As noted in a previous post on Trans Fatty Acids (TFAs), Mozaffarian et al. (2006) conducted a meta-analysis of TFAs and cardiovascular disease and noted the following effect on serum lipids:
As compared with the consumption of an equal number of calories from saturated or cis unsaturated fats, the consumption of trans fatty acids raises levels of low-density lipoprotein (LDL) cholesterol, reduces levels of high-density lipoprotein (HDL) cholesterol, and increases the ratio of total cholesterol to HDL cholesterol, a powerful predictor of the risk of CHD.21 Trans fats also increase the blood levels of triglycerides as compared with the intake of other fats,20 increase levels of Lp(a) lipoprotein,22 and reduce the particle size of LDL cholesterol,23 each of which may further raise the risk of CHD. Thus, trans fatty acids have markedly adverse effects on serum lipids.
Sounds familiar to what happens when people increase their consumption of sugar and refined carbohydrates. Chronic, long-term consumption of excess carbohydrates (perhaps in particular, sugar, or more specifically, fructose) induces many aspects of the metabolic syndrome, including many of the same effects on serum lipids shown above when looking at TFA consumption.
With metabolic syndrome, we see a host of issues, including insulin resistance, inflammation, glucose intolerance, hypertension, dyslipidemia, and diabetes clustered together.
Most studies show that when compared to a diet restricted in carbohydrates, the consumption of carbohydrates makes LDL particles smaller and denser (more atherogenic), lowers HDL, increases blood pressure, and increases triglycerides, many of the same effects seen with TFA consumption.
When we eat low-carbohydrate diets, our "good" HDL tends to go up, our LDL becomes larger and fluffier (less atherogenic), our blood pressure goes down, and our triglycerides plummet. Does this mean a low-carbohydrate diet is beneficial to health?
Yes and no. While it appears "beneficial," for me, it's more of an indicator of our serum lipids "correcting" to levels that we are supposed to find in a healthy individual. In other words, if we look at a population of people who are chronically over-consuming sugar and refined carbohydrates, their serum lipids are going to be abnormal. When they go on a low-carbohydrate diet, they're correcting the abnormality and the associated lipids will become more "favorable" (while I would argue that they're just trending toward a normal, healthy human being) depending on which MD or researcher you ask.
So it is with weight "loss," water "loss," lipid and metabolic "benefits" of a low-carbohydrate diet. There is nothing magical about restricting carbohydrates, rather it's closer to the kind of diet that we've been eating and are presumably genetically well-adapted to eat, and any loss of weight and water, any beneficial effects on serum lipids are just a correction rather than an improvement in health.
Carbohydrate-restriction fixes things that carbohydrates break.
Benefits v. Correction:
- A restricted-carbohydrate diet doesn't make you lose weight; it corrects your weight.
- A restricted-carbohydrate diet doesn't make you lose water weight; it corrects your water weight.
- A restricted-carbohydrate diet doesn't improve serum lipids; it corrects serum lipids.
- A restricted-carbohydrate diet doesn't improve health; it corrects unhealthiness.