Like much of my writing, researching fat or ‘adipose’ cells was inspired by a conversation with a client.
A while ago the Daily Mail reported that most overweight people who lost fat quickly regained it
We talked about why this might be
I suggested that the way they lost weight was possibly not sustainable so they got bored and reverted to their old habits.

I suggested that it may be because people who have been overweight have more and larger fat cells.
Which is what made me look into this.

Have you ever wondered what fat is?

When a person “gets fat” — gains weight — what is actually happening inside the person’s body?

What are “fat cells” and how do they work?


Fat tissue is made up of fat cells, which are a unique type of cell.

You can think of a fat cell as a tiny plastic bag that holds a drop of fat.The human body contains two types of fat tissue:

White fat is important in energy metabolism, heat insulation and mechanical cushioning.

Brown fat is found mostly in newborn babies, between the shoulders, and is important for thermogenesis (making heat). Since adult humans have little to no brown fat, we’ll concentrate on white fat in this article.

White fat cells are large cells that have very little cytoplasm, only 15 percent cell volume, a small nucleus and one large fat droplet that makes up 85 percent of cell volume

Where do we store fat?

Fat, or adipose tissue, is found in several places in your body.
Generally, fat is found underneath your skin (subcutaneous fat).

There’s also some on top of each of your kidneys.
In addition to fat tissue, some fat is stored in the liver, and an even smaller amount in muscle.
Where fat is concentrated in your body depends upon whether you are a man or woman:

  • An adult man tends to carry body fat in his chest, abdomen and buttocks, producing an “apple” shape.
  • An adult woman tends to carry fat in her breasts, hips, waist and buttocks, creating a “pear” shape.

The number of fat cells grows through childhood and adolescence, but generally stabilizes sometime in late adolescence. 
After that, your fat-cell count stays the same.


  1. People on the fast track to obesity pack on their fat cells more quickly in childhood.
  2. Naturally lean people have fewer fat cells, but keep producing them until the age of 18 or 19.
  3. Overweight adults have larger fat cells and may have more fat cells 

What happens when we lose fat?

When you “lose” body fat, the fat cell (also called an adipocyte) does not go anywhere or “move into the muscle cell to be burned.

The fat cell itself, (unfortunately) stays right where it was – under the skin in your thighs, stomach, hips, arms, etc., and on top of the muscles – which is why you can’t see muscle “definition” when your body fat is high.

Fat is stored inside the fat cell in the form of triaglycerol.

The fat is not burned right there in the fat cell, it must be liberated from the fat cell through somewhat complex hormonal/enzymatic pathways. When stimulated to do so, the fat cell simply releases its contents (triaglycerol) into the bloodstream as free fatty acids (FFA’s), and they are transported through the blood to the tissues where the energy is needed.

Fat Cells Shrink and Expand

Remember, body fat is basically just a reserve source of energy and fat cells are the like the storage tanks. Unlike a gas tank in your car which is fixed in size, however, fat cells can expand or shrink in size depending on how “filled” they are.

Picture a balloon that is not inflated: It’s tiny when not filled with air – maybe the size of your thumb. When you blow it up with air, it can expand 10 or 12 times it’s normal size, because it simply fills up.

That’s what happens to fat cells: They start as nearly empty fat storage “tanks” (when you are lean), and when energy intake exceeds your needs, your fat cells “fill up” and “stretch out” like balloons filling up with jelly (not a pretty picture, is it?)

So you don’t actually “lose” fat cells, you “shrink” or “empty out” fat cells.

Even after marked weight loss, the body never loses adipocytes.

AS a rule, to facilitate changes in weight, the adipocytes in the body merely gain or lose fat content.

The fat globules within each cell increase as you
store more fat. 

Life and Death of Fat Cells

During adulthood, about 8% of fat cells die every year only to be replaced by new ones.
As a result, adults have a constant number of fat cells, even those who lose masses of weight.
Instead, it’s changes in the volume of fat cells that causes body weight to rise and fall.

Research has shown that obese adults produce about twice as many new fat cells every year as lean ones.
However, obese adults also have more fat cells anyway than lean ones, and the proportion of new cells added is the same in both groups.
These similar birth rates are matched by similar death rates.

However compared to their lean peers, obese children add new fat cells at twice the rate, which is why they end up with a bigger complement of fat cells

Anyone can shrink their fat cells and get lean if they work hard and eat right. 
Remember, fat is what fills the fat cells.
You can still lose the fat and shrink the cells

So to return to my original question..
Do overweight people find it harder to lose and keep off weight?

The more fat cells you have, the more difficult it is to lose fat.

People who have built up a large supply of fat cells in childhood that is constantly replenished throughout adult life are at a disadvantage.

Take-home lessons:

1. Calories count!
The signal that triggers your body to release adipose from fat cells is an energy deficit
     You have to burn more than you eat.

  1. Cut calories conservatively.
    Starving yourself may cause quick weight loss at first, but never works long term because it actually decreases the activity of fat burning enzymes that release fat from the cells. to avoid this “starvation mode” use exercise to BURN THE FAT, not very low calorie crash diets.
  2. Get control of your weight now.
    If you are gaining weight, and especially if your weight is climbing upwards out of control, make a decision to STOP RIGHT NOW.
    Your fat cells are expanding and may make it more difficult to burn fat in the future. NOW is the time!
  3. If you’ve already lost weight, you must be forever diligent.
    Your fat cells are not gone, they have merely “shrunk” or “emptied out.
    Fitness is not a 12 week program, its a lifestyle.
    To stay lean you have to eat right and stay active
  4. Genetics are only a minor factor.
    You may not have control over how many fat cells you were born with, but you do control the major factors that determine how much fat you store: lifestyle, exercise, nutrition, mental attitude.