Why your waistline in midlife may decide how fast your brain ages

Team TOI PlusTNN & Agencies
May 11, 2026 | 12:28 IST
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A long-term study has found that visceral fat, not just overall body weight, is closely linked to brain aging and cognitive performance. It also suggests that waist size and blood sugar may matter more than BMI alone

Is body weight the real warning sign, or is it where the fat sits? This is at the heart of a new Nature Communications study on midlife health. Researchers who followed 533 adults from four earlier lifestyle trials found that visceral fat — the fat stored deep inside the abdomen — is more closely linked to later brain ageing and cognitive performance than body mass index, or BMI, or overall weight loss. While the study does not prove that belly fat directly causes brain shrinkage, it strengthens a growing argument in medicine that the waistline may reveal risks that the weighing scale can miss.

For decades, obesity has been treated largely as a number: BMI. It is simple, cheap and widely used. But while BMI can tell whether a person’s weight is high for their height, it cannot tell whether that weight comes from muscle or fat. More importantly, it cannot show where fat is stored.
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