High-fat, low-carbohydrate diets have been shown to raise plasma cholesterol levels, an effect associated with the formation of large low-density lipoprotein (LDL) particles. However, the impact of dietary intervention on time-course changes in LDL particle size has not been investigated. To test whether a short-term dietary intervention affects LDL particle size, we conducted a randomized, double-blind, crossover study using an intensive dietary modification in 12 nonobese healthy men with normal plasma lipid profile. Participants were subjected to 2 isocaloric 3-day diets: high-fat diet (37% energy from fat and 50% from carbohydrates) and low-fat diet (25% energy from fat and 62% from carbohydrates). Plasma lipid levels and LDL particle size were assessed on fasting blood samples after 3 days of feeding on each diet. The LDL particles were characterized by polyacrylamide gradient gel electrophoresis. Compared with the low-fat diet, plasma cholesterol, LDL cholesterol, and high-density lipoprotein cholesterol were significantly increased (4.45 vs 4.78 mmol/L, P = .04; 2.48 vs 2.90 mmol/L, P = .005; and 1.29 vs 1.41 mmol/L, P = .005, respectively) following the 3-day high-fat diet. Plasma triglycerides and fasting apolipoprotein B-48 levels were significantly decreased after the high-fat diet compared with the low-fat diet (1.48 vs 1.01 mmol/L, P = .0003 and 9.6 vs 5.5 mg/L, P = .008, respectively). The high-fat diet was also associated with a significant increase in LDL particle size (255.0 vs 255.9 Å; P = .01) and a significant decrease in the proportion of small LDL particle (<255.0 Å) (50.7% vs 44.6%, P = .01). As compared with a low-fat diet, the cholesterol-raising effect of a high-fat diet is associated with the formation of large LDL particles after only 3 days of feeding.
Taubes' Good Calories Bad Calories paints the picture of small, dense LDL formation, and I've commented on that topic several times over the years. Short version: High carb diets force conversion of high blood sugars to fat/triglycerides, which necessitates the formation of VLDL, which converts to small, dense LDL after the triglycerides are ferried to their destination (fat cells). The small, dense LDL are associated with inflammatory markers and increased "risk" of heart disease, arterial damage, ETC. By contrast, large, fluffy LDL are associated with decreased "risk". The "risk" comment is in quotes, because usually this is the language of epidemiology, which is not legitimately used to determine causation.
Why do you care that low carb diets can reduce your levels of small dense LDL in just three days time? Short version: because small, dense LDL are part of a fasting lipid profile that almost everyone agrees is an indication of sickness. That profile is low HDL, high triglycerides, high LDL, and likely includes also: high glucose, high A1c, high fasting insulin, low insulin sensitivity, high blood pressure, and most likely excess body fat around the waist/internal organs. This, my friends, is the profile of someone who is sick from eating a neolithic agricultural diet.
So this article is good news, because it indicates you can start the healing in as little as three days.
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