Sorry, I don't understand Jay's cited article. It looks like the nice fluffy LDL particles (which you want) decrease in the absence of fats and on a lower fat diet you get more of the smaller particles which are the dangerous ones. Could someone set me straight if I am wrong.
That citation was not on point and I should not have used it, as I said above.
The question you asked was about LDL particle size and how to change the ratio of A/B. The main factors for this specific question have to do more with reducing the triglyceride from sugar and refined carbs than fat consumption.
That cited study only looked at just changing the amount of fat consumed, leaving other factor the same in total calories. But what the study appear to have done was substituent the higher fat calories with refined carb calories by 20%. Raising your intake of refined carb (sugar, corn syrup, etc) will RAISE triglycerides and inversely and negatively effect the A/B ratio.
So the point of this limited study is that decreasing fat intake from 46% to 24% and substituting the lost calories with sugar will raise the bad LDL A/B ratio.
However, in this WOE neither is recommended because the best answer and results are to eliminate both fat and processed food. When your LDL becomes low enough the A/B ratio is not as significant, if at all, a risk factor for CVD.
I hope this addresses your question.