Spot Reduction Works...Sort Of
It’s been a long time since I’ve gotten a significant number of questions about spot reduction. Spot reduction is basically when you train a specific muscle or muscle group with the intention of burning the fat in the area around the muscles. The fact that this approach doesn’t work has been well-known for so long that it has almost completely seeped into our cultural consciousness. Only those completely unfamiliar with exercise science still believe it’s possible to burn fat locally.
Nevertheless, sometimes researchers like to think outside the box to further isolate variables in any topic. Spot reduction is no exception, and recently in a study published in the Journal of Strength and Conditioning, researchers decided to give it another look. Maybe after all this time it’s finally possible. Might as well look, anyway.
Despite the fact that most people consider it a false theory, there are some reasons to think spot reduction could work. Fat is burned locally in the body but sourced globally. This means that fat moves through the blood, so it comes from everywhere in your body to be utilized wherever it's needed. There’s nothing special about the location fat comes from, or at least that’s what we’ve thought now for many years. However, even simple factors like differences in body temperature can affect blood flow, which is the means by which fat is carried. Perhaps there are other ways in which the location that fat is sourced for fuel can vary from body part to body part.
The researchers used a normal study method, and then took it to an extreme. They had the participants use a leg press with only one leg. This is done sometimes in studies so that the unused leg becomes the control that the protocol is compared against. The participants used that one leg a lot - and by that I mean they did somewhere in the neighborhood of 1000 rep sets, three times per week for twelve weeks. It reminds me of that episode of The Simpsons where Homer did bicep curls all day, every day with just one arm.
At the end of the twelve weeks, the researchers measured the body fat, lean mass, and other data for several body parts and for the whole body. Sure enough, fat was reduced significantly in one part of the body and not another part, which makes it seem like spot reduction works. Here's the bizarre part, though. You're probably assuming that fat was lost in the trained leg, but it wasn't. In fact, the untrained leg wasn't even the area of most fat loss. The most fat was lost in the upper body, but not significantly in either of the legs.
There were a few proposed explanations. The first is that more fat is carried in general in the trunk, and so more fat would be lost from that area. The second explanation was that enzyme activity in the arms makes them better able to mobilize fat for fuel, even for the lower body. Whatever the reason, the results were certainly not what you’d expect.
So there you have it. You can kind of spot reduce, but only for the upper body, even if all you work is one of your legs for 1000 rep sets. It's a bizarre study with an even more bizarre conclusion, but now you know.
1. Ramírez-Campillo, Rodrigo, et. al., “Regional Fat Changes Induced by Localized Muscle Endurance Resistance Training,” Journal of Strength & Conditioning Research, 27:8 (2013).
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