The number of fat cells in our bodies is constant throughout adult life for both lean and overweight people. When adults gain fat weight, it’s because our individual fat cells store more fat, thereby enlarging. We don’t gain more fat cells. Conversely, when we lose weight, the fat cells shrink.
Our number of fat cells is set during childhood and adolescence. Lean individuals generally have fewer fat cells than overweight people.
In many living tissues, individual cells gradually die off and are replaced by new cells. For example, we shed dead skin cells all the time, but they are replaced just as quickly by new skin cells. A red blood cell lives three months then dies and is replaced. The percentage of cells that die and are replaced over a period of time is called “turnover.”
Researchers in Stockholm recently studied the turnover of fat cells in humans. They measured turnover by analysing the incorporation of carbon-14 derived from nuclear bomb tests in genomic DNA. They found that 10% of fat cells die off and are renewed yearly at all adult ages in both skinny and overweight people.
Well, if 10% of your fat cells die every year, what if you could prevent them from being replaced with new ones? You would lose weight, as long as your remaining fat cells didn’t swell with more stored fat. Next year, another 10% of your fat cells die, and so on.
How can we prevent dead fat cells from being replaced by new ones? Nobody knows . . . yet. You can bet that pharmaceutical companies are thinking about this.
But I wouldn’t hold my breath. Pharmaceutical intervention will not be available for at least eight to 10 years, if ever.
We already have available, in 2009, a tried and true method for reducing fat mass: Eat Less, Move More.
Reference: Spalding, K.L., et al. Dynamics of fat cell turnover in humans. Nature, 453 (2008): 783-787. Epub May 4, 2008. PMID: 18454136.