It is well known that carrying excess visceral fat tissue increases risk of age-related disease, shortens life expectancy, and raises lifetime medical expenditure. The more fat tissue, the worse the outcome, but even being modestly overweight rather than obese still produces a negative impact on long term health. This is the story told in a great many epidemiological studies with large patient populations. Does this mean that obesity accelerates aging, however? It might be surprising to find out that this isn't a question that has an easy or a straightforward answer.

In order to talk about whether aging is accelerated, one has to have a strong understanding of what causes aging. If we can list specific causative mechanisms of aging, and then measure their state, then we might be able to say whether or not aging is accelerated or slowed by a given circumstance. In the SENS view of aging, the root cause is accumulation of cell and tissue damage that arises as a side-effect of the normal operation of cellular metabolism. Things like the presence of lingering senescent cells or cross-links in the extracellular matrix. We can make the argument that a lifestyle choice that increases the pace at which senescent cells emerge in tissues is in fact an acceleration of aging. We can similarly argue that environmental circumstances such as smoking or chemotherapy that do the same have some component of accelerated aging in the harm that they cause.

Excess visceral fat tissue does in fact add to the presence of senescent cells. It also causes chronic inflammation via several other mechanisms, distinct from that of the inflammatory signaling produced by senescent cells. The chronic inflammation of aging is a downstream consequence of causes of aging, but it is a prominent feature of aging and causes further issues in and of itself, speeding up the progression of all of the common age-related conditions. Could upregulating inflammation directly, without going via one of the underlying causes of aging, be called an acceleration of aging? Perhaps not. Perhaps it should just be called harm and damage, and fall into the same category as breaking a bone and the long-term consequences that result from that sort of injury. So we might say that fat tissue accelerates aging in some senses, but in others it is not an acceleration of aging, just a harm.

This may be a matter of semantics and definitional games. The lesson at the end of the day is to avoid putting on excess weight, as even therapies targeting the causes of aging cannot prevent all of the long-term damage that being overweight will generate. Different perspectives are always interesting, however. Today's open access paper, noted below, looks at the question of whether or not obesity accelerates aging through the filter of the Hallmarks of Aging, a more recent catalog of potential causes and mechanisms of aging that overlaps to some degree with the causes of aging listed in the SENS proposals, but has significant differences. Some of the Hallmarks are clearly downstream consequences or markers of the progression of aging from the SENS perspective, for example.

Obesity May Accelerate the Aging Process