Here’s a puzzler that stumps many people: when you lose weight on a diet, where does it go? That five pounds you’re proud of shedding, where is it now? What’s it doing and could it be causing any harm, such as to the climate?
The question isn’t as crazy as it may sound, although thankfully there is a reassuring answer.
The weight can’t just vanish into thin air…or can it? The answer is surprising even for health professionals. A recent survey suggested that more than 90% of doctors and even dieticians couldn’t explain what happens to all that fat they advise us to lose.
Most people can make some intelligent suggestions.
For example, the idea that the fat is converted into energy seems plausible but it isn’t the answer.
Or how about it’s turned into muscle? No that doesn’t work either. Muscle requires protein and a host of other nutrients that fat just can’t provide.
Others suggest it’s flushed down the toilet as part of normal bodily functions but that’s not it either.
So where does it go? Well, the simple answer is that we breathe most of it out as carbon dioxide and the rest is turned into water, which is evaporated as sweat or excreted when we go to the loo.
The connection between unwanted fat and the way we breathe may seem unlikely but here’s how it works as described by Australian biomolecular scientists, Ruben Meerman and Professor Andrew Brown.
If you lose 10 pounds of fat, 8.4 is converted into carbon dioxide and breathed out through the lungs. The other 1.6 is turned into water.
Does all this carbon dioxide we’re breathing out mean we could be contributing to global warming and climate change?
After all, the average person breathes out about 500 litres of carbon dioxide every day, and that doesn’t include the extra if you’re burning extra fat to lose weight. You don’t need to be a scientist to realise that with nearly seven billion people on the planet, that’s a lot the global warming gas going into the atmosphere.
So could those dough nuts and cream cakes we’re burning off be contributing to climate change. Thankfully, no.
No matter how much CO2 we breathe out we’re not adding any extra to the atmosphere. This is because the CO2 we exhale is part of a natural cycle in which we eat food from plants that store carbon. We turn that food into energy, water and carbon dioxide.
As we need to continue eating, we grow more plants that in turn absorb carbon dioxide and cancel out the amounts we breathe out. In this way, an equilibrium is reached and should be maintained, as long as we stick to our normal food and don’t start nibbling lumps of coal or sipping crude oil cocktails. Not very likely.
This process of breathing out CO2 doesn’t just cover weight loss. Nearly everything we eat and drink, including alcohol, is converted into carbon dioxide and water. The only significant exception is dietary fibre such as corn and grains, which remain largely undigested and proceed to the colon.
That fibre is essential to keep our digestive systems healthy, which is why doctors and dieticians urge us to include some in our diet every day.