Saturday, October 19, 2013

The Fallacy of Working Out To "Burn Calories" + Exercise Shuts Down the Carb Cravings: Bench Press, Leg Press HIIT & LISS Are Not Meant to Incinerate the Junk You Eat

If you work out to be able to allow yourself to eat, you know you have a serious problem.
So, what was that about the bench pressing consuming as much energy as leg presses and the "exercise just makes you hungry myth" on the last installment of the Science Round-Up? If that's what you have been asking yourself this morning, when you showered I am impressed - or should I be worried?
If you have not done so already, this would be the right time to download + listen to the Science Round-Up - I promise there is much to learn and not all of it is going to be repeated here.
Whatever... in the end it does not matter how urgent you were waiting to take a look at the data that supports my argument that (a) exercise does not just make you hungry, and that (b) the notion to work out primarily to burn energy is hilarious.

Chest vs. legs what's energetically more costly?

While I could imagine that the comparison would have yielded a different result if the 10 healthy young men (>1 year of resistance training experience; BMI ~24kg/m²) had performed squats instead of regular leg presses, I have to admit that I was still surprised to see that Magossoa et al. actually found no difference in the total energy expenditure between 3 sets of 10 reps (70% 1RM) of bench vs. leg presses (Note: The researchers determined the total energy expenditure using the oxygen uptake (aerobic component) the EPOC and lactate production (anaerobic component)).
Table 1: Workload, energy expenditure total, per minute per weight lifted (Magosso. 2013)
If you look at the data in Table 1, you will have to concede: The only difference between the energy expenditure during the leg and the leg press was the inferior energy consumption per kg of weight on 'the bench'.

If you were one of the lazy (and mostly ignorant) buggers who "already have big enough legs", you could probably use these results to argue that leg presses and the rest of the leg workout was a pretty unnecessary undertaking - I mean, if you don't want bigger legs it should at least help you with that sixpack by burning a couple of calories, right?

Only a fool will work out to "burn energy"

Suggested Read: "Busting the 3,500kcal = 1lbs Weight Loss Myth! Debunking the rule of thumb with the power of science" | read more
Once they're there, it does usually you not take very long until people will remember this ingeniously simply (and about s flawed) rule of thumb that says: To lose 1lbs of fat you got to burn 3,5000kcal. Here, in our concrete example, that would mean that it would not matter if you did another 228 sets of bench presses or leg presses to lose 1lbs of pure body fat.

Once you've gotten caught in calculations such as the above, i.e. 229 sets x 46kcal / 3 sets  > 3500kcal, or in words "I got to do 228 sets of bench presses to burn one pound of body fat!", you are lost.

Firstly, the equation 3,500kcal caloric deficit = 1lbs fat loss if flawed (learn more).

Secondly, and even more importantly, doing more, which is what all the "I workout to lose fat" weekend warriors do, is not going to yield superior results. If you don't believe that, I suggest you go back to my "How to Burn 27,300 Kcal Extra W/out Losing a Single Extra Pound of Fat!"-article and take a look at the results of the Rosenkild study from 2012 (figure 3).

Gary is ... no, not a fool, but he is still wrong

Now, I obviously cannot forbid workout extra and luckily even Gary Taubes can't because even if you insisted to burn 600kcal, instead of just 300kcal, you can at least console yourself that this is not going to increase your appetite (learn more). Especially if we are talking about relatively intense exercise for similarly "relatively obese" individuals, working out will not only reduce your window of opportunity to eat (for some people even that may make a difference, believe me), but rather work like a gastric bypass - one that won't allow you to hit your obesogenic macros on the subsequent meals.
Figure 1: Macronutrient intake (lunch + dinner in g) on control vs. exercise day (David. 2013)
Those of you who have not listened to the podcast yet will now probably be wondering what I am talking about, right? Well, take a look at the 3D bars in Figure 1. They represent the results of a study David et al. conducted earlier this year. A study that involved both lean and obese kids and a study that demonstrates that a relatively short (3x10 min) but comparably hard workout (75% VO2max) is not going to make the sugar junkies crave for more - quite the opposite, it will reduce their apperite for carb(age) to a normal level [similar appetite-reducing effect were observed by Sim et al. (2013) in adult men and Rosenkilde (2013; already discussed at the SuppVersity].

I mean, a voluntary 35% reduction in carbohydrate intake during lunch and dinner and a total reduction in energy intake of 475kcal are impressive ballpark figures considering the fact that exercise is often said to "just make you hungry" - wouldn't you agree?

EPOC should not determine your choice of exercise either

If you are sprinting because of the increase in EPOC, you are a fool.
From the article I referenced in yesterday's write-up ("More Than 3x Higher EPOC Induced Energy Expenditure With HIIT vs. LISS! But Does That Really Matter?" | read more) you already know that  HIITing it hard on Wingate tests will yield a pretty pathetic increase in EPOC of ~20kcal over a casual 30min jog.

So even if it was about burning calories the jog would be far superior because the increase in Excess Post-Exercise Oxygen Consumption (EPOC) is not going to compensate the additional kcal the subjects in the Townsend study burned during the steady state exercise.

The latter is by the way not much different if you compare two different HIIT regimen - a very intense short one (HIIT1) and a somewhat longer slightly less intense alternative regimen (HIIT2):
  • HIIT1: 10 x 1min, 1min pause between intervals; cycling at 80-90RPM at 90% of the HRmax
  • HIIT2: 10 x 4min, 2min pause; cycling at 60-80RPM and without a prescribed minimal heart rate
In their trial that involved 9 lean, healthy male subjects, Kelly et al. obeserved that the HIIT2 trial was more than two times more energetically costly (675kcal vs. 275kcal) - the EPOC effect on the other hand did not lead to any significant differences in post-exercise energy expenditure, so that the HIIT1 group was stuck with their ~400kcal inferior energy expenditure... now, that sounds as if it was a bad thing, but if we consider that they spent less time on the ergometer and were rewarded with a greater stimulus for mitochondrial expansion and even muscle growth (see "The Anablic Effects of HIIT" | read more), I would not say that they came off second best - would you?
Practical suggestions for your workout week...
  • health focus - 2-3x resistance training + daily LISS as in walking (min. 30-60min)
  • performance focus - 3x resistance training + 1-2x HIIT + 6x LISS as in walking (30-40min)
  • physique focus - 3-4x resistance training + 1x HIIT +  6x LISS as in walking (30-40min)
Don't forget that the reason you do the LISS training is not because you want to burn calories, but rather because you want to spend some time doing what you actually would have to do everyday: Walking from place A to B; and if you belong to the few of us who don't sit on a desk all day, you may skip the walk in the park.
So what's a good reason to work out, then? Health! I know that does not sound as sexy as six-pack abs and bigger sleeves, but there is not denying it: Exercise is your vaccine and magic pill. It's what's going to make you feel good, look good and age well and unless you want to end up debilitated in a nursing home it is not optional even if you follow an energy restricted diet for the rest of your life. What is optional, though, is exercise as a means to increase athletic performance or influence the shape of you body withing your individual very specific limits.

Within this health ↔ performance ↔ looks triangle you will often encounter conflicts, where the optimization of one compromises the realization of another. I am nevertheless convinced that classic light intensity steady state (to make up for our modern sedentary lifestyle), en vogue high intensity interval training (to increase your VO2max) and classic and modern forms of resistance training (to build and maintain muscle mass) all have their place in a routine that does not lose sight of any of the vertices of the triangle.

What? How you can ever lose weight without doing endless hours of cardio? Well what about dieting?
  • David T, et al. Obese but not lean adolescents spontaneously decrease energy intake after intensive exercise. Physiol Behav. 2013 [epub ahead of print]
  • Kelly B, King JA, Goerlach J, Nimmo MA. The impact of high-intensity intermittent exercise on resting metabolic rate in healthy males. Eur J Appl Physiol. 2013 Oct 6. [Epub ahead of print]
  • Magosso et al. Energy Expenditure during Multiple Sets of Leg Press and Bench Press. Journal of Exercise Physiology online. October 2013.
  • Rosenkilde M, Auerbach P, Reichkendler MH, Ploug T, Stallknecht BM, Sjödin A. Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise--a randomized controlled trial in overweight sedentary males. Am J Physiol Regul Integr Comp Physiol. 2012 Sep 15;303(6):R571-9.
  • Rosenkilde M, Reichkendler MH, Auerbach P, Toräng S, Gram AS, Ploug T, Holst JJ, Sjödin A, Stallknecht BM. Appetite regulation in overweight, sedentary men after different amounts of endurance exercise - a randomized controlled trial. J Appl Physiol (1985). 2013 Sep 19. [Epub ahead of print]
  • Sim AY, Wallman KE, Fairchild TJ, Guelfi KJ. High-intensity intermittent exercise attenuates ad-libitum energy intake. Int J Obes (Lond). 2013 Jun 4. doi: 10.1038/ijo.2013.102. [Epub ahead of print]