Category Archives: Fitness

Why you can’t believe weight loss testimonials

I wrote yonks ago about why you can’t always beleve the hype about fitness fads, and encouraging people to think critically before buying in to anything. At this time of year a lot of people are making themselves promises about the way they look, so when I stumbled across a short blog post this evening, I thought it was worth sharing.

The post illustrates exactly how easy it is to fool the eye (and the wishfully-thinking brain) with just a little work on posture, flexing the right muscles, using good lighting and a touch of post-production work. Just take a look at the panel below – all of the images in it were taken within the space of an hour. With a few changes of outfit and a quick shave, the author was able to take a series of photos that any fitness “guru” would be proud to use as a before/during/after montage (click on the image to view a bigger version, click here to read the blog post in full).

So what’s my point? When it comes to fitness, don’t believe your eyes. Don’t part with your hard-earned cash on the basis of a flashy web page and a few beguiling words. The best way to assess these things is to find someone who knows what they’re talking about, and talk to them about it – social media is a great way to do this, as it gives you access to thousands of experts almost instantly. I’d be happy to help you start – just leave a comment or send me a tweet.

So you think you do Tabata?

I just found this post, fully-formed, in my drafts folder. I wrote it in April, which shows just how badly I’ve neglected this blog. Sorry about that, but to tide you over, have a little post on fitness. This post is shamelessly stolen from myself, from a totally different blog.  I’m re-posting it here because I think it makes points about critical thinking and evidence that fit with this blog’s ethos pretty well, and also carry on the theme of questioning what you’re told about health and fitness that I started a few weeks ago.  Without any further hesitation, here’s what to bear in mind when you hear the word “Tabata”…

I have a bugbear. I’m going to use it to hopefully produce a blog post that’s useful and informative, but first I’m going to get something off my chest.

If you work out regularly, or even if you don’t, the chances are you’ve heard of the Tabata protocol.  Named after Izumi Tabata, the chap who first published an academic journal on the subject, the protocol is very simple:

  1. 20 seconds of work, immediately followed by 10 seconds of rest
  2. performed 8 times without any pauses or interruptions, for a total of 4 minutes
  3. with the working phases performed at 170% of VO2max

If you deviate from this on any point, you’re not doing Tabata, you’re doing interval training.  You may even be doing High Intensity Interval Training (HIIT), but it’s still not Tabata.  Does it matter? Well, yes.  Just because you’re doing intervals on a 20:10 split doesn’t mean you’re working to the same intensity as the Tabata protocol, and that means you can’t necessarily expect to get the results of the Tabata protocol.  As an example, depending how hard you’re working it’s a little bit like the difference between doing a class like Body Pump, and training with Olympic weightlifting; both might make you sore the next day, and help you get stronger, but it’s evident that in the long-term, and arguably the short- and medium-term too, the results are very different.

That’s my pet peeve (more-or-less) off my chest, so on to the useful part.  Points one and two on the list above seem straightforward, but what’s VO2max?

Simply put, it’s the maximum volume of oxygen that your body is capable of using. It’s usually expressed in litres per minute (L/min), or in millilitres per kilogram of bodyweight per minute (mL/kg/min). Men generally have a higher VO2max than women, and it tends to increase as you get fitter (and also decrease as you get older).

The next obvious question is, if VO2max is the maximum volume of oxygen your body can use, how can you reach more than 100% of it? That’s because your body has two energy systems.  Let me expand

  • The aerobic energy system uses oxygen to produce energy. It uses glucose, which goes through a series of chemical reactions to produce energy molecules like ATP, with CO2 and water as the waste products, and a few other things that are important to your body (but not to this blog post).
  • The anaerobic system can produce energy in the absence of oxygen, by using up molecules like ATP, and by breaking down glucose and glycogen in the absence of oxygen.  This produces by-products like lactic acid.  Once you’re at rest, your body will use some of the oxygen it’s consuming to metabolise these by-products and return your muscles to peak condition.  This is sometimes referred to as the “oxygen debt”, because you’re paying back oxygen for energy you’ve already used.

What this means for you is that you can work at a rate that is higher than your VO2max; your aerobic system will consume as much oxygen as it can, and your anaerobic systems will also kick in, but you’ll have an oxygen debt to pay off once you’re finished.  Back in the 1990s Tabata decided to test what effect using both of these systems at once would have on fitness, so he took the now-familiar 20:10 protocol (which was already being used by the Japanese speed skating team in training) and compared it to steady-state cardio.

A summary of the results is available for anyone to read if they want to, but the gist of it is this:

  1. The study was quite small, with a total of 23 men who were already physically active – no women were tested. Only 7 men completed the interval training experiment.  All athletes trained 5 times per week in total.
  2. Athletes performing cardiovascular exercise at steady state (70% of VO2max) for an hour significantly improved their VO2 max.
  3. Athletes performing intervals of 20 seconds of work at 170% VO2max interspersed with 10 seconds rest (with one 30 minute session per week at steady-state 70% VO2max) increased their VO2 max by a similar amount to the other group, but also increased their anaerobic capacity by 28%. In reality this group performed 7-8 sets of high-intensity work in each session; the session was terminated if their pedalling speed dropped below 85RPM.  If they were able to do 9 sets, the difficulty was increased the next time. This means that the workout was always varying, and it’s likely both that no two men ever did the same workout, and that no man ever did an identical workout more than a few times.

One really important point to take away from all of this is that working at 170% of your VO2 max is hard.  Really hard.  Joe Bloggs can’t do it, at least not without falling over or being sick (or both). It takes a trained athlete, someone who pushes their limits most days to achieve this kind of intensity. And since this is the only protocol that was tested, this is the only protocol that we can make claims about.  Even them the claims aren’t particularly strong if you look at this trial in isolation – the results for seven men who were already quite fit aren’t likely to generalise very well to a larger population of diverse individuals. Crucially, if you work at less than 100% VO2max (which most people will), you certainly shouldn’t expect anaerobic benefits of this magnitude, if any.

So what was my point again?  A large part of this is my belief that language should be used accurately – call a spade a spade.  The Tabata protocol is a very specific thing, which has been found to produce very specific results.  Calling your workout Tabata when it’s not is at best pointless, and at worst misleading (or, if you’re a fitpro selling your services, false advertising).

There’s no doubt that doing almost any form of HIIT is beneficial  (and I don’t mean to discourage it), so please don’t stop doing it, but – to keep me sane – please do stop calling it Tabata?  Cheers 😉

Should you believe the fitness hype?

I see this over and over again among otherwise very intelligent people; an odd belief that the latest “big” thing in exercise or weight loss will be a magic bullet that suddenly brings them the body they’ve always thought they should have. Zaggora hot pants (Burn more calories!), Skechers Shape Ups (reduce cellulite!), green coffee extract (100% natural!) – the list is basically endless. Leaving aside the notion that this will somehow make them happy (for I haven’t the knowledge or skills to even begin to tackle that), why do these bright people fall for it?  I can’t answer that either. It’s potentially very harmful though – this tweet from @nchawkes says it rather well:

People end up spending frightening amounts of time, money and energy on these promises, and even when there’s temporary success (often due to diving into a new regime with a positive opinion, in my totally-un-evidence-based opinion) ultimately there’s stagnation at best, failure or regression at worst. These things are hugely destructive to body image and overall self-image.

So if I can’t explain the fascination with these things, the least I can do is provide a small extra weapon in the battle against profiteering and misinformation in the fitness world.  (Aside: it’s worth noting that much of the misinformation is spread amongst well-meaning friends, just trying to help one another; this type is just as difficult to address as any other dearly-held belief).

My first pearl of wisdom is hardly novel: anything that seems too good to be true, is. The cold hard truth is that you can’t permanently change your body without permanently changing your diet and lifestyle; they needn’t be massive, life-altering changes, but they must happen. You also can’t permanently change your body by throwing money at it instead of good quality food and exercise (unless we’re talking surgery; that’s pretty permanent).

My second piece of advice is: apply critical thinking. Is there something you’re naturally skeptical about, or distrustful of? Apply that same level of suspicion to diet and lifestyle advice. New device guarantees weight loss in one workout? Great. What’s the mechanism? Does it seem plausible? Is it more likely that it’s just helping dehydrate slightly, thereby losing water via sweat? Never ever forget that water’s heavy; 1kg (2.2lb) per litre to be precise. Doubt everything. 

Thirdly, and maybe most importantly (and predictably), demand evidence. Good quality evidence at that. Be ruthless. Be picky. Crucially, don’t accept anecdotes. These are everywhere in weight loss fads, to the point that I feel they’re worthy of a specially-adapted version of the anecdote rules:

  • Did the person gain the advertised benefit, and maintain it?
  • Was the advocated treatment the only one used?
  • If it’s really so good, why aren’t doctors and fitness professionals everywhere advocating it?

I’m hoping to look at some individual claims in more detail, but hopefully this post will at least serve as a cue to get you thinking about the way you look at claims in the weight-loss industry.