Researchers studied over 9,500 people to find a better way to predict who might develop heart disease. They discovered that a simple blood test measuring two types of cholesterol (triglycerides and HDL) works better than just looking at someone’s weight. The study found that people who looked healthy by weight but had unhealthy metabolism were actually at very high risk, while some heavier people with healthy metabolism had much lower risk. This suggests doctors should use blood tests along with weight measurements to get a clearer picture of heart disease danger.

The Quick Take

  • What they studied: Can a blood test that measures cholesterol types predict heart disease risk better than just knowing someone’s weight?
  • Who participated: 9,515 adults aged 35-55 from Iran, about half were overweight or obese, and they were grouped by both their weight and how healthy their metabolism appeared to be
  • Key finding: People who looked thin but had unhealthy metabolism had the highest heart disease risk (nearly 80% had concerning blood test results), while heavier people with healthy metabolism had much lower risk (only 18% had concerning results)
  • What it means for you: Your weight alone doesn’t tell the whole story about heart disease risk. A simple blood test measuring triglycerides and HDL cholesterol may be more important than the number on the scale. Talk to your doctor about getting these blood tests checked, especially if you’re concerned about heart health.

The Research Details

This was a cross-sectional study, which means researchers looked at a large group of people at one point in time rather than following them over years. They collected information about 9,515 adults in Iran, measuring their weight, taking blood samples, and asking about their lifestyle habits like exercise and smoking. The researchers then sorted people into four groups based on two things: whether they were overweight (using BMI, a weight-to-height measurement) and whether they had healthy metabolism (checked by looking at blood sugar, blood pressure, and cholesterol levels). They calculated a special score from each person’s blood test results that measures the balance between triglycerides (a type of fat in blood) and HDL cholesterol (the ‘good’ cholesterol). This score is called the Atherogenic Index of Plasma, or AIP for short.

This approach matters because doctors have realized that weight alone is misleading. Some heavy people are actually quite healthy, while some thin people have serious metabolic problems. By combining weight information with blood test results, researchers can identify who really needs help preventing heart disease. The AIP score is particularly useful because it’s simple to calculate from routine blood work that most people already get.

This study is fairly reliable because it included a large number of people (over 9,500), which makes the results more trustworthy. The researchers carefully adjusted their analysis to account for other factors that affect heart disease risk like age, exercise, smoking, and wealth. However, because this is a snapshot study rather than following people over time, we can’t be completely sure that the blood test results actually predict who will get heart disease—only that they’re connected. The study was done in Iran, so results might be slightly different in other countries with different populations.

What the Results Show

The study found striking differences in blood test results across the four groups. Among people who appeared thin and healthy, only 13.5% had concerning blood test results. But among thin people with unhealthy metabolism, nearly 80% had concerning results—that’s six times higher! Heavier people with healthy metabolism had only 18.6% with concerning results, while heavier people with unhealthy metabolism had 64.6%. When researchers did statistical analysis to account for age, exercise, smoking, and wealth, the patterns stayed strong. Thin people with unhealthy metabolism had 63 times higher odds of having a concerning blood test result compared to the healthiest group. Even heavier people with healthy metabolism had about twice the odds, showing that weight alone doesn’t determine risk.

The research confirmed that metabolic health is a major factor in heart disease risk, separate from weight. About half of the study participants were classified as heavier but metabolically healthy, which is important because it shows that not all heavy people are at high risk. The blood test measurements (triglycerides and HDL cholesterol) were strongly connected to metabolic health status, suggesting these simple measurements capture important information about how the body is functioning.

This study builds on growing evidence that weight alone is a poor predictor of heart disease. Previous research has shown that some overweight people live long, healthy lives while some thin people develop heart disease. This study confirms those findings and suggests that the AIP blood test score is a practical tool doctors can use. The findings align with recent medical thinking that metabolic health should be considered alongside weight when assessing heart disease risk.

The biggest limitation is that this study only looked at people at one moment in time, so we don’t know if the blood test results actually predict who will develop heart disease later. The study was done in Iran with a specific population, so results might be somewhat different in other countries or ethnic groups. The researchers couldn’t prove that the blood test causes heart disease risk—only that they’re connected. Additionally, the study relied on people’s reports of exercise and other habits, which might not be completely accurate.

The Bottom Line

If you’re concerned about heart disease risk, ask your doctor to check your triglycerides and HDL cholesterol levels (these are usually part of routine blood work). Don’t assume you’re healthy just because you’re thin, or unhealthy just because you’re heavy. Focus on metabolic health markers like blood sugar, blood pressure, and cholesterol levels. Regular exercise, healthy eating, and not smoking are important regardless of weight. These findings suggest that a simple blood test might be more useful than weight alone for understanding your real heart disease risk.

Everyone aged 35 and older should pay attention to these findings, especially if they have a family history of heart disease. People who are thin but have other health problems (high blood pressure, high blood sugar, or high cholesterol) should be particularly concerned. Even people who are overweight but have healthy blood pressure, blood sugar, and cholesterol levels can feel somewhat reassured, though they should still maintain healthy habits. People with metabolic syndrome or diabetes should definitely discuss their AIP score with their doctor.

Changes in blood test results typically take weeks to months to show improvement with lifestyle changes. If you start exercising regularly and eating healthier, you might see improvements in triglycerides and HDL cholesterol within 3-6 months. However, preventing heart disease is a long-term commitment—the real benefits show up over years and decades of maintaining healthy habits.

Want to Apply This Research?

  • Track your triglycerides and HDL cholesterol levels every 3-6 months by logging your blood test results. Create a simple ratio tracker (triglycerides divided by HDL) to monitor your AIP score over time and watch for improvements.
  • Set weekly goals for aerobic exercise (aim for 150 minutes per week) and log your activity in the app. Track meals to monitor saturated fat and refined carbohydrate intake, which directly affect triglycerides and HDL cholesterol. Set reminders for annual or semi-annual blood work to monitor your AIP score.
  • Create a dashboard showing your AIP score trend over time alongside your exercise minutes and dietary choices. Set alerts when blood test results come back so you can log them immediately. Compare your metabolic health markers (blood pressure, blood sugar, cholesterol) to see how lifestyle changes affect your overall cardiometabolic phenotype.

This research suggests associations between blood test results and heart disease risk, but cannot prove that one causes the other. These findings should not replace medical advice from your doctor. If you have concerns about heart disease risk, high cholesterol, or metabolic health, consult with a healthcare provider who can evaluate your individual situation, review your complete medical history, and recommend appropriate screening or treatment. This study was conducted in a specific population in Iran and results may vary in other populations. Always discuss any changes to diet, exercise, or health monitoring with your healthcare provider before starting.