I believe regular movement and exercise is essential to health. As Stephan Guyenet pointed out in a recent blog post, our paleolithic ancestors had a different word for exercise: “life“. They naturally spent a lot of time outdoors in the sun, walking, hunting, gathering, and performing various other physically-oriented tasks. They had no concept of this as “exercise” or “working out”. It was just life.
But while exercise contributes to health in several different ways, it’s not very effective for weight loss. Or, more specifically, I should say that low-intensity, “cardio” – which is how most people exercise – is not effective for weight loss.
Why Cardio Doesn’t Work
How could this be? There are three main reasons:
- caloric burn during exercise is generally small;
- people who exercise more also tend to eat more (which negates the weight regulating effect of exercise); and,
- increasing specific periods of exercise may cause people to become more sedentary otherwise.
In an example of the first reason, a study following women over a one-year period found that in order to lose one kilogram (2.2 pounds) of fat, they had to exercise for an average of 77 hours. That’s a lot of time on the treadmill just to lose 2 pounds!
In an example of the second reason, a study found that people who exercise tend to eat more afterwards, and that they tend to crave high-calorie foods. The title of this study says it all: “Acute compensatory eating following exercise is associated with implicit hedonic wanting for food.” I love it when researchers have a sense of humor.
In an example of the third reason, one study assigned 34 overweight and obese women to an exercise program for 8 weeks. Fat loss at the end of the study was an average of 0.0kg. Not very impressive. But the researchers noticed that some women did lose weight, while others actually gained. What was the difference?
If you’re still not convinced, the Cochrane group did a review of 43 individual studies on exercise for weight loss. Study length ranged from 3 to 12 months, and exercise sessions lasted on average 45 minutes with a frequency of 3-5 times per week. The results? On average, the additional weight loss from exercise averaged about 1 kg (2.2 pounds). Meh. Assuming they worked out for 45 minutes 4x/wk over 6 months, that means they had to exercise 69 hours to lose that 1 kg.
The purpose of this rather long introduction is simply to point out that low-intensity, “cardio” exercise is spectacularly ineffective for weight loss. But that doesn’t meal all types of exercise aren’t effective.
High-Intensity Intermittent Training (HIIT)
HIIT is a type of exercise performed in short bursts (intervals) at high-intensity. Several studies have been done comparing HIIT to low-intensity, steady-state (“chronic cardio”, as Mark Sisson calls it) exercise, and HIIT has been shown to be superior in nearly every meaningful marker.
In this study, one group was assigned to “chronic cardio”, while the other was assigned to intervals of 8-second sprints. After 15 weeks, the researchers concluded:
Both exercise groups demonstrated a significant improvement (P less than 0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels.
A pair of studies done at McMaster University found that “6-minutes of pure, hard exercise once a week could be just as effective as an hour of daily moderate activity“, according to the June 6, 2005 CNN article reporting on the study.
The study itself was published in the Journal of Applied Physiology, and it revealed that HIIT resulted in unique changes in skeletal muscle and endurance capacity that were previously believed to require hours of exercise each week.
A follow-up study confirmed the results. Despite the fact that the more conventional endurance exercise group spent 97.5 percent more time engaged in exercise, both groups of subjects improved to the same degree. The group that exercised 97.5 percent more received no additional benefit whatsoever from doing so. Considering the wear-and-tear and increased risk of injury associated with that much more exercise, there’s absolutely no point to doing “chronic cardio” when you can receive the same benefits with a fraction of the time and risk by doing HIIT.
The Cochrane study I linked to earlier in the article also found that high-intensity exercise was superior to “chronic cardio”. In particular, the researchers found that high-intensity exercise led to a greater decrease in fasting blood glucose levels than low-intensity exercise.
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Why High-Intensity Exercise Is Better
In his excellent book on high-intensity strength training, Body By Science, Dr. Doug McGuff explains that high-intensity training is superior to chronic cardio because it produces a greater stimulus and thus more effectively empties the muscles and liver of glucose. This stimulus can last several days with HIIT, as opposed to just a few hours with low-intensity training.
High-Intensity Strength Training: Best of All?
Both high-intensity running or bicycling sprints and high-intensity strength training are effective. But I believe high-intensity strength training is probably a better choice for most, simply because the wear-and-tear and risk of injury is lower – especially if the strength-training is performed using weight machines as described in Body By Science.
This is, in fact, the method of training I’ve been doing since April of this year. I admit I was somewhat skeptical about it all before I read Body By Science. But the research and the physiology was convincing, so I decided to give it a try.
The results have been incredible. My workout varies in length between 5 and 9 minutes a week. That’s right, I said minutes. With only a few exceptions, I’ve increased the amount of weight I can lift, the time I can lift it, or both, with each successive workout. My strength has increased and my physique is, if anything, better than it was when I was lifting 3x/week for much longer periods.
Aside from the Body By Science (BBS) weight workout which I perform once a week, I stay active on a daily basis. I ride my bike or walk to work or to do errands, and rarely drive my car. I go on walks in the woods or on the beach. I surf when time permits. But I don’t do anything else for “exercise”. This routine not only feels great, it fits very well with my lifestyle and it is completely sustainable. It doesn’t feel like an effort at all.
If you’re interested in this kind of training, I’d recommend picking up a copy of Body By Science and checking out their excellent blog. You can post your weekly workout results and get help and suggestions from the very knowledgeable community there – including both authors of the book, Doug McGuff & John Little, and other experienced trainers and enthusiasts.
Another option that may be more accessible for some is Fred Hahn’s The Slow Burn Fitness Revolution. Fred also has a website and blog worth checking out.
Final note to slackers: the popular excuse of “I don’t have time to exercise” is no longer valid. You’ve got 6 minutes a week to do this. I know you do.
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I have known for some time that exercise decreases fasting blood sugar levels and always recommend diet and exercise to my clients. The HIT form of exercise seems to have some benefits but I was wondering whether you found any research showing that it results in immediate spikes in blood glucose in people with decreased insulin? My type 2 diabetes clients sometimes experience higher blood glucose readings after more intense workouts. Fortunately, it then decreases but I have typically recommended moderate-intensity workouts.
Tips to Lose Weight Fast
Fats are enemies of the diet. They provide too many calories. It is therefore recommended steamed, grilled and use the microwave. The natural food is also healthier and better maintains the vitamins and minerals from food.
Food is a pleasure. You have to enjoy eating. The diet should not be torture. Thus positive change menus. A diet that causes suffering is not a good diet.
Do not obsess over the scale. Once weekly should be weighed naked and fasting. Losing weight is a progressive achievement.
No snacking. Do between meals is all you get for storing fat and pulls all the efforts to meet the diet. If you can not avoid it, it is best to eat pieces of fruit, nonfat yogurt … calming hunger without consuming calories.
Find out more here: http://howtolosebellyfast.blogspot.com/
Stopped reading at “fats are enemies of the diet”.
It’s true. My running years have left me with awful back trouble and I only ever lost weight that stayed off by sorting out my diet and selling the cross trainer! Gyms and personal trainers are making big bucks along with diet industry!
Indeed it’s about energetic metabolism, when you do what is known as “aerobic” is actually involving a great part of the anaerobic lactacid metabolism, which use glucose as energetic substrate. Since adaptation to exercise is about overcompensating what you lost, the more you use glucose, the more you crave it after. Moreover, this provokes suffering, if you look in nature animals don’t do jogging, they have brief sprints, and children as well play like that by instinct, they avoid suffering because in nature it means hazardous. When you perform an HIT routine, you use very few glucose, mostly ATP-CP and after about 10 seconds you start to rely on glucose. When you have to compensate CP and few glicogen, you are much less likely to crave sugar.
Moreover with a long routine you’re going to stimulate cortisol, that wreak the already discussed havoc.
A recent italian study by Ugo Carraro demonstrated the activation of the muscolar stem cells during a brief High intensity routine. When the ATP-CP reserves are depleted at the moment, muscolar fibers break stimulating the activation of the stem cells. During the recover new fibers are generated from such stem cells, and it could take even 14 days to complete the process. During that time they use the fat nearby because it’s an aerobic process, leading to the spot reduction, a process well known among bodybuilders but still denied by some “official” doctors.
Hey Chris,
nice article, love the blog.
I have some criticism regarding Body by Science though. I read the book last summer and became convinced of the methodology – I tried it for several weeks and it just didn’t work for me. Now, of course that’s merely personal anecdotal evidence – so I started to look for more information about HIT training, and I came across Malcom McDonald’s website (bodyrecomposition.com). I started a thread about HIT and BBS in particular, and got overwhelmingly negative responses not only by Malcolm himself, but also linking to others.
Long story short: I think that the protocol they advocate in BBS is far from the one-all-end-all solution to strength training. In essence, going to failure is way too much stress for the CNS, thus preventing you from training more often. In december I tried a more traditional approach (3 sets of 6-8 repetitions two times a week, not going to failure), and not only did I quickly start gaining strength and muscle mass, but I also felt much less exhausted between sessions.
Note that I still agree with the premise that you should aim for short, intense training sessions (e.g. at most 40 minutes). 6 minutes per week is surely enough to help restore some insulin sensitivity in obese couch potatoes, but if the goal is functional fitness and strength, I think that 2×30 minutes per week is a much more realistic target. It’s still something that anyone should be able to include in ther schedule though, especially when you do body weight exercises at home. Squats, pushups, pullups/reverse-rows, planks – you really don’t need much more than that.
@Jessica
I assume you are a troll – but in case you are sincere, here are analyses of some studies showing serious heart abnormalities in marathon runners.
They were written by a medical doctor (me) who agrees with both Chris Kresser and Dr. Doug McGuff on the health superiority of resistance training over high volume high intensity ” cardio”
http://www.paleonu.com/panu-weblog/2009/11/1/cardio-causes-heart-disease.html
http://www.paleonu.com/panu-weblog/2010/3/21/still-not-born-to-run.html
This would not work for me, and I suspect a lot of other people too. I need to do a long slow warm up of all my muscles and joints before doing anything high-intensity. Otherwise I end up injuring a muscle or joint and thus defeating the whole purpose. So this would still end up being a good 30 minute workout. And I refuse to believe you can get away with only doing it once a week. All the advocates of this – like yourself Chris – have active lifestyles. I sit at a computer all day. I walk perhaps an average of 30 minutes a day but that’s it. 6 minutes a week cannot possibly be enough.
Thanks for the great post… I will check out that book also. I was a reluctant converter to high intensity and am so glad I did! I trained for a triathlon last summer and while I was improving, I wasn’t seeing the results I was hoping for. I initially added high intensity (tabata sprints, kettlebells) to my regular 2 hour a day training regimen, but when I started seeing good results, I tapered down my cardio training. The last two weeks before the race were high intensity sprints and high intensity strength with no cardio. Final result: I shaved several minutes off my time in each area from the last time I timed myself after training just cardio. I also finished in much less time than I expected (an hour 30 minutes for a sprint triathlon) and had almost no soreness the next day. I also ran it on an entirely paleo diet with no carbs before, during or after.
Not saying my experience by any means proves anything scientifically, but it made me a believer!
@ Jessica- I am trained in nutrition, rather highly trained actually, so that is my area of expertise as medicine is to a doctor. I know many doctors who admit that nutrition and exercise are not their specialties, which is why many refer to nutritionists and personal trainers in recommending things to patients. I’ve also talked to a lot of doctors on many of the points that Chris also brings up on this site, and many truly do not understand the physiological effects that certain types of food have on the body. Take for instance the much-debated “healthy whole grains.” While most doctors recommend them based on the food pyramid or other outdated marketing efforts, I am yet to meet a single doctor (or anyone else) who can explain away the negative effects of gluten, lectin and phytic acid.
@Jessica –
Doctors are great when you break your leg… or get in a serious car accident and need emergency surgery to close a bleeding blood vessel… or if you get pneumonia and need antibiotics… or countless other similar examples.
However when it comes to diet, nutrition, exercise, and what it takes to live a healthy lifestyle that minimizes the risks of developing chronic diseases, I think most honest doctors would admit they don’t have a clue. I’m only 37 years old, yet it’s amazing how many times they keep changing and adjusting the recommendations for what’s supposed to be healthy and what’s supposed to be bad.
Also, keep in mind that most doctors get their information from medical studies (mostly funded by drug companies — gee, think there’s a bias there to make money pushing pills?). Yet statistical analysis of the most cited studies from the past decade show almost all of them are biased, and as such, we can’t rely on their results. Atlantic magazine has a great article on that: http://www.theatlantic.com/magazine/archive/2010/11/lies-damned-lies-and-medical-science/8269/
On this site, Chris routinely cites scientific papers in his posts. Perhaps the studies he references are also biased in the manner discussed in the Atlantic magazine article. Perhaps all studies are flawed. So what are we then left with? I’d say common sense and history. If massage therapists see tons of issues with long term runners, that should tell all of us something. If people see real health improvements doing the type of exercises mentioned in this post, that also should tell us something. Finally, like Chris did at the beginning of the article, if we look back to history and realize healthy humans existed before the year 2000, yet had no concept of the term “exercise” then we should probably be able to admit that running miles each week, or doing a stair-stepper for 5 hours each week, aren’t mandatory for good health.
Thank you, Chris. I’ll take a look at one of those books.
I can tell I’m losing muscle as I age, and my upper body strength is nothing like it used to be.
I’m one of those people you talk about in your post who “just doesn’t have time” (or motivation).
We do have a nice set of free weights in the basement collecting dust. We’ve made a LOT of diet changes, for the better, in the last year. Strength training is reluctantly on the ToDo list.
The Power of 10 or Fred Hahn’s book I mentioned in the article are both good choices for beginners. Body By Science is my favorite, but it can be a bit intimidating for those starting out.
Any book or web site recommendations for out of shape beginners, in their late 40s?
A doctor tested my blood pressure 140/90, asked for family history and concluded I had it in my genes and should take pills for life (good for the Pharma). I read the internet, changed my diet and life style and get by without pills and BP 115/75. It is in the Medicine establishment’s interest to have more clients for longer – it is logical and I do not blame them, they have families to feed.
@Jessica – What makes you think Dr. Oz is not making money from going on shows? Doesn’t that mean he is no longer credible?
I would also like to know if you have ever take the time to actually read the “scientific evidence” that Dr. Oz presents? Half the time he doesn’t even site what he claims. The fact that these all knowing Doctors actually test for total cholesterol AND tryglycerides is an oxymoron. A bit of advice if you don’t want to end up like the rest of the western world read a little.
@Jessica Santos: You’re delusional. Sorry. But I’ve had enough bad experiences with the medical profession over the years to know that they’re nowhere near as omniscient as you seem to think.
My doctor is actually quite interested in this “paleo diet nonsense” after he saw it eliminate my and my wife’s prediabetes, lowered our blood cholesterol, and eliminated a condition I had had for 16 years, and which he had prescribed surgery for.
If you had any idea what you were talking about, you’d be aware there are lots of scientists and doctors who are “promoting” this nonsense, because it works.
@Chris Kresser: You wrote: “Several studies have been done comparing HIIT to low-intensity, steady-state (“chronic cardio”, as Mark Sisson calls it) exercise, and HIIT has been shown to be superior in nearly every meaningful marker.”
Mark Sisson and Art De Vany both make the case that “chronic cardio” is, in fact, bad for you. The term comes with some baggage, that apparently you weren’t aware of. There do seem to be “meaningful markers” where cardio, running in particular, seems to offer benefits not available through other forms of exercise.
I don’t know anything about the cortisol issue you raise, so I’ll just assume you’re correct.
Other than the baggage that comes along with the “chronic cardio” term, I think it’s a great post. 🙂
I don’t believe I argued in this article that “chronic cardio” is bad for you, or that I have ever made that argument elsewhere. (With one exception: I think there’s evidence that frequent cardio raises cortisol levels and if someone has cortisol dysregulation, chronic cardio could make it worse.)
The argument I made in this article is that HIIT produces equivalent (or in some cases superior) physiological adaptations to “chronic cardio”, in a fraction of the time and at a fraction of the risk.
Some people enjoy running, doing the Stairmaster, etc. But many do it because they think they have to in order to get the cardiovascular benefit. Those people might be glad to learn they’re mistaken in that belief, and that they can in fact receive the same benefit in just 6-8 minutes/week.
Chris,
I noticed that this article was written several years ago. Are you still following this exercise regime?
Thanks for the great info you provide.
@James Steele: What first paper I cited showed was that “endurance athletes” had a later onset of osteoarthritis than athletes such as weight lifters. This contradicts the “chronic cardio” premise.
@James Steele: But if something’s really bad for you, you’d expect to see some evidence of it.
The Stanford study I mentioned specifically compared healthy runners to healthy non-runners, expecting to find that runners did worse over time. They found the reverse. Runners did dramatically better than their fit, non-obese, non-smoking non-running counterparts over a 21 year study.
Lower *all-cause mortality* is more than “a few conditions”. You wouldn’t expect that running protects against cancer, for instance, but it’s linked with a lower incidence of cancer in that study.
I’m open to the idea that running might be bad for you. It might be. But all the evidence seems to indicate the contrary. If you have any evidence to support your position I’d love to see it. I know that none of the folks who make the “chronic cardio” argument have anything other than anecdotal evidence, as this thread so far demonstrates.
@Tuck
“There are a number of epidemiological links between running and lower instances of disease”
I just wanted to point out the epidemiological part of this. A group of people who run just happen to have lower risk for a few conditions. Hmmm great. The Kitavans have great health and also smoke, maybe I should take up smoking. Sorry for the sarcasm, the point was that, as most people here are aware, an epidemiological link does not imply causation. The arguments against running certainly have more biological plausibility which might lend a little weighting to other papers showing epidemiological links between running and poor health outcomes.
Also from the paper cited –
“We grouped the athletes according to the type of sports training. Endurance sports are those that require a high amount of repetitive loading of the weight bearing joints, mixed sports include those with a greater risk of high impact loads and sprains of the joints, and power sports include sports producing less repetitions but higher forces when loading the joints (table I).”
The paper doesnt really show that running is better than resistance training. The sports included in this study involved high impact loading, including running which imposes ground reaction forces up to around 6 times bodyweight on joints, and I’m willing to bet that the ‘weight lifters’ were not performing BBS style slow controlled lifting. All this study shows really is that consecutive impacts can put you at higher risk of osteoarthritis and the higher impact sports result in this condition earlier than lower impact. The implication is not running is better, the implication is really that impact sports in general aren’t good for your joints. Every group had a higher incidence than controls.
James
Jessica: many readers of this site are, in fact, doctors. From all over the world. If you have a constructive critique of the research or analysis, please present it. Otherwise your accusations have no merit.
I invite anyone, doctor or otherwise, to try to debunk the information here. That’s the spirit of scientific inquiry, and it’s the nature of this site.
My readers are critical thinkers who do not simply accept something because a doctor says it. That’s such a preposterous notion that it isn’t even worth challenging. You’re unlikely to convince anyone here with that kind of flawed logic.