Where Does Fat Go When We Lose Weight?
I had a follower send me a graphic the other day that talked about the ‘Big Whoosh.’
Never in all of the science classes I’ve taken and in all of the years I’ve been practicing as a dietitian, have I ever heard of a ‘Big Whoosh.’ Turns out, the person who posted the graphic -a ‘health coach’ – said that’s what happens to fat cells when we lose weight. Of course, she was selling a product.
Another person on the internet who shall remain unnamed, floated the claim that the ‘Whoosh Effect’ – which is different than the ‘Big Whoosh’ – happens when we lose weight.
This person said that after the fat cells release fat, they temporarily fill with water, making you feel ‘squishy.’ She said that this water retention occurs because ‘the fat cells are hoping to fill up again with fat.’
Sort of, keeping the bed warm for their friend, I guess.
Apparently, this person doesn’t science. Because despite her compelling description, she’s absolutely wrong:
Our fat cells don’t fill with water after they release triglycerides during weight loss. They just sort of…sit there.
But what DOES happen to fat when we lose weight? Where does the it go? And maybe there isn’t a ‘Big Whoosh,’ but do fat cells disappear or leave the body when they’re empty?
All very good questions, and all about to be answered in this post.
Spoiler: people saying things like, ‘Big Whoosh’ or ‘Whoosh Effect’ should be ignored. But you knew that already.
What are fat cells?
Contrary to popular belief, we aren’t born with all of our fat cells. We accumulate them – at least what’s determined to be our baseline number – until well into our teens.
Most of the fat in our bodies is what we refer to as white fat, or WAT (white adipose tissue). White fat stores triglycerides for energy, cushions our organs, keeps us warm, and produces hormones.
When we eat fat, it gets broken down and metabolized by the liver into triglycerides. These are stored in the fat cells, liver, and to a small extent, in muscle. When your body needs energy, it releases the triglycerides into the bloodstream in a process called lipolysis.
The body tries to maintain a balance of ‘lipid turnover,’ which is the name given for the process of storing and removing triglycerides in fat cells for energy. Of course, if you go into calorie deficit, this balance tips, and you lose weight.
Recent research measuring lipid turnover rates suggests showed that lipid removal slows as we age – basically, our cells continue to take up fat, without losing as much of it. That may make it harder to lose weight as we get older.
If we eat too much of any macronutrient, it’s converted into fat and stored in fat cells. Out of fat, carbs, and protein, fat is the easiest for the fat cells to hoard, because it’s already in the correct form.
But that doesn’t mean that carbs and protein can’t find their way into fat cells.
It’s not as easy for the body to do that, but yes: if you eat too much protein, it’s eventually going to be stored as fat.
I know there’s a school of thought that protein is stored as itself and not as fat, but nope.
That’s just a myth.
When the fat cells you already have fill up and can’t hold any more fat, new fat cells can grow.
I feel like we need a ‘bloop!’ sound effect here. Is it just me?
I also feel the need to clarify that fat cells, like any other cells in our bodies, don’t turn into other cells. For all of those people who swear that not exercising for a long time will turn your muscle into fat, that’s never going to happen.
Fat cells. Muscle cells. Different things.
When fat cells die, they very quickly get replaced by new ones. That’s because the body likes homeostasis, otherwise known as ‘keeping things the way they are.’
In other words, our fat cells don’t go away. Ever.
Not unless they’re surgically removed via liposuction, or another procedure.
White vs brown fat.
You may have heard about white and brown fat, and how it’s better for us to have more brown fat. Brown fat has been shown to be metabolically active – aka it actually burns calories – versus white fat, which just sort of sits there.
We’re all born with white and brown fat, but as we grow out of infancy, our brown fat all but disappears. We retain a very small amount of it into adulthood – like ounces, versus pounds of the white stuff.
Brown fat is brown because its mitochondria (essentially, the powerhouse of the cell) contain iron.
Brown fat is more active in cold conditions, which is why a while back, you may have seen some media articles making recommendations to turn your thermostat down in your house.
Being in the cold for prolonged periods of time also seems to increase brown fat cells in our bodies.
There have been plenty of studies around how to get humans to gain more brown fat to help them lose weight and protect them from metabolic disease. The problem is that many of these have been mouse studies, which don’t really translate into humans. Mice have more brown fat than we do, and we aren’t rodents.
A 2015 study suggested that a common medication used for overactive bladder, may help increase the amount of brown fat in humans. Another study by the same team, with the same medication, and the same findings, was released in 2020.
As it stands, there aren’t any official recommendations around how to increase brown fat. You could lower the heat in your house, or go outside in the winter without a coat, but nobody is really sure how much good that does.
So…What happens to fat when we lose weight?
Let’s clarify something right off the bat. We lose fat the same way we gain it: in fractions of ounces at a time, not by pounds. Just like you won’t wake up the morning after a huge meal with 5 pounds of new fat gain, you won’t drop pounds of fat at a time.
Weight loss can be quick, generally when you have a lot of weight to lose – but for most of us, true fat loss (versus water) is an incremental process.
When we lose fat, we literally breathe it out. Yup! The fat in our bodies is converted to water and carbon dioxide, and expelled by the lungs and in our pee (the water part, that is).
As the fat leaves our fat cells, these cells get smaller. But they don’t disappear completely, even when you lose weight. They stand by if and when they need to get bigger again.
They’re like balloons, except they fill up with fat instead of air. Deflate, inflate. Deflate, inflate.
You get the point.
For all of you who are trying to lose weight.
Some of you will read this post because you’re looking for help with weight loss. I get it.
But as I said before, people who try to sell you false information and claims are not who you should be looking to for nutrition advice.
Losing weight is tough, and it can be very complex. It’s truly often a mix of physical and emotional challenges that are best left to a professional who is able to navigate these things. Not an MLM coach, someone on Instagram, or a person who doesn’t have credible nutrition and counselling experience.
Another option is my book Good Food, Bad Diet, which teaches you how to get out of the diet mindset altogether. If you’ve been going around and around with diets and a negative relationship with food and your body, my book can help.