High fat dieting has been demonized to raise cholesterol. However, more research is showing the cardiovascular benefits in low carb high fat diets.
Cholesterol is a class of lipids (or fats) in the body. It is a waxy substance that has a variety of functions such as building hormones (estrogen and testosterone), maintaining the integrity of cell membranes, and aiding in the absorption of vitamins (fat soluble vitamins).
Your body gets all the cholesterol needed through internal production from the liver and various other cells of the body (75%) or from dietary sources (25%) (1).
Cholesterol is transported in the blood by molecules known as lipoproteins which are composed of fat and protein. Most are familiar with them, as they are what is reported for our health measures…. HDL, LDL, etc.
Lipoproteins 101 (Cholesterol)
High Density Lipoproteins (HDL), also referred to as “good cholesterol” have two main functions:
1. Transporting cholesterol around the body
2. Collecting cholesterol that is not being used by cells and brings them back to the liver to be recycled or destroyed.
As a result, HDL prevents clogging and accumulation of cholesterol in the arteries.
Low-density lipoprotein (LDL) also transports cholesterol produced by the liver and cells throughout the body; however, LDL molecules move slower and are vulnerable to being oxidized. When they are oxidized, these molecules can impede cardiovascular function by burrowing into the walls of the arteries. Thus, they get a bad rap and are often referred to as “bad cholesterol”.
Even more damaging can be lipoproteins called very low density lipoproteins (VLDL). These particles transport triglycerides in the body, and are more likely than other lipoproteins to clog vessels and impair cardiovascular functions.
What is The Impact of a Ketogenic Diet on Lipoprotein Levels?
Research suggests that a low-carb, high-fat ketogenic diet may have a clinically-positive impact on each form of lipoprotein.
In general, a lower carb approach has been shown to be more advantageous for HDL cholesterol, with about 12% greater amounts of HDL being found in subjects with the lowest carbohydrate intakes (2).
The same findings have been discovered in other studies, where low carb dieting (<50 grams) was associated with double the increase in HDL concentrations versus a low-fat approach (3). Even better, a more stringent approach (<20 grams) resulted in increased almost four times as much as that found in the low-fat diet (4).
In regards to LDL and VLDL, a 12-week diet intervention containing 10% of energy from carbohydrates (<50 grams) decreased the number of LDL particles by 9.6%, increased the size of those particles by 5.2%, and decreased the number of VLDL molecules by 19% (5).
In addition, another 6-month ketogenic intervention resulted in decreases of 11% in LDL particle concentration, with the average particle size being increased by 2% (6). This optimization in LDL cholesterol was less pronounced in the low fat group compared to the low-carb ketogenic diet group. This is key to understand as most doctors now understand that LDL may not be the biggest culprit, but rather it is the VLDL that is associated with the most issues. By increasing the particle size of VLDL, they are less likely to become “clogged” and potentially have less issues long term.
There is some research out there suggesting that a ketogenic diet can lead to an increase in LDL cholesterol; however, this is typically a misinterpretation of the increase in LDL particle size that we previously discussed. Additionally, it is thought that this increase may occur as a result of the increase in HDL cholesterol. Therefore, though total cholesterol may rise, it is the ratio of HDL to LDL that seems to truly matter. Thus, properly constructing a well-formulated ketogenic diet should have beneficial effects long term on cholesterol levels, despite the high fat nature of the diet.
- There is still much confusion and misinterpretation of the data concerning high fat dieting and improved cardiovascular function.
- Improved blood lipid markers can reduce the risk of atherosclerosis, coronary heart disease and other CVDs.
- Ketogenic diets have shown benefit for improving blood lipid markers
- Johnson, T. D. (2010). Mind your cholesterol for a healthy heart. The Nation’s Health, 40, 24-24.
- Merchant, A. T., Anand, S. S., Kelemen, L. E., Vuksan, V., Jacobs, R., Davis, B., … & SHARE and SHARE-AP Investigators. (2007). Carbohydrate intake and HDL in a multiethnic population. The American journal of clinical nutrition, 85(1), 225-230.
- Bueno, N. B., de Melo, I. S. V., de Oliveira, S. L., & da Rocha Ataide, T. (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 110(07), 1178-1187.
- Brinkworth, G. D., Noakes, M., Buckley, J. D., Keogh, J. B., & Clifton, P. M. (2009). Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo. The American journal of clinical nutrition, 90(1), 23-32.
- Wood, R. J., Volek, J. S., Liu, Y., Shachter, N. S., Contois, J. H., & Fernandez, M. L. (2006). Carbohydrate restriction alters lipoprotein metabolism by modifying VLDL, LDL, and HDL subfraction distribution and size in overweight men. The Journal of nutrition, 136(2), 384-389.
- Westman, E. C., Yancy, W. S., Olsen, M. K., Dudley, T., & Guyton, J. R. (2006). Effect of a low-carbohydrate, ketogenic diet program compared to a low-fat diet on fasting lipoprotein subclasses. International journal of cardiology, 110(2), 212-216.