Keto Diet Raises LDL — Does This Apply to You?

A recent study reports a significant rise in low-density lipoprotein (LDL) cholesterol for young, healthy women following a ketogenic diet. What do these results mean for you?

The study, published in the journal , randomized 17 women to follow either a ketogenic diet (less than 25 grams of carbs and 77% from fat calories) - or a control diet for four weeks. They then had a "washout" period and started on the other diet.

The authors conclude that the women on a keto diet saw a significant rise in their LDL cholesterol. There was a rise in both the larger LDL and the smaller, denser LDL with an overall slight decrease in average LDL size.

The participants also saw a slight increase in triglycerides on the keto diet, along with a decrease in blood sugar and insulin. In addition, the participants had more significant weight loss while on the keto diet, but the authors did not include that data in their report.

We have written numerous articles about the many benefits of following a keto diet. It seems LDL cholesterol is the most significant remaining concern, and this study may add fuel to that fire.

However, it is worth noting that the majority of the data suggest people with obesity or type 2 diabetes who follow a ketogenic diet do not, on average, see a significant LDL increase. A meta-analysis of over 1,600 subjects demonstrates no significant increase in LDL and another reports overall improvement in cardiac risk factors.

The studies from Virta Health report no change in apolipoprotein B (Apo B) (a more accurate measurement of LDL), decreased overall cardiovascular risk score, and a shift from small, dense LDL to the less atherogenic larger LDL particles.

Why is the current trial different?

First, the participants are healthy volunteers without obesity, diabetes, metabolic dysfunction, insulin resistance, or any of the other conditions keto diets frequently improve. This is a crucial point as it limits how applicable the results are to most people starting a keto diet to help underlying health concerns.

Second, somewhat connected to point number one, all but one of the participants started with pattern A LDL (the larger, less dense LDL). That may be why they didn't show an improvement in LDL size - it was already good and didn't need improving!

And it's worth noting that the one woman who started with pattern B LDL improved to pattern A after four weeks on a keto diet.

Third, this was a very short study lasting only four weeks, and the authors suggested the subjects were actively losing weight. Prior studies report an initial rise in LDL cholesterol with weight loss that can normalize over time with weight maintenance. Would that have happened in this trial? That is unknown as the trial was too short to tell.

Fourth, the women followed a relatively low-protein, high-fat keto diet. Would the results have been the same on a higher protein (25 to 30% of calories) and a lower fat (around 65% of calories) diet?

Lastly, what does elevated LDL cholesterol mean to the overall health risk for these subjects? The standard thinking is that any elevated LDL cholesterol is concerning. But for a group of young, healthy women without other risk factors, how substantial is that increased risk? Chances are, it is minimal, if at all perceptible for this population.

Here are four main takeaways:

1. Why are you on a ketogenic diet? Many people may be better off on a higher protein, moderate low-carb diet instead of a ketogenic diet, especially if they are young, healthy, and aren't treating an underlying health condition.
2. Reacting to labs after only four weeks on a diet is premature and doesn't represent a diet's long-term prognostic effect.
3. If you have obesity, type 2 diabetes, metabolic syndrome, insulin resistance, etc., this trial does not apply.
4. We lack data in this specific, healthy cohort to help us understand the impact of isolated elevated LDL cholesterol.

At Diet Doctor, we know a great deal of confusion exists around the topics of LDL cholesterol and low-carb diets. You can read more about our thoughts on cholesterol on a low-carb diet, whether we changed our opinion on LDL, and what you can do to lower your LDL on a low-carb diet.

Thanks for reading,
Bret Scher, MD FACC

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