LDL, HDL and the Boogeyman

"The researchers whose names are listed at the top of this paper are all affiliated with prestigious institutions.  I am quite sure that there is not a single one of them who is unfamiliar with the work over the last 15 years or so of Ronald Krauss, the researcher who made the discovery of the differences between LDL particle sizes. (The same Krauss, by the way, who published the paper about the meta-analysis of saturated fat and heart disease much in the blogosphere currently.) Krauss and his team showed that large, fluffy LDL particles aren’t particularly harmful whereas the small, dense LDL particles are the ones that cause the problems.  He also discovered that increasing carbohydrate in the diet caused LDL to shift to a smaller, denser pattern while decreasing carb and adding fat made LDL change to the larger, fluffier non-problematic kind.  (You can read a nice review of LDL particle size in this article published in the popular press.)

If you reduce carbs and add fat to the diet, not only does your HDL go up, but your LDL makes a particle size change for the better.  However, when you increase carbs and reduce fat, your HDL goes down and your LDL goes down too, but it changes for the worse. So even though the high-carb, low-fat diet decreases LDL, it doesn’t decrease risk – it increases it because even though LDL is lower, it is made up of a dangerous particle size,which negates any possible value of the fall in LDL.  All of these researchers know this."  http://www.proteinpower.com/drmike/cardiovascular-disease/are-all-diets-the-same/

In other words, with restricted carb intake, you get larger, benign LDL particles, and higher HDL numbers, lower triglyceride numbers, increase your insulin sensitivity, AND will likely lose weight.  You can do this following the Paleo Diet, Atkins Diet, Neanderthin, The Zone, The Protein Power Diet, and probably South Beach, too.  Oh by the way, you'll also sleep better than when on a high carb/low fat diet, your athletic performance will improve, you'll avoid the most likely causes of cancer and the other diseases of the west, you will rarely feel hungry, and your steady blood sugars will keep your brain humming at full tilt all day long.  Post meal crashes will become a thing of the past.

What's the downside of a high fat, restricted carb (50-75g/day of mostly vegetables with some fruit and little starch), moderate protein diet?

I'm not aware of a single downside, unless you can't get over the beer, cake, candy and grains.