How Does Keto Affect Triglycerides?

Despite research repeatedly showing that eating fat, including saturated fat, is not harmful when restricting carbs simultaneously, there is still a lot of fatphobia lingering. ^[1] ^[2] This goes all the way back to the flawed research by Dr. Ansel Keys in the mid-twentieth century and the low-fat recommendations that followed. I cannot count how many times I’ve been asked if I was not worried about my triglycerides and cholesterol while following a ketogenic diet and whether I’m taking blood tests regularly. And yes, I do test my triglycerides and cholesterol levels at least yearly and they are perfect every year, after now seven years on a ketogenic diet.

So how does a ketogenic diet affect triglycerides and is there something to worry about?

What Are Triglycerides?

Triglycerides are the main constituents of body fat in vertebrates (including humans) and in vegetable fat. A triglyceride, also called a triacylglycerol or triacylglyceride, is a chemical compound in which a glycerol molecule and three fatty acid molecules are bound together by ester bonds. The fatty acids bound to the glycerol molecule can be saturated or unsaturated (mono-unsaturated or polyunsaturated). Triglycerides from the diet or from adipose tissue are also present in the blood, where it is transported to organs and tissues either to be burned as fuel or stored as fat.

Are Triglycerides and Cholesterol the Same?

Triglycerides are not be confused with cholesterol, which is also a type of lipid (sterol) that is synthesized by all animal cells, where it is an essential structural component in the cell membranes. There is not a direct correlation between cholesterol intake from food and the level of cholesterol in the blood. This is due to a decrease in cholesterol absorption and down-regulation of the body’s own cholesterol synthesis when dietary cholesterol intake is in excess. ^[3]

For more on cholesterol, read:

How Does Keto Affect Triglycerides?

So, what does the science say about the ketogenic diet and its effects on triglycerides?

Ketogenic Diet’s Effects on Triglycerides in Obesity and Metabolic Syndrome

In a randomized, controlled dietary intervention trial by Volek et al., published in 2009, 40 overweight subjects with atherogenic dyslipidemia (high levels of triglycerides and LDL, and low levels of HDL) were given a hypocaloric (1,500 kcal) carbohydrate-restricted diet (12% carbohydrate, 59% fat, 28% protein) or a hypocaloric (1,500 kcal) low-fat diet (56% carbohydrate, 24% fat, 20% protein) for 12 weeks. Twenty men and 20 women completed the study. ^[4]

The amount of saturated fat in the carbohydrate-restricted diet group was on average 36 g/day and in the low-fat diet group it was 12 g/day. Dietary cholesterol was significantly higher and fiber significantly lower on the carbohydrate-restricted diet group compared to the low-fat diet group. Even though the reductions in calories were similar in both groups, there was a twofold greater weight loss in the carbohydrate-restricted diet group compared to the low-fat diet group (10.1kg vs 5.2kg).

The carbohydrate-restricted diet significantly improved the features of atherogenic dyslipidemia compared to the low-fat diet:

Fasting triglycerides in the carbohydrate-restricted diet decreased 51% compared to 19% in the low-fat diet group.

HDL increased 13% in the carbohydrate-restricted diet and decreased 1% in the low-fat diet group.

The triglyceride/HDL ratio decreased 54% in the carbohydrate-restricted diet and 20% in the low-fat diet group.

The authors compared the weight loss to the change in triglyceride/HDL ratio and there was a very poor correlation for both groups, meaning that it was not the weight loss that affected the decrease in triglyceride/HDL ratio. Surprisingly, in the low-fat diet group, the subjects who had the largest weight loss showed the smallest change in triglyceride/HDL ratio.

In a meta-analysis published in 2020, 14 randomized controlled trials were included, where patients with overweight or obesity and with or without type 2 diabetes were given a ketogenic diet. ^[5] Irrespective of whether the patients had diabetes or not, the ketogenic diet led to substantial weight reduction and decreased triglyceride levels, and in diabetes patients, HDL increased.

The authors conclude:

“Our study findings confirmed that ketogenic diets were more effective in improving metabolic parameters associated with glycemic, weight, and lipid controls in patients with overweight or obesity, especially those with preexisting diabetes, as compared to low-fat diets. This effect may contribute to improvements in metabolic dysfunction-related morbidity and mortality in these patient populations.”

Ketogenic Diet’s Effects on Triglycerides in Normal Weight and Normolipidemic Persons

There are many studies showing a decrease in triglycerides in overweight or obese persons placed on a keto diet. The study participants often have prediabetes, metabolic syndrome, or diabetes. In these studies, the subjects often lose weight, and it is hard to know for sure if the benefits on the metabolic markers are due to the weight loss, the ketogenic diet, or both.

In a study by Sharman et al., published in 2002, 20 normal-weight men with normal lipid values (normolipidemic) were included. Twelve men switched from their habitual diet (47% carbohydrate, 32% fat, 17% protein) to a ketogenic diet (8% carbohydrate, 61% fat, 30% protein) and eight control subjects consumed their habitual diet for 6 weeks. ^[6]

In the men following a ketogenic diet, there was a significant decrease in fasting triglycerides by 33% and a decrease in lipids in the blood after a fat-rich meal (postprandial lipemia) by 29%.

LDL was unaffected and HDL increased in 11.5% in the men on the ketogenic diet. There were no significant changes in blood lipids in the control group.

The authors conclude that this study documents the effects of a ketogenic diet on cardiovascular disease biomarkers independent of weight loss, and the results suggest that a short-term ketogenic diet does not have a deleterious effect on cardiovascular disease risk profile and may improve the lipid disorders characteristic of atherogenic dyslipidemia.

Should You Worry About Triglycerides on Keto?

The bottom line is that people with elevated triglycerides when starting on a ketogenic diet will almost always see a reduction in triglycerides when they adapt to and maintain a ketogenic diet.

People with metabolic syndrome can see a reduction of serum triglycerides by half on average. Increases in triglycerides while following a well-formulated ketogenic diet are rare, but they do happen. This can be due to a too high carbohydrate or alcohol intake. Try to reduce both and take another blood test.

Be aware that serum triglycerides should be measured fasted when on a ketogenic diet. After a ketogenic meal with a high fat content, triglycerides will be elevated in the blood for several hours.

For more articles about fat, read:

Maria Edwards

Maria Edwards is a ketogenic researcher in Copenhagen, Denmark, with a M.Sc. in Clinical Nutrition and a B.Sc in Food Science, Health and Nutrition. Her interest in the ketogenic diet started in 2016 when she initiated the diet as a treatment for her bipolar disorder and experienced its profound effects on herself. Today she is completely medicine free and almost symptom free due to the ketogenic diet and is doing research with the ketogenic diet in severe brain injury and PTSD.