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Where does body fat go when we lose weight? The answer is stranger than you expect

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Cite

Chihi, C. (2026, October 1). Where does body fat go when we lose weight? The answer is stranger than you expect. Euronews. https://www.euronews.com/2026/10/01/where-does-body-fat-go-when-we-lose-weight-the-answer-is-stranger-than-you-expect

Dated when The Aporia collected the article, usually within hours of publication. Check the original for its exact date and byline.

Euronews · collected 2026-10-01 · by Chaima Chihi

Quick Summary

Researchers from the University of Birmingham explain in The Conversation that when people lose weight, approximately 84% of lost body fat is exhaled as carbon dioxide, with the remaining 16% leaving the body as water. This process occurs when the body enters a calorie deficit and uses stored fat for energy; during this metabolic breakdown, fatty acids are converted into compounds used to produce energy, resulting in carbon dioxide and water as by-products.
Written by AI on 2026-10-01, from this article's own text only (the story summary below draws on all the coverage).

AI analysis

Story summary

Two researchers from the University of Birmingham explain in an article published in The Conversation that when the body needs more energy than it gets from food, it taps into its fat reserves. They estimate that around 84% of lost body fat is exhaled as carbon dioxide, while the remaining 16% is lost through water. Fat storage occurs primarily in two forms: subcutaneous fat, found just under the skin, and visceral fat, which accumulates deeper inside the body around organs. When the body enters a calorie deficit, it triggers lipolysis, breaking down stored fat into fatty acids that are then converted into energy or exhaled as carbon dioxide.

Written for “Body Fat Weight Loss Mystery” on 2026-11-03, grounded in this article and the 0 other(s) covering the same event.

Story

📰 Body Fat Weight Loss Mystery
Science · 1 article(s) covering the same event.

Compared with similar articles

Nothing to compare against. No article is close enough to this one for the pipeline to have linked or judged the pair.
How this article was measured signals, leaning charts, publisher record, byline, topics and claims

Signals How these are calculated →

Claims extracted
18
sentences that state something as happening or true
Uncertain
6%
1 of 18 hedged ("reportedly", "may", "according to")
Leaning
not political
takes no side on a contested political question
Publisher signals
60/100
Euronews's corrections and hedging, across everything collected from it. Not a measure of accuracy.
Outlets on this story
1
Science
Same framing elsewhere
1
articles that frame the event the way this one does
Analyzed 2026-10-01 · how these are computed

How this is being covered How these are calculated →

Article leaning vs. publisher reliability
Source leaning vs. consistency

Publisher

Euronews · 1162 article(s) · 1 correction(s) detected
Running correction rate · 1 correction(s)

Who wrote this

Chaima Chihi
4 article(s) here · 0 carrying a prediction
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Also by Chaima Chihi
Nothing else under this byline is closely related to this article, so these are simply their most recent.

Topics

The Conversation the University of Birmingham

Subjects

The Conversation ORG · 1× the University of Birmingham ORG · 1×

Narrative

Two researchers from the University of Birmingham explain in an article published in The Conversation that fat loss is linked to a process that begins when the body needs more energy than it gets from food, so it turns to its fat reserves to meet that need.
framing: assertive · carried by 1 article(s) · first seen 2026-10-01

Claims (18 extracted, 1 hedged)

Researchers estimate that around 84% of lost body fat is exhaled as carbon dioxide, while the remaining 16% is lost as water. asserted
% → estimate → water
When body weight falls, some of the fat stored by the body disappears – but where does that mass actually go? asserted
mass → fall → body
Two researchers from the University of Birmingham explain in an article published in The Conversation that fat loss is linked to a process that begins when the body needs more energy than it gets from food, so it turns to its fat reserves to meet that need. asserted
it → explain → need
The fat we eat reaches the digestive system, where it is broken down into fatty acids. asserted
it → eat → acids
The body uses part of these fatty acids for essential functions such as building cells, regulating hormones and protecting organs, while the surplus is converted into triglycerides that are stored inside fat cells to be used later as an energy source. asserted
that → use → source
The body mainly stores fat in two ways: subcutaneous fat found just under the skin, and visceral fat that builds up deeper inside the body around the organs. asserted
that → store → organs
When the body enters a state of calorie deficit, hormonal and neural signals start to stimulate fat cells to break down stored fat, in a process known as lipolysis. asserted
signals → enter → lipolysis
Fat is converted into energy asserted
Fat → convert → energy
After triglycerides are broken down, fatty acids travel to the mitochondria inside cells, known as the body's "power stations", where they undergo beta-oxidation. asserted
they → break → oxidation
During this process, fatty acids are broken down into compounds the body uses to produce energy, and these reactions generate carbon dioxide and water as the final by-products of metabolism. asserted
reactions → break → metabolism
And here lies the surprise, according to the article: most of the fat the body loses does not leave through sweat, but through the lungs while we breathe. uncertain
we → lie → lungs
Based on the researchers' calculations, around 84% of lost fat is turned into carbon dioxide and leaves the body when we exhale, while about 16% becomes water that is eliminated through sweat and other bodily fluids. asserted
that → base → sweat
The researchers note that these percentages remain estimates, as it is difficult to measure all of the body's outputs precisely during fat loss. asserted
it → note → loss
What does this mean for exercise? asserted
this → mean → exercise
When people exercise or cut their calorie intake, the body's need for energy rises. asserted
need → exercise → energy
If the energy supplied by food is not enough to cover this demand, the body starts using its fat stores. But this does not mean that breathing rapidly causes fat loss. asserted
breathing → supply → loss
Exhaling is the route through which the products of fat burning leave the body, not the process that triggers fat burning itself. asserted
that → leave → burning
Maintaining a calorie deficit, through diet and physical activity, remains the key factor that pushes the body to tap into its stored energy. asserted
that → maintain → energy
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