The cholesterol theory of cardiovascular disease claims that dietary cholesterol and saturated fat are the cause of elevated plasma lipoproteins. Proponents of such an idea claim that these elevated level of lipoproteins are the cause of atherosclerosis, which in turn is the cause of cardiovascular disease. However, this theory is easily disproved using data from the literature. Firstly, dietary cholesterol and saturated fat do not alter lipoprotein levels in normal healthy individuals. Secondly, elevated lipoproteins are not the cause of cardiovascular disease, but merely associated with it. Thirdly, atherosclerosis does not always cause cardiovascular disease. Despite the extensive number of studies disproving this theory, the cholesterol theory of cardiovascular disease is still widely believed (and it is a belief). As a result, high fat diets are often seen as unhealthy and recommendations by the medical establishment are to avoid high level of dietary fat.
However, high fat diets are not detrimental to the health, and even have some benefits. For example, high intakes of the n-3 essential fatty acids are known to decrease cardiovascular disease risk. Proponents of the cholesterol theory of cardiovascular disease may argue that while the essential fatty acids are beneficial, saturated fat is not. However, research clearly shows benefits to high intakes of saturated fat in healthy men. For example, one study1 compared the effects of a high carbohydrate diet and a high fat diet at both maintenance and 75 % calorie intake in six healthy men. The high carbohydrate diet caused a significant increase in nitrogen excretion at the maintenance level calorie diet which equated to a 12 % increase in faecal and urinary losses. The high fat diet produced consistently higher nitrogen retention when compared to the high carbohydrate diet.
This data shows that higher nitrogen retention can be achieved at the same energy levels by increasing the fat content of the diet. Such a diet would be beneficial to those attempting to increase lean mass with resistance training. Interestingly, the high carbohydrate diet also increase plasma fasting triglyceride levels when compared to the high fat diet. This was particularly evident at the higher calorie intakes. This likely reflects an increased intakes of fructose. Fructose increases fasting triglycerides because it increases rates of de novo lipogenesis in the liver. The high fat diet also increased fat oxidation as measured by a lower respiratory quotient. Reduction of calories from maintenance to 75 % of intake caused decreases in triiodothyronine (T3) in both groups, which reflects the rapid decrease in resting metabolic rate associated with forced calorie restriction. The authors did not measure testosterone levels, but other data suggests high fat diets cause elevations in testosterone levels.
RdB
