Fat Loss and High Intensity Exercise

In my last post Fat Loss and the Case For Less Exercise, I explained how I’ve designed my exercise plan to be as minimal as possible to maximize my chances at fat loss without increasing my appetite or risk of injury.

My HIT workout takes about 15 minutes, which includes light mobility work. The sprint session takes about 10 minutes, where most of the time is spent walking back to the bottom of the hill. The rowing takes less than 5 minutes. Adding everything together I am exercising less than one hour per week.

To be clear, I am not saying this is the optimal plan for everyone. This is what has worked best for me. When I increase my exercise volume, I also increase my appetite and risk of injury. I covered this in detail in the post How Exercise Indirectly Kept Me Fatter.

On the surface, it appears the primary mechanism for fat loss is not burning calories, but increasing muscle gain. Increasing muscle increases metabolism which can result in greater fat loss. Up until I read Body By Science this was the only fat loss pathway I was aware of when it came to resistance training.

Body by Science
Body by Science by Doug McGuff and John Little is by far the best book I’ve read on fitness.

Forget The Fat Burning Zone, Embrace High Intensity

The Cult of the Cardio loves to preach that exercising in a range between 60% and 70% of maximum heart rate maximizes fat loss. They call this range the Fat Burning Zone. When we lower our intensity into this range, not only can we exercise longer, but we access fat at a higher percentage. Is this a good thing? Body By Science makes the case that it isn’t. Fat loss is not just about calories, it is also about hormones. Watch the two videos below (13 minutes in total) for a primer on High-Intensity exercise and fat loss.

BODY BY SCIENCE 5 (The Science Of Fat Loss — Part 1)

BODY BY SCIENCE 5 (The Science Of Fat Loss — Part 2)

I’m going to list some of the fat loss ideas from Dr. McGuff’s book. I had to read this section three times before I felt I felt I understood it. If my understanding is flawed, please help me out in the comments below.

  • The greatest metabolic effect comes when all muscle fibers are recruited.
  • When we aren’t accessing body fat directly, we get our energy from glycogen stores. Glycogen provides “on-site” energy to the muscular system.
  • Fast-twitch muscle fibers have the most glycogen stores.
  • Cardio does not tap the fast-twitch muscle fibers. High intensity does.
  • Because cardio does not meaningfully empty glycogen stores, circulating glucose in the blood must be stored as fat. The muscle cell walls lose their sensitivity to insulin. High-intensity exercise causes the opposite to happen.
  • Glycogen storage can diminish over time when we do not engage in exercise at a high enough level. When those glycogen stores stay full, excess glucose goes to fat storage. This can lead to both muscle atrophy and insulin resistance.
  • High-Intensity Exercise activates hormone-sensitive lipase. Low Intensity doesn’t. Lipase permits the mobilization of body fat.
  • Cardio produces more oxidative free radicals and inflammation than High Intensity.

Body By Science goes into much greater detail. I highly recommend buying that book. You’ll never step on a treadmill ever again and you’ll be leaner for making that decision.

When I embraced High Intensity in late 2010, my volume of exercise dropped. Because my intensity increased, the result was precisely what Dr. McGuff said in the videos above, I got leaner. In my next post, I will conclude my thoughts on exercise and fat loss with an idea of where we should be directing our resources to maximize fat loss potential.


Add yours

  1. Stuart Gilbert

    Apr 13, 2012 — 6:41 am

    I’m interested in the direction these recent posts on exercise are going. I am similar in how I exercise but I don’t use HIT or HIIT protocols quite as often during the week. Reading a previous post it seems as though with the sprinting, rowing and weights, HIT exercise is done up to 5 times a week. Isn’t there a case for too much of that exercise also, perhaps leading to burnout? Has the walking gone now? I do brisk walks / slow jogs between HIT sessions similar to the advice given from writers such as mark Sissons and Clarence Bass. I still feel that moving slow and often does have benefits. However as mentioned above, the 80%+ of max heart rate cardio on the treadmill, bike and running outside for 20 minutes plus has been ditched.
    I appreciate reading the informed thoughts on here concerning exercise.

  2. Thanks for these videos. I have the book at home, but haven’t taken the time to read it all the way through. I really like the idea of HIT (and HIIT), but I find for myself that if I’m not doing something on a daily basis I tend to forget about it completely. Then a week or two later I remember I was supposed to lift some weights at some point!

    I am going to give this program the chance I know it deserves. I think it would work for me as well, it’s just a matter of me figuring out a schedule/routine so I won’t forget about it and end up skipping workouts.

  3. @Stuart – For me the weight training portion (SuperSlow HIT and static holds) is a must. Adding in the sprints and rowing is a bonus. Some weeks I can do all three, but my bias is always toward safety. This week my leg press workout was so intense that I haven’t done any sprints.

    Slow jogs destroy me. I suspect it has to do with being 6’2.5 tall. Mr. Bass is 5’6. I touched on height and distance running in this post.


    I still walk, but I don’t consider it exercise. It is just part of being human. It is an interruption signal to the lack of movement that afflicts many in modern society.

  4. @Ali – The first time you do a HIT workout, make sure you don’t have anything important to do for the rest of the day and the following day. Read a book or catch up on movies. After my fist HIT workout, I went home and fell asleep, which is extremely hard for me to do mid-day.

  5. Stuart Gilbert

    Apr 13, 2012 — 10:10 am

    Thanks for answering the questions I asked. Much appreciated. I’ll check that link also. When I stated that I jogged it’s not a formal thing…I’ll start with a walk and if I feel energetic ( and it’s not uphill ) I might break into a slow ( and I mean slow…lol ) jog. I also consider walking and slow jogging to be part of movement and not formal exercise. If the weather is bad I will do this slow movement on a bike, recumbent, treadmill or elliptical ( not a fan of the rowing machine – at 5’7 I’m not good on it, with this machine taller is better ) i make sure to keep the heart rate under 130 ( which I believe for me at 45 falls into the Primal Blueprint guidelines ). The slow movement often helps me to recover from more intense sessions. If I’m too tired then I’m not scared to rest.

  6. Stuart Gilbert

    Apr 13, 2012 — 1:10 pm

    Also I train just 1 or 2 sets per exercise when I do weights. I used to do all the things like static holds , forced reps etc. However recent research and personal experience has led me to drop all that stuff. I do as much as I can do in good form. If I feel that there is not another rep in me then I won’t go for it. I feel this is healthier for the joints and promotes better recuperation. Also in Richard Winetts publication “master Trainer” a few months ago he wrote about a piece of research where the same response was noted from sets to failure and performing a few reps short of failure. I’d rather just stop short of the extreme of a static hold and train twice a week, more chances to make progress. And the jogging aspect of the slow movement is just something I do…I don’t think Clarence Bass jogs….he just walks….he has more sense and experience than me….lol.

  7. @Stuart – I mix it up between SuperSlow, static holds and then once every few months I will do a light volume workout without going to failure. I do that for mental reasons.

    The first time I started HIT, it didn’t stick. The second time it clicked. When I started seeing results without pain, I became a convert.

  8. This resonates with me, as I’ve read Pavel Tsatsouline’s books (higly recommend them) and they say much the same thing. You can also find some videos of him on youtube, some of which are demonstrations. He’s a fun and informative read. Thanks for the blog!

  9. I apologize for the length of this comment, and hope it doesn’t come across as critical of this blog. Now that I’ve read Body By Science I have a lot of problems with it, though I liked some of the information, too.

    As far as I can tell, your interpretation of the book (chapters 2 and 9) is fairly accurate, but I think the authors themselves are wrong in some places (or have oversimplified).

    Apparently it’s not necessary to train at a high intensity or eat paleo to become more insulin sensitive. Daily exercise will stabilize blood sugar (e.g. the Amish, who eat an agricultural diet including dessert but are very healthy because they do physical work every day – see Jeff O’Connell (2011) Sugar Nation). One day off and blood sugar starts to wobble again. I don’t know how intense the exercise needs to be but it’s probably moderate. If it protects from metabolic disorder it should also protect from obesity. Also, you don’t need HIT or to train to failure to gain muscle. That debate has been going on for decades. Maybe it depends on the person.

    The Body By Science workout is more or less the same workout as Pete Sisco’s Power Factor Training, which I did 8 or 10 years ago: training to failure then enough recovery to lift even more next time. For many people that means training once or twice a week to start with. For me that meant recovery times of 4 weeks, then 6, then 8, then 10, then 12, then it was time for hibernation season again. (My energy plummets in the fall.) Then there was the back workout where I had no real strength, because I’d taken three weeks’ worth of library books home a day or two earlier, preempting my training to failure with a killer real life workout. I tend to do things like that whenever I have the energy. Sisco mentions that there are people who can only train to failure once every six months if they want to make gains. For me even that is impractical, mostly because of my tendency to use up my energy on adventures (like those books, or the 30lb chair I decided to carry home from the store, or the 50lb box of frozen meat I lugged home on the bus), plus my drop in energy in winter.

    At the beginning the authors cite a study where brief high intensity training was as effective as regular running, which they took to mean high intensity is better, because of the injuries associated with regular running (p.17). I think someone who loves running would look closer at running before dismissing it. The barefoot running movement was just taking off at that time, but research on the harm done by shoes had been published already, including Marti (1989) and Robbins (1987-1998) (papers by Marti and Robbins available on Robbins’ website: http://www.stevenrobbinsmd.com) and others before and since. Lieberman’s theory that the genus Homo evolved to be endurance runners/persistence hunters was still new/in the process of being published, so they get a pass for not addressing that, but they’d need to, now, I think. Is it running that’s bad, or the way people were going about it? Or does it depend on the person?

    There is a major fail on Sheldon’s somatotypes: there are three *axes* of measurement, not three types; there are about 90 types in the “Atlas of Men” and more recently researchers have combined these into 7 major groupings: balanced endomorphy (2.98% of men, about 11% of women**), balanced mesomorphy (11.8% of men, about 1% of women), balanced ectomorphy (7.03% of men, about 12% of women), endomorphy-mesomorphy (14.82% of men, about 20% of women), ectomorphy-mesomorphy (10.6% of men, about 1% of women), endomorphy-ectomorphy (1.44% of men, about 10% of women), and central (51.3% of men, about 45% of women). You need to describe a minimum of those 7 body types to be able to say anything meaningful. Most of what’s on the internet about body type is fairly inaccurate. I recommend reading Sheldon in the original.

    [**percentages for Sheldon’s sample – USians of European descent, therefore sample biased in favour of low ectomorphy because of adaptations to cold; people from hot climates will have higher ectomorphy and East Asians will have more endomorphy. Body type differences by region/climate may make the findings in Body By Science less applicable to populations not descended from Europeans and to people lower in endomorphy or higher in ectomorphy. About 2/3 of white people appear to be either central or endo-meso types, which makes those who aren’t outnumbered in research. Unless you control for body type you don’t know how universal the findings are.]

    The authors appear to be seeking the one true answer, but there isn’t going to be one because biology is always more complex than that. Some people have more natural endurance, and I think that’s due to endomorphy. Some people have more explosive energy than others, and I think that’s mesomorphy. It’s possible that some body types have more slow twitch fibres, and need to concentrate on fast twitch to find balance, while others have more fast twitch and may need to focus on endurance. There are mesomorphs who do nothing but aerobic training, and they seem to be fine. They certainly don’t need to build more muscle or train to failure for health, and training to failure may actually be bad for them, or at least a hassle (as it is for me). Plus it’s possible that they have to make much less effort to train intensely. (No idea because I haven’t seen any research.) I know that I need to concentrate to slow down because I’m very explosive/intense, and can overtrain just walking down the sidewalk. Keeping my heart rate in the bottom half of my range (as per John Douillard’s “Body, Mind and Sport”) has been the most helpful and longest-lasting form of training I’ve ever done. But someone higher in endomorphy might not need to worry about that at all. See also “Dr Abravanel’s Body Type Diet” for examples of how food cravings, body fat distribution, and optimal diet, meal scheduling and exercise can vary with body type.

    Except for body types, I don’t question the research they report – I don’t know enough about it to – but I do question their narrow interpretation. Other interpretations are also possible, plus there’s a need to take different body types/body chemistries into account.

    I’m really glad you recommended the book, and that I’ve read it, but it’s made me realize I need to throw out every theory and exercise plan out there and just listen to my body, since I’m not average and they don’t seem to be studying people like me.

  10. Power Factor Training by Peter Sisco and John Little.


    It’s probably more or less the same workout as Body By Science because it’s the same second author. There was a comment in one of the articles on the BBS website about someone taking 6 weeks off from an injury and expecting to be weaker but actually being stronger, and I thought, gee, I’ve read this before, does it happen often? but didn’t think to check the second author of PFT until last night.

    When I did PFT I was doing one set to failure and spacing each muscle group out to one a week to start with (and further apart later on) so they’re comparable for me. (PFT recommended 2-3 full workouts a week to start and multiple sets, but I wanted that 6-week-off edge.) And I did make gains as long as I kept increasing recovery time. It just got to be too impractical.

    Another group it might not help is people who are only a 1 in mesomorphy (out of 7, including extreme ectomorphs and extreme endomorphs) – they aren’t likely to gain no matter what they do. They’re rare but they do exist.

    I can see it helping most people a lot, though.

  11. I’ve read 3 other books by John Little, but not that one.

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