I know what you’re thinking…UGH! CHEMISTRY! EWWWW!!!

Wait! Don’t go! Come back! I promise this will tell you everything you need to know about how you actually lose fat. Minimal science guaranteed!

Ok, so that big long thing at the beginning of the equation is the esterified form of an “average” triglyceride, otherwise known as the fat you store in your adipocytes (yikes, fat cells). That’s fat being stored in all the places you don’t want it. Now take a look at the second part of the equation, particularly at the conveniently highlighted CO2 and H2O, simply carbon dioxide and water (plus the associated energy that comes from the chemical breakdown of a fatty acid). This means that once a fatty acid gets broken down, it gets released as carbon dioxide (when you exhale) and water (sweat, bathroom happenings, etc). 

So inevitably, you end up breathing out your fat. Crazy science. 

In an article published in the British Medical Journal, Ruben Meerman and Andrew J. Brown (found here) took this equation further, finding that 84% of fat is eliminated from the body as CO2, and a mere 16% from water. This, of course, lays credence to the vast evidence demonstrating that endurance, cardiovascular-based activity like running or jogging would be an efficient way to go about trimming off fat. Side Bar: It would be amazing to see the impact of interval training on this idea since technical HIIT work is entirely anaerobic, meaning it operates without the presence of oxygen and intervals are typically shorter with a fair amount of recovery. One step further would be to compare HIIT workouts vs endurance intervals (like in a Tabata set, :20 work/:10 rest for 8 sets). 

Before you go spouting off about the invaluable benefits of cardio, the point is not to tout the benefits of cardio for fat-burning, but to show how much a poor dietary intake is easily the biggest detriment to dropping unwanted fat from the body. Testing an average-sized person of 154 lbs, it was found that with a normal schedule, involving sleeping, eating, and light daily activities, a person would exhale roughly 203 g of carbon from the body during a day. Adding in an hour of cardio would eliminate about 39 g more carbon, which adds about 20% to the total (score!). Add in 100g muffin though, and that takes off 20% of an individual’s total daily energy requirement. That’s 20% of what should be ingested in a 3.5 ounce muffin. 1 muffin. 

The idea that you “can’t outwork a bad diet” never rang so true, and this study really elaborates on how sensitive our bodies are to the food choices that we make. 


Meerman, R. and Brown, A.J. BMJ 2014;349:g7257