Billy wrote:

At least Atkins has data.

Had data. In the 1970s he tried to have it published but was refused.
Medical journals did not want his tabular data. He stopped mentioning
that he kept tabular data after that. None was ever published.

What he has are studies that support the beneficial effect of several
variations of low carbing. These studies are based on data from the
scientists conducting those studies. Indirect data then.

Folks complain that Dr A's approach was not scientific. I remember him
staying that he wasn't himself a scientist. He was a clinician who used
the studies produced by scientists. The end result was an effective
system no matter that he wasn't a scientist.