.
Professor David Haslam, chairman of the National Obesity Forum, said: "As a clinician treating patients all day every day, I quickly realised that guidelines from on high, suggesting high-carbohydrate, low-fat diets were the universal panacea, were deeply flawed.
"Current efforts have failed - the proof being that obesity levels are higher than they have ever been and show no chance of reducing, despite the best efforts of government and scientists."
Dr Aseem Malhotra, consultant cardiologist and founding member of the Public Health Collaboration, a group of medics, said dietary guidelines promoting low-fat foods "is perhaps the biggest mistake in modern medical history, resulting in devastating consequences for public health".
But Professor John Wass, the Royal College of Physicians' special adviser on obesity, said there was good evidence that saturated fat increased cholesterol.
He added: "What is needed is a balanced diet, regular physical activity and a normal healthy weight. To quote selective studies risks misleading the public."
Dr Alison Tedstone, Public Health England chief nutritionist, said: "In the face of all the evidence, calling for people to eat more fat, cut out carbs and ignore calories is irresponsible. Unlike this opinion piece, our independent experts review all the available evidence - often thousands of scientific papers - run full-scale consultations and go to great lengths to ensure no bias."