Researchers looked at whether the ketogenic diet—a popular low-carb, high-fat eating plan—might damage heart health over time. They compared 28 people who followed the keto diet for more than 5 years with 28 similar people who didn’t. Using ultrasound scans, they measured the thickness of artery walls in the neck. They found that keto dieters had slightly thicker artery walls, which could be an early warning sign of heart problems. However, their blood pressure, weight, and cholesterol levels were all normal. The findings suggest doctors should monitor people on long-term keto diets more carefully, but more research is needed to understand what this really means.

The Quick Take

  • What they studied: Whether following a ketogenic (keto) diet for many years might cause early signs of heart artery damage, even when other health markers look normal.
  • Who participated: 56 people total—28 who had been eating keto for at least 5 years (ages 6-49) and 28 similar people who weren’t on the diet. Both groups were matched by age and gender.
  • Key finding: People on the keto diet had thicker artery walls in their neck (0.62 mm vs. 0.53 mm, p < 0.001), and this difference got bigger as people got older. This thickness is considered an early warning sign of potential heart problems.
  • What it means for you: If you’re considering or currently following a keto diet long-term, this suggests you should have regular heart health check-ups. However, this is just one small study, and the people on keto still had normal blood pressure, weight, and cholesterol—so don’t panic. Talk to your doctor about monitoring.

The Research Details

This was a cohort study, which means researchers followed two groups of people and compared them. One group had been eating a ketogenic diet for more than 5 years, and the other group hadn’t. Both groups were similar in age and gender so the comparison would be fair. The researchers used ultrasound machines (the same technology used to see babies during pregnancy) to measure how thick the inner layers of arteries in the neck were. Thicker artery walls can be an early sign that plaque is building up, which could lead to heart disease later. They also checked traditional heart risk factors like blood pressure, weight, and cholesterol levels in the keto group to see if these were abnormal.

This research approach is important because it looks at what happens to real people over a long time, rather than just testing something in a lab. The keto diet has become very popular, but we don’t know much about its long-term effects on heart health. By comparing people who’ve been on it for years with similar people who haven’t, researchers can spot potential problems early. The ultrasound measurement (called carotid intima-media thickness or cIMT) is valuable because it can detect early artery damage before someone has a heart attack or stroke.

This study has some strengths: it used objective measurements (ultrasound scans) rather than just asking people questions, and it compared similar groups. However, it’s relatively small (only 28 people per group), so the results might not apply to everyone. The study was published in a peer-reviewed journal, which means other experts reviewed it before publication. The researchers were honest about measuring both the keto group and controls, which reduces bias. One limitation is that we don’t know if the thicker arteries are actually dangerous or if they’ll cause problems later.

What the Results Show

The main finding was that people who followed the ketogenic diet for more than 5 years had thicker artery walls in their neck compared to people who didn’t follow the diet. Specifically, the keto group’s artery walls measured 0.62 millimeters thick on average, while the control group’s measured 0.53 millimeters—that’s a difference of about 0.09 millimeters. While this might sound tiny, it was statistically significant, meaning it’s unlikely to have happened by chance. The difference became more noticeable as people got older. For example, in older participants, the keto group had 0.69 mm thick arteries versus 0.60 mm in the control group. Interestingly, it didn’t matter whether people followed the classical keto diet or a modified version—both groups showed similar artery thickening.

When researchers checked traditional heart disease risk factors in the keto group, they found something surprising: blood pressure was normal, body weight was normal, and blood lipid (cholesterol) levels were normal. This is actually good news because it means the keto diet wasn’t causing obvious problems in these common health markers. However, the thicker arteries suggest that something else might be happening inside the blood vessels that isn’t captured by these standard measurements. This is why researchers think the artery thickness measurement might be a more sensitive early warning sign than the usual tests doctors do.

Previous research has raised concerns about whether high-fat diets might harm heart health, but most studies have looked at short-term effects or different types of diets. This study is one of the first to specifically examine long-term ketogenic diet use and early signs of artery damage. Some earlier research suggested that keto diets might improve certain cholesterol levels, which is why the normal cholesterol results here are interesting. The finding of thicker arteries despite normal cholesterol suggests that the keto diet might affect heart health through different pathways than researchers previously thought. This adds to the growing body of evidence that long-term effects of keto need more study.

This study has several important limitations to keep in mind. First, it’s small—only 28 people per group—so the results might not apply to everyone. Second, it’s a snapshot in time; researchers didn’t follow people over years to see if thicker arteries actually led to heart problems. Third, we don’t know why the arteries got thicker—it could be from the diet itself, or from other factors the researchers didn’t measure. Fourth, the study included people of very different ages (6 to 49 years old), and we don’t know if the findings apply equally to children versus adults. Finally, the study didn’t look at how long people had been on the diet before the 5-year mark, so we don’t know when the artery thickening started.

The Bottom Line

If you’ve been following a ketogenic diet for several years, consider asking your doctor about getting an ultrasound scan of your carotid arteries as part of your regular health check-ups. This is a low-risk, non-invasive test. However, this single study isn’t strong enough to say you should stop the keto diet—more research is needed. If you’re thinking about starting a long-term keto diet, discuss it with your doctor first, especially if you have other heart disease risk factors. The confidence level for these recommendations is moderate because this is a small study, but it raises important questions worth discussing with healthcare providers.

This research is most relevant to people who have been or plan to be on a ketogenic diet for many years. It’s especially important for people with a family history of heart disease or those who already have heart disease risk factors. Parents considering keto for their children should definitely talk to a pediatrician. People on keto for short-term weight loss (a few months) probably don’t need to worry based on this study alone. However, anyone on long-term keto should be aware of these findings and discuss monitoring with their doctor.

Artery thickening appears to develop gradually over years—this study looked at people who’d been on keto for at least 5 years. You wouldn’t expect to see changes in a few weeks or months. If you start monitoring with ultrasound scans, you might not see significant changes for several years. However, starting heart-healthy habits now (like regular exercise and eating plenty of vegetables) can help protect your arteries regardless of your diet choice.

Want to Apply This Research?

  • Track your cardiovascular health markers monthly: blood pressure (if you have a home monitor), weight, and any heart-related symptoms like chest discomfort or unusual shortness of breath. Record these in a health app to share with your doctor.
  • If you’re on a long-term keto diet, add a weekly reminder to schedule a doctor’s appointment for cardiovascular monitoring. Use the app to set a goal of getting an ultrasound scan of your carotid arteries annually or as recommended by your doctor.
  • Create a long-term health tracking dashboard that includes: (1) annual carotid ultrasound results if your doctor recommends them, (2) quarterly blood pressure and cholesterol checks, (3) monthly weight tracking, and (4) notes about any new heart-related symptoms. Share this data with your healthcare provider during check-ups.

This research suggests a possible link between long-term ketogenic diet use and early signs of artery thickening, but it does not prove that the keto diet causes heart disease. This is a small study, and more research is needed. If you’re following or considering a ketogenic diet, especially long-term, please discuss this research with your doctor or a registered dietitian. Do not make major changes to your diet based on this study alone. This information is for educational purposes and should not replace professional medical advice. If you experience chest pain, shortness of breath, or other heart-related symptoms, seek immediate medical attention.