Back on the menu: Eggs are now celebrated for their protein content while adding butter to potatoes can prevent a spike in blood sugar levels
Milk, cheese, butter, cream - in fact all saturated fats - are bad for you. Or so I believed ever since my days as a medical student nearly 30 years ago.
During that time I assured friends and family that saturated fat would clog their arteries as surely as lard down a drain. So, too, would it make them pile on the pounds.
Recently, however, I have been forced to do a U-turn. It is time to apologise for all that useless advice I've been dishing out about fat.
New studies have not only failed to find a convincing link between saturated fat and heart disease, they have shattered other long-held anti-fat beliefs, too.
We now have compelling evidence that low-fat diets rarely work and that eating the right kind of fat is not only good for your heart but may also help you lose weight.
So why the sudden change? And what is making us fat?
The roots of our current confusion lie in a paper by an American scientist called Ancel Keys in 1953. It covered the increasingly common problem of clogged arteries.
Keys included a simple graph comparing fat consumption and deaths from heart disease in men from six different countries. Americans, who ate a lot of fat, were far more likely to have a heart attack than the Japanese, who ate little fat. Case solved. Or was it?
Other scientists began wondering why Keys chose to focus on just six countries when he had access to data for 22. If places like France and Germany were included the link between heart disease and fat consumption became much weaker.
These were, after all, countries with high fat consumption, but relatively modest rates of heart disease.
In fact, as a renowned British scientist called John Yudkin pointed out, there was actually a much stronger link between sugar consumption and heart disease.