You reckon she got that lean simply by doing HIIT three times a week? Read on and decide for yourself... High-intensity interval training, more commonly known as HIIT, has skyrocketed in popularity during the last decade. Sprint On, Sprint Off… Most of you by now have heard about the HIIT protocol of Japanese researcher Izumi Tabata, which entered the Western consciousness in a big way after the now-defunct Muscle Media magazine wrote a glowing article about it back in 2001 you can read the original article. After the last sprint, you cool down with another four minutes of 50% effort, before jumping off the stationary bike, puffing your chest, and crushing a can of Solo against your head. What it did do was compare the aerobic and anaerobic conditioning effects of the Tabata HIIT protocol with steady state cardio, then later with another HIIT routine involving longer active rest periods. If this all sounds reminiscent of the MAD charlatanism brought to us by the not-so-friendly folks at Low Carb Inc. However, unlike the MAD bollocks, there is actually a kernel of truth in the HIIT EPOC story. But only a kernel. From this wee kernel sprouts the observation that if you compare a high intensity and low intensity activity — matched for work output — the former will usually produce a greater EPOC than the latter. But in real life, this scenario is not always applicable. Tell me — if you do eight twenty-second sprints on an ergo, or jump on a real bike and ride in the hills for 90 minutes at a fast clip, and include a few Marco Pantani-inspired moments where you attack a steep section with extra pep, do you honestly believe the brief HIIT session will cause the greatest EPOC? The reality is that EPOC is not just affected by exercise intensity - EPOC increases linearly with the exercise duration. As I have stated countless times on this site and in my book , fat-derived weight loss is all about calories. Calories, calories, calories, calories, calories, calories, calories, calories, calories, calories, CALORIES! Damn I love that word. Look, there goes another low-carber! It bemuses me to no end to see people trying to devise all manner of clever routines that will somehow send their metabolism off into the stratosphere and burn fat like butter in a fry pan, and yet ignore the most fundamental equation that underlies every successful fat-derived weight loss attempt: CALORIES IN MUST BE LESS THAN CALORIES OUT. Do me a big favour and unlock the fat stores, will ya? If you conduct a clinical trial and tell the obese participants to walk 3 times a week, or you give them a more vigorous program but simply tell them to keep eating as normal, what do you think is going to happen? What are you on? Meaning that if you acknowledge the calories in versus calories out equation, the addition of exercise to your fat loss regimen will speed things up nicely. The bottom line is that if you are trying to design an effective fat loss program that will take you from overweight to jaw-droppingly lean, you sure as hell better acknowledge the primal role of calories. Either that, or go buy yourself a girdle. Alright Anthony, But What About HIIT? Either that, or things are real quiet at work. So without further ado, here is a quick ish look at the surprisingly sparse research examining the effect of HIIT on fat loss. In a fifteen-week study by Tremblay et al comparing Canadian men and women who performed either HIIT or lower-intensity stationary cycling, little overall weight change was noted in either group. As is unfortunately par for the course in these types of studies, dietary intake was not controlled. But clearly the subjects in both groups ate sufficient calories to maintain weight on their assigned routines. Unfortunately, this study had some discrepancies that preclude us from placing too much faith in the results. To determine body fat changes the researchers used only skinfold measurements, which are not as accurate and consistent as underwater weighing, DEXA dual-emission X-ray absorptiometry and MRI. Either this group were biological freaks who could lose fat in one area but gain it in another, or there were inaccuracies in the skinfold measurements. The HIIT and steady-state groups each trained for 15-weeks. Meanwhile, the control group continued to sit on their dimpled butts eating low-fat muesli bars watching Home and Away, Neighbours, and all that other incredibly banal brain-numbing pap that constitutes prime-time soap opera TV in this here sunburnt country. The average energy expenditures during the HIIT and steady-state sessions were 199 and 193 calories, respectively. As with the previously discussed study, there was no dietary intervention; all subjects, including the exercise groups, were instructed to continue their normal eating habits throughout the study. At the end of the study, cardiovascular fitness had improved significantly in both groups, but only the HIIT subjects experienced fat loss. The HIIT group experienced a mean 1. The steady-state group lost 0. Other findings of note were that the fat loss effect of HIIT was greatest in the obese participants and far less pronounced in the women who were already lean. The HIIT group also enjoyed far greater reductions in resting insulin levels, indicating superior improvements in glycemic control. This may simply have been an artefact of the greater weight loss in the HIIT group weight loss itself often produces notable improvements in glycemic control. So in this study, HIIT did indeed produce a greater fat loss than steady-state training. But given the similar energy expenditure between the two training regimens, a greater calorie burn during training did not explain the difference. In this study, it would appear the HIIT regimen may have blunted appetite more effectively than the steady-state routine. Or maybe the HIIT subjects really did experience some serious EPOC - but we'll never know because it wasn't measured. For those of you wanting to replicate the results of this study, it should be pointed out that the HIIT routine consisted of eight-second sprints followed by 12 seconds of slow pedalling. No problem, you say? Yeah, but this wasn't your usual 6-8 sprints - the HIIT subjects performed sixty of these sprints each session! Hey, where did everyone go? That is fair dinkum un-Australian all-encompassing Aussie catch-phrase, especially popular with vote-seeking politicians and pious Prime Ministers, for any kind of behaviour that causes offense. And what did they find this time, I hear youse all asking? First I have to explain what these researcher blokes and their subjects actually did, and then reveal the results. So sit your fat bums back down, grab a coldie, put ya feet up, and let me bloody well finish. Unlike the previous study with women, there was no longer-duration-lower-intensity cardio group. The exercisers and controls were similar in age 24. Five subjects later withdrew from the exercise group and three from the control group. As for diet, subjects in both exercise and control groups were advised to maintain their normal eating habits during the study. You know, the usual free-living carry on; unfortunately, metabolic ward trials are quite expensive and funding these days tends to be diverted to far more important things like conducting yet more dodgey studies that are halted early to give the impression statin drugs work in healthy people. No more nookie with Snooki, you stoopid giamope. The only other rules are no Galliano, Sambuca or Jägermeister within 3 hours of training, and no wearing hahaha. The HIIT group once again performed 8-second sprints interspersed by 12-second bouts of slow pedaling. They did this continuously throughout each 20-minute session, which was performed 3 times weekly for 12 weeks. As subjects adapted to the HIIT training, workload was increased so that HR stayed at the appropriate 80—90% peak level. The average HR during the HIIT training sessions was 160 ± 9 beats per minute, which corresponded to 88% of peak HR. Now THIS is sprinting... Okay, so what happened by the time week 12 rolled around? Not surprisingly, HIIT resulted in a measurable increase in cardiovascular fitness with absolute VO2peak being increased by 13% and relative VO2peak by 15%. In other words, their lungs could now perform at a given workload with noticeably less huff and puff than 3 months earlier. Total body mass decreased in the exercise group by 1. The fat mass of controls was unchanged after 12 weeks. And while greater fatness often predicts greater fat loss in dietary intervention weight loss studies, and also predicted greater fat loss in the earlier trial with women, in this trial initial percent body fat in the men was not correlated to changes in percent body fat after the HIIT intervention and unlike the earlier female study, this trial saw no changes in measures of insulin or insulin resistance. As for fat-free mass which includes precious muscle , the HIIT group experienced a 1. The earlier study with females found trunk lean mass was increased by 0. To keep things in perspective, after three months BMI in the men went from 28. So the participants started the study overweight, and finished the study overweight. It was a similar scenario for the women in the earlier trial; their mean trunk BF% started at 36. With higher volume exercise and judicious calorie restriction, 0. But that would be with a damn sight more exercise than 60 minutes a week, and with a conscientious effort to consume a predetermined level of calories, one that would allow for a sufficient calorie deficit to occur. Oops, another low-carber just collapsed — someone call an XXXL ambulance! For those of you wanting to get that lean athletic look, under 10% for men and around 15% or under for women usually does the trick. So what the above studies show is that a few 20-minute HIIT workouts a week is simply not going to be sufficient to get you there if you are presently carrying a serious amount of flab. Without accompanying caloric restriction nor any additional longer-duration exercise, the 200-calorie per session calorie burn of a brief HIIT session is simply not enough to produce the kind of fat loss that will produce noticeable changes in your appearance, regardless of any accompanying EPOC. And while the shameless marketers of intermittent fasting, low-carb and super-slow training books will rush to accuse me of shameless marketing for mentioning this, I explain in a fool-proof but not sub-moron-proof... Feed Ramone the Dog with the Hugest Appetite in Australia Fund. And before I get the usual pack of galahs a few snags short of a barby chastising me for hating on HIIT…hold your horses, you living brain donors! The fact is I love HIIT. HIIT is also the cardio of choice for folks who are trying to gain muscular weight. Brief, explosive forms of cardio will not just permit muscular gain, they will quite likely enhance it see legs of speed skaters and top track cycling sprinters for convincing visual evidence of this phenomenon. The well-muscled pins of British track sprinting superstar Sir Chris Hoy. Anyways, I hope youse all enjoyed my take on the current state of HIIT fat loss research. If not, youse can all get stuffed! Under normal circumstances, AnthonyColpo. However, the author is himself Italian-Australian, so just harden up, you pack of bloody sooks. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Medicine, 2003; 33 14 : 1037—1060. Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism, Jul, 1994; 43 7 : 814-818. The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. International Journal of Obesity, 2008; 32: 684—691. Acute effects of exercise intensity on appetite in young men. Medicine and Science in Sports and Exercise, Jun, 1988; 20 3 : 222-227. Effects of exercise intensity on food intake and appetite in women. American Journal of Clinical Nutrition, Nov, 2004; 80 5 : 1230-1236. Comparable effects of moderate intensity exercise on changes in anorectic gut hormone levels and energy intake to high intensity exercise. Journal of Endocrinology, Dec, 2009; 203 3 : 357-364. The Effect of High-Intensity Intermittent Exercise on Body Composition of Overweight Young Males. Journal of Obesity, 2012. Absence of exercise-induced variations in adiponectin levels despite decreased abdominal adiposity and improved insulin sensitivity in type 2 diabetic men. European Journal of Endocrinology, 2003; 149 5 : 421—424. Copyright © Anthony Colpo. Disclaimer: All content on this web site is provided for information and education purposes only. Individuals wishing to make changes to their dietary, lifestyle, exercise or medication regimens should do so in conjunction with a competent, knowledgeable and empathetic medical professional. Anyone who chooses to apply the information on this web site does so of their own volition and their own risk. The owner and contributors to this site accept no responsibility or liability whatsoever for any harm, real or imagined, from the use or dissemination of information contained on this site.
