Why obesity duration damages the heart across decades

A lifelong clock

Does living with obesity for five years affect your heart the same way as carrying it for twenty-five? A study tracked 4,901 people born in 1958, measuring their body mass index from age 7 up to 62. The team wanted to know if obesity duration damages the heart independently of a person's current weight.

Tracking wear and tear

Think of carrying a heavy backpack. A quick walk with heavy straps might cause little trouble, but hiking with it for decades slowly wears out the frame. To test this, researchers checked three blood biomarkers at age 62. They measured hs-cTnI, a protein released when heart muscle cells suffer injury. They also measured NT-proBNP, which signals stretched heart walls, and GDF-15, a marker of cellular stress.

The results showed that time matters. Every extra year of living with obesity was linked to a 0.41% rise in hs-cTnI. In addition, ever having experienced obesity was tied to 11.00% higher hs-cTnI in men, though not in women. Meanwhile, each unit of mean excess BMI—the average amount weight stayed above the obesity cutoff—raised NT-proBNP by 4.02% and hs-cTnI by 2.00%.

The 25-year threshold

Stress markers showed a sharp turning point. Levels of NT-proBNP and GDF-15 stayed relatively steady until obesity lasted beyond roughly 25 years. After that point, each additional year was tied to a 1.80% rise in NT-proBNP and a 0.81% rise in GDF-15. The backpack straps finally begin to tear.

What we still don't know

This work comes from a preprint, meaning independent scientists have not fully peer-reviewed it yet. The study shows an association, not direct proof that time alone caused the changes. We still do not know the exact biological triggers behind the 25-year jump. It also remains unknown whether reversing obesity in later years can return these heart markers to normal levels.