Is the keto diet safe for long-term heart health?

Does keto help or hurt your heart in the long run?

The answer depends on which heart risk factor you look at. On the positive side, a 2024 case study of a person with type 1 diabetes who followed a strict keto diet for 10 years found they achieved a hemoglobin A1c (a measure of average blood sugar) of 5.5% — a level seen in fewer than 1% of people with type 1 diabetes — and had below-average cardiovascular risk compared to other people with the same condition [1]. Similarly, a 3-month trial in seven adults with bipolar disorder found that keto reduced triglycerides by 30% (from about 135 to 94 mg/dL) and lowered a key inflammatory marker (hsCRP) by 45% [3]. These are meaningful improvements, since high triglycerides and inflammation are linked to heart disease.

But there are also concerning findings. A 2025 study of 28 patients who had been on keto for more than 5 years found that their carotid artery walls were 17% thicker than those of matched controls (0.62 mm vs. 0.53 mm) — a difference that grew larger with age [2]. Carotid intima-media thickness is an early sign of atherosclerosis, or hardening of the arteries, and is a predictor of future heart attacks and strokes. That same study noted that blood pressure, body mass index, and standard cholesterol levels were all normal in the keto group, meaning the artery thickening happened even when those usual risk markers looked fine [2].

Why does keto raise 'bad' cholesterol but also improve other markers?

Keto diets are high in fat, so it's not surprising that they often raise LDL cholesterol — the so-called 'bad' cholesterol. In the 3-month bipolar study, LDL cholesterol increased by 9% (from about 156 to 170 mg/dL) and total cholesterol rose 3% [3]. But at the same time, HDL cholesterol (the 'good' kind) increased by 5%, and triglycerides dropped 30% [3]. This mixed pattern is common: keto tends to shift the lipid profile in a direction that is not clearly good or bad for heart health. The 2025 study of children on keto for at least 2 years found that their 'atherogenic index of plasma' (a combined risk score) was high, but it did not correlate with actual artery thickness [4]. So while LDL goes up, other protective changes may partly offset that risk — but the net effect over decades is still unknown.

One important nuance: the type of fat matters. The studies here used different keto formulations (classical high-saturated-fat versions vs. modified versions with more unsaturated fats), and the artery-thickening effect was similar regardless of which version was used [2]. This suggests that the overall state of ketosis, not just the fat composition, may drive some of the vascular changes.

Who should be cautious about long-term keto, and what should they track?

People with existing heart disease risk factors — especially high LDL cholesterol, a family history of early heart attacks, or diabetes — should be cautious. The 2025 study that found thicker carotid arteries in long-term keto users did so in a group that included children and adults, and the effect increased with age [2]. That means the longer you stay on keto, the more the artery wall thickening may accumulate. The same study recommended that anyone on long-term keto should get regular carotid ultrasound to check for early signs of atherosclerosis [2].

On the other hand, for people with type 1 diabetes, the blood sugar benefits of keto can be dramatic. The 10-year keto patient in the 2024 case study achieved near-normal blood sugar with very low insulin doses, and their heart function tests (including echocardiography and arterial stiffness measurements) were all in the low-risk range [1]. This suggests that for some high-risk groups, the benefits of better blood sugar control may outweigh the potential harms of higher LDL or artery thickening — but this is a trade-off that needs to be managed with a doctor.

Finally, keto is not risk-free for other organs. A 2025 study in children found that bone mineral density was significantly reduced after 2 years on keto, similar to the reduction seen with standard anti-seizure drugs [4]. And the 3-month bipolar study found that homocysteine (a heart risk marker) increased by 18% and advanced glycation end products (AGEs, linked to vascular damage) more than doubled [3]. These are additional reasons why long-term keto requires careful medical supervision, not a 'set it and forget it' approach.

About These Sources

This answer is built on 5 peer-reviewed studies — published from 2022 to 2025, 4 from 2024 or later, 3 in Q1 journals, collectively cited 64 times — selected as the most relevant from 5 studies that passed quality screening, drawn from 76 papers retrieved from a database of over 500 million.

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