Dietary guidelines promoting low-fat foods is perhaps the biggest mistake in modern medical history, resulting in devastating consequences for public health. Sadly this unhelpful advice continues to be perpetuated. The current Eatwell guide from Public Health England is in my view more like a metabolic timebomb than a dietary pattern conducive for good health. The scientific integrity of the PHE advice had been compromised by commercial interests. We must urgently change the message to the public to reverse obesity and Type 2 diabetes. Eat fat to get slim. Don’t fear fat; fat is your friend.