A long-held idea in preventive medicine is that eating healthily, avoiding drinking, and maintaining a healthy weight will help prevent heart disease. However, a big new American study reveals that for millions of South Asians, this formula may not be sufficient. 

Northwestern Medicine researchers discovered that South Asian adults in the United States develop prediabetes, diabetes, and high blood pressure at significantly higher rates than other ethnic groups, often before the age of 45, despite reporting healthier diets, lower alcohol consumption, and similar exercise levels. 

The findings, published on February 11 in the Journal of the American Heart Association, come from a long-term study of 2,700 adults. Scientists monitored cardiovascular risk over a decade using data from two major cohort studies: MASALA, which focuses on South Asians, and MESA, which includes white, Black, Hispanic, and Chinese people. 

By the age of 45, over one-third of South Asian men had prediabetes, a disease characterised by elevated blood sugar levels that are not yet diabetic. In comparison, only 4% of white men were prediabetic at the same age. Around 25% of South Asian men had hypertension, or chronically elevated blood pressure, which strains the heart and arteries. 

Women demonstrated comparable tendencies. By the age of 45, nearly one in every five South Asian women had prediabetes, which was roughly double the prevalence reported in other ethnicities. By the age of 55, both South Asian men and women had at least double the risk of developing complete diabetes as white individuals. 

"The mismatch between healthier lifestyle behaviours and clinical risk was surprising," said senior author Dr. Namratha Kandula, a professor of general internal medicine and epidemiology at Northwestern University's Feinberg School of Medicine. "This paradox tells us we're missing something fundamental to what is driving this elevated risk among South Asians." 

One significant explanation is how the body accumulates fat. Many South Asians have a normal Body Mass Index (BMI), which is a standard measurement of weight in relation to height. But BMI does not indicate where fat is stored. 

The MASALA study found that South Asians have greater visceral fat, which is fat packed closely around internal organs such as the liver and pancreas. Visceral fat, as opposed to subcutaneous fat, is metabolically active and raises the risk of diabetes and heart disease. 

This discovery helps to answer a prevalent question: is BMI accurate for Indians? Not exactly. The "thin-outside, fat-inside" phenomenon occurs when a person seems small but has dangerously high levels of inside fat. 

Another frequently asked topic is why do South Asians develop diabetes at a lower weight? Scientists believe genetics, early-life diets, and metabolic variations may predispose them to insulin resistance, which is a disease in which the body struggles to metabolise sugar efficiently. 

South Asians make up around one-quarter of the global population, yet they account for nearly 60% of all heart disease cases. In the United States, they develop atherosclerosis—the narrowing of arteries caused by fatty plaque buildup—up to a decade earlier than the general population. 

Kandula stated that the study reveals a critical period. "We've now identified a critical window in the 40s when risk is already high, but disease is still preventable," she told me. 

Should South Asians screen before the age of 40? Experts are increasingly saying, "Yes." Early blood testing for fasting glucose, HbA1c (a three-month average of blood sugar), cholesterol, and blood pressure can help identify silent risk. 

Doctors are now advising patients to examine lipoprotein(a), a genetically determined cholesterol particle associated with arterial blockage that is frequently increased among South Asians. 

The study also addresses migration stress and lifestyle adjustments. Many participants are first-generation immigrants, and their early childhood diets and later sedentary employment behaviours may raise long-term risks. 

Chandrika Gopal, 58, a MASALA participant born in southern India, said the findings hit home. "This study resonates deeply with me," she expressed to me. "Even if we eat well, we may still be at higher risk. Living in a new country and adjusting to new foods and routines, it all adds up. 

Diet and exercise remain critical. However, for South Asians, they may not be adequate protection on their own. 

Early screening, culturally appropriate medical guidance, and awareness of genetic risk factors could help prevent thousands of premature heart attacks and diabetes cases. For a city known for its low obesity rates, the message is clear: don't wait until you're 50 to get your heart checked.