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[Michael] If you spend time on the internet, you probably see a lot of ads.  After a while, you might notice that some ads show up everywhere.  Like you've probably seen something along the lines of this one: "Lost weight with this one weird old trick!  Doctors hate this!"

It turns out that those kinds of ads are really old, like older than the Internet even.  As far back as the 19th century, companies were advertising all sorts of strange ways to shed fat.  And from so-called sauna pants to electric shockers to vibrating belts, you'll sometimes still see them presented as a way to lose weight.

They make tempting promises - just stand around, let the machine do the exercising for you!  But these methods aren't exactly effective because the supposed science behind them isn't quite so scientific.

Take the sauna pants, for example.  The idea was that you'd make some part of your body really really hot, sweat a lot, and somehow get skinnier in the process.  But all you were doing was dehydrating yourself.  

There were a lot of different versions.  Some advertised in the 1970s were like giant inflatable balloons for your body.  Others were heated electrically and, for some reason, you can still buy them though they aren't generally marketed for weight loss anymore.

If you've ever imagined pants made out of an inflatable mattress, you can probably imagine that it was indeed REALLY hot in there.  You would sweat a lot.  And of course if you weighed yourself before and after you tried this, the numbers would totally go down on the scale.  

According to the ads, this meant that you were losing what they called water weight, which is technically true.  Wearers of the pants lost some weight through sweat, and sweat is mostly water.  

But that's essentially the same thing as saying that peeing is an effective weight loss method, which...no!  Unless you plan on staying dehydrated forever, it comes right back the next time you drink.

Electric shocks were also once all the rage, and you'll still see these electronic muscle stimulation or EMS devices for sale, claiming to give you rock hard abs or whatever.

But while they might be able to make your muscles firmer, they aren't going to burn much fat.  Normally, signals from your nerves releases lots of charged ions in your muscles, making them contract.  So when you apply an electric charge with an EMS machine, those muscles think your nerves are sending them a signal, and they contract like crazy.  

And that does exercise your muscles, which have to use energy as they contract and then relax.  And in some cases, the repeated contractions have been shown to make them firmer over time.  

But since it's just a few individual muscles moving, instead of your whole body working together, they don't use very much energy.

One study found that a 75 kilogram person using an EMS device for an hour might be able to burn 76 calories total, but if that person decided to walk around for an hour, they would've burned 326 calories.

Which is why, at least in the U.S., the FDA won't approve any EMS device that claims to help with weight loss.  And even the approved versions can cause burns, so you might just be better off doing your crunches manually.

And now we come to the fat jiggling belts.  They promise to loosen fat, which your body would just flush away, though no one ever explained exactly how.  And that's not how fat works.  You might be able to shake it off, but only because you're burning off fat as you shake and definitely not if something else is doing the shaking for you.

Movement takes energy, and normally when you exercise that comes from the energy stored in your cells.  Eventually your body starts breaking down the chemical bonds and fat molecules to get that energy.

But in the case of fat jiggling machines, the energy was coming from the electricity powering the machine, not your fat cells.  There are ways to make your body "flush away fat" like a cosmetic procedure that kills fat cells by freezing them.  And other body-shaking techniques like chairs that swivel back and forth while you sit on them work by forcing your muscles to compensate for the movements.

But you can't just detach your fat cells by moving them around a little bit.  Exercise only burns fat if your body is breaking it down for energy.  So if that's a thing you want to do, you're gonna have to put in the work yourself.

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