Many people notice that their waist gets bigger as they get older, even if they don’t gain a lot of weight. This extra belly fat is more than a look‑problem – it can slow metabolism, speed up aging, and raise the risk of diabetes and heart disease.
What Scientists Learned
Researchers at City of Hope and UCLA studied mice and human tissue to find out why fat builds up around the middle with age. They focused on the body’s main fat‑storage tissue, called white adipose tissue (WAT).
New Fat‑Making Cells Appear With Age
Old mice have a type of stem cell inside their fat called an adipocyte progenitor cell (APC). When the scientists moved these old APCs into young mice, the young mice suddenly grew many new fat cells. The opposite experiment – putting young APCs into old mice – created only a few new fat cells.
This showed that the older APCs themselves are wired to make lots of fat, no matter where they are placed.
A Fresh Kind of Stem Cell
During middle age, some APCs change into a brand‑new stem‑cell group that the researchers named “committed pre‑adipocytes, age‑specific” (CP‑As). These CP‑A cells are very good at turning into fat cells, and they appear only as we get older.
What Triggers the CP‑A Cells?
The team discovered that a signaling pathway called the leukemia inhibitory factor receptor (LIFR) tells CP‑A cells to multiply and become fat cells. Young mice do not need this signal, but older mice rely on it to make more belly fat.
Do Humans Have the Same Cells?
Using the same single‑cell RNA‑sequencing technique, researchers examined human fat samples from people of different ages. They found cells that looked a lot like the mouse CP‑As, and they were more common in middle‑aged donors. These human CP‑A‑like cells also made many new fat cells in the lab.
Why This Matters
Understanding that new fat cells keep forming because of CP‑A cells gives scientists a possible target for future medicines. If we can block the LIFR signal or remove CP‑A cells, we might be able to slow or stop the belly‑fat that often comes with getting older.
More research is needed, but the discovery opens a hopeful path toward healthier aging and a flatter waist.