Study finds aging may spur belly fat-producing stem cells

Aging may be switching on specialized stem cells that give the body a greater capacity to build belly fat, turning middle-age weight gain into a question of cell biology as much as calories.

Researchers at City of Hope and UCLA, including Qiong (Annabel) Wang, Xia Yang, Adolfo Garcia-Ocana, Guan Wang and Gaoyan Li, identified a new age-associated stem cell population called committed preadipocytes, age-specific, or CP-As. The work, published in Science on April 25, 2025, used mouse transplantation experiments and single-cell RNA sequencing to show that older adipocyte progenitor cells could become CP-As and actively generate new fat cells, especially around the belly. The team also tied the process to the LIFR signaling pathway at The Arthur Riggs Diabetes & Metabolism Research Institute in Duarte, California.

The researchers also found CP-As in human tissue samples, strengthening the case that the mechanism may matter beyond laboratory animals. The central finding was not simply that fat cells grew larger with age, but that aging appeared to increase the body’s ability to make new fat cells in abdominal tissue. That matters because visceral and abdominal fat are closely associated with higher risks of diabetes and cardiovascular disease.

The finding offers a biological explanation for a complaint familiar to many older adults: stubborn belly fat that seems to arrive even when eating habits do not change dramatically. It shifts the focus away from a purely behavioral or willpower-based explanation and toward the possibility that aging changes the tissue itself, making the abdomen more prone to storing fat.

The study is still early and does not point to an immediate clinical treatment. Even so, it gives obesity researchers a target that could matter for older adults if the mechanism holds up in further human studies. Instead of trying only to reduce fat after it has accumulated, future therapies could aim to block the CP-As themselves or interfere with the LIFR pathway before new abdominal fat cells form.