Do humans gain excess weight by adding more fat cells (increase fat cell count) or by expanding the fat cells they already have (increase fat cell size)? Is one option better than the other? The answer depends on whether you are an adult or a child when you gain the weight. Research suggests that one probably is more troublesome than the other.
Let’s explore fat cell count versus fat cell size. Picture for a moment 2 bins of water balloons. One bin has 20 water balloons each filled to the size of golf balls or about 1 fl oz each. The other bin has 10 water balloons each filled to the size of a baseball or about 2 fl oz each. At this point, both bins contain 20 fl oz of water in balloons. Now, let’s fill each balloon in both bins with more water. At first, both bins are trending in the same direction with each balloon taking on additional water, but eventually the bin with only 10 water balloons will start to reach it’s max and each balloon will resist taking on more water. The bin with 20 water balloons has more available space so it will still be able to take on additional water. In this example the bin with more water balloons to start with will eventually be able to hold on to significantly more water.
How does this relate to fat cells? Let’s pretend that water balloons represent fat cells for a moment and the bin a human body. It’s important to know that research supports that children that gain excess weight do so by adding new fat cells and filling them up only partially before adding another cell. Adults that gain excess weight on the other hand do not easily add new fat cells, but rather fill up the one’s they created as a child. Pulling in our water balloon analogy, children that gain too much weight are like the bin with more water balloons. As that child ages, the body just keeps adding more and more golf ball balloons each time the child gains weight. If the child maintains a healthy weight he or she will keep the number of golf ball balloons fairly low.
Now let’s jump in a time machine and meet those children as young adults. The young adult that was overweight as a child will have a myriad of golf ball-sized balloons ready-built in their body while the young adult that was a healthy weight as a child will have much fewer golf ball-sized balloons ready-built. Let’s assume that both young adults start gaining weight. Eventually the golf balls will stretch to nearly a max size, the baseball size, and start resisting. The young adult that had many more golf balls to start with has the potential to gain substantially more weight before the body starts resisting.
Let’s hop back into our time machine and fast forward again until these two are middle-aged adults. They both take a vow to lose weight and through proper diet and exercise are successful. Recall that adults that lose weight do not reduce the number of balloons they have filled up but rather reduce the size of the balloon. They might both successfully lose 100 pounds. The one that had more balloons to deflate will just take a little out of each balloon, while the one that had less balloons will take more out of each balloon. The one that had more balloons will always have the tendency to more easily gain back the weight because the balloons are present in ample quantities and already stretched out to the size of a baseball.
Now that you’ll never quite see a water balloon fight in the same light again, let me reinforce the take home message from the research. Children that gain excess weight have a higher capacity to gain considerably more weight as an adult and it may be harder to keep that weight off if they try to lose it as an adult.