How Not to Train for an Endurance Event

It’s Friday, everyone! And that means another Primal Blueprint Real Life Story from a Mark’s Daily Apple reader. If you have your own success story and would like to share it with me and the Mark’s Daily Apple community please contact me here. I’ll continue to publish these each Friday as long as they keep coming in. Thank you for reading!

real_life_stories_stories-1-2What if I stopped procrastinating on writing my story? Why haven’t I written it so far? Is it worth it? Is it boring? Maybe yes or maybe no. If I don’t start, I think I will never know. As I fly from Houston to Europe, I’m getting it done. So what do I want you to take away after reading these pages? I want you to know my story first, then relate it to your own journey and why you are reading another story about weight loss. Is my story only about weight loss? I’ll let you decide.

First, I grew up in South America—a place where the culture encourages people to over eat corn, rice, and wheat flour (pretty much lots of refined carbohydrates). So when I was growing up, I was never skinny. I had a few extra pounds, but I was active enough to be strong. When I was 14, I fell in love with mountain biking and mountain trekking. The two activities became my sports and I would do them three to five times a week. But for my diet, I was still eating lots of food. So what was the problem? I was in my late teens, strong, never slim, but not fat. The catch was, the problems came later.

Fast forward five to 10 years, and I was in my mid to late 20’s where I began facing high cholesterol. But I thought, “Isn’t that genetic? I must not be able to change it.” Mind you that in those 10 years I had also managed to put on 30 to 45 pounds of weight. Diet after diet, I would loose 10 to 15 pounds, then regain all the weight and then some.

Another nine years went by without any major changes to my diet. All the while, I still thought biking was my perfect exercise, although I kept on the 35 to 45 pounds of excess weight. You see, I’m 5′ 11″ and when I was 18 years old I was 182 lbs. But by the time I was 39, I had reached 217 lbs. What just happened? How did I do that to myself? Well, it turns out it’s not so tough if you eat rice every day, pasta at night, cereal and bread in the morning, and couple that with hardcore biking. It was a complete recipe for disaster.

mauricio 1

It was the end of 2012. I had signed up to bike the MS150, which is a road bike event that goes from Houston to Austin in two days. I thought that if I set a hefty goal of biking 160+ miles in two days, I would be able to drop weight. So I was determined to start road biking more than mountain biking.

One thing I have not told you about me is that I’m an engineer. To say that engineers love data is an understatement. I charted blood test data in time, monitored my heart rate during all my trainings, recorded map and mileage data, etc. You get the picture. I had a lot of cool charts and numbers. But the only number that never seemed to go down was my body fat percentage.

As I was reading about training for the MS150, the more it became evident that I had to shift my focus from losing weight to decreasing my body fat percentage. Why? Because I had 32% body fat. I don’t want to go too heavily into the math of it, but here’s a little trick. Grab the number 32 and imagine a point to the right of it. If you do this, you’ll get 32.00. Now, grab that point and slide it to the left two spaces. The number then becomes 0.3200. If you take away those two zeros to the right, you get 0.32. Now grab my total weight at the time, which was 217 lbs, and multiply it by 0.32. That breaks down to 217 lbs x 0.32, which equals 69.44 lbs. What did I just do? I gave you the total amount of fat that I was carrying in my body. I once grabbed a plastic bag and filled it with water until the weight hit 69 lbs. Wow! That was a lot of fat I was carrying!

mauricio beforeSo with a new goal of decreasing my body fat percentage—because a healthy one should be around 12 to 16%—I needed to drop around 30 pounds. I was ready! So there I was, training for my endurance bike ride. After 10 or more rides, were I would ride anywhere from 30 to 75 miles, something strange started to happen. My great charts were showing my muscle mass was dropping and I was gaining fat! I thought, “How is this possible?” I was killing myself riding for seven hours at a super high rate and I was gaining weight. Come on! I started having an incredible thirst all the time, so I went to the doctor. But all my numbers were normal, with the exception that my cholesterol was high.

Long story short, I stopped training for the MS150. I had done something wrong. The thirst went away 10 days after I had stopped training so hard. I had all the data and charts in hand, but I could not explain what happened. In all these rides my average heart rate would run around 150 to a 165 beats per minute (bpm). I calculated my maximum heart rate by subtracting my age (39) by 220. So my max heart rate should have been 181 bpm.

And if you study how heart rate affects fat burning in the body, according to the literature, I was training above my anaerobic threshold. If you train above this limit (which varies for every person) you burn zero fat. There you go—I was demoralized a bit to say the least. I had done all that training, for essentially nothing, and I was feeling bad.


A few months went by. One day around September, 2013 I had blood work done at the doctor. There he dropped the D bomb. My A1C glucose had steadily increased throughout the years, and my cholesterol was only controlled by using statins. Furthermore, I had low testosterone. He told me that if I did not reverse this, I would have diabetes in a couple of years. That was a shock. I had a lot of science working for me, but unfortunately I had waited until the last minute to do something with it.

That’s when I saw a seminar by Dr. Pamela Peeke who was speaking about sugar addiction and the sitting disease. Also, at that time, my niece came to live with us. She was doing the paleo diet. I have to say, I was very skeptical when I heard about it. Reading her material got me to ditch sugar and processed foods. Then, while I was researching the paleo diet, I came across The Primal Blueprint. After reading the book and hundreds of threads on Mark’s blog, it sank into me: I had to try this.

mauricio afterI started in October, 2013 at 217 lbs with 32% body fat. Today as I write this, I have achieved a weight of 180 lbs and my body fat hovers around 14 to 16%. So how did I loose all that body fat and overall weight? Dr. Peeke’s book, The Hunger Fix, convinced me of the real sugar addiction and how my brain was hooked on sugar. Her 3M approach (mind, mouth and muscle) made a lot of sense. I had to work on my mind first. The Primal Blueprint showed me the path to proper training and nutrition. These are the things I did:

1. I went full primal/paleo cold turkey from day one.

I started eating meats, vegetables, nuts and fruits. Between my wife and I, we researched a lot of recipes. It’s amazing the amount of information out there. There are a lot of folk that publish recipes on Instagram, which is an excellent source of information. I used almond flour, coconut flour, ghee, coconut fat, avocado oil, honey and so many other ingredients.

2. I stopped hard cardio completely.

That meant no more long hard mountain biking sessions. If I went for a walk or light jog, I would pay attention not to go above 145 bpm.

3. I started riding my mountain bike at a lower heart rate (115 to 130 bpm) for hours—sometimes five hours at a time.

Instead of doing mountain biking trails that required a lot of effort that spike your heart rate, I started doing easier trails and riding on my neighborhood paved trails. This also required that I ditch my mountain bike buddies, but only for biking activities, after I realized that as a group we would push each other a lot, which would give me high heart rates.

4. I started doing TRX for strength training.

Suspension training is an excellent way of building the core without going to a gym or buying lots of expensive equipment.

5. After five months, I incorporated sprinting.

That seemed to jolt my body to go the extra steps to approach top fitness. I was stagnating around 185 lbs until listening to one of Mark’s podcasts that inspired me to start sprinting. It does have a reaction overall, which speeds up fat burning and make you feel stronger.

So there you go—that’s my story. Don’t wait until you get punched in the face by a doctor’s diagnosis—or worse, have a heart attack. If you have excess body fat, you need to attack that now. Define your present, accept it, move on and do it. I thank Mark for making this information available. This program changed my life forever and I am grateful.

PS: Today I’m off statins and testosterone medicine. All my values became regulated when I dropped all the fat. Plus, my heart rate has dropped around 15 to 20 bpm for the same exercises I used to do when I was overweight.



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88 thoughts on “How Not to Train for an Endurance Event”

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      1. Mauricio,

        I too am having trouble losing fat (currently about 30%). Up until about six months ago, I was working out hard on the treadmill and lifting weights. Was not losing any weight, and not gaining muscle. Stopped intense cardio, and now gaining some muscle, but not losing the fat. The only thing left to do (I think) is getting off the other carbs!

        How did you go cold turkey? I had quit sugar several years ago, and got off statins, but am having trouble losing the fat. I have been trying Primal just recently, but am having trouble going all the way because of cravings, especially in the evening.

        How did you do it? Thanks for the story!


        1. Hi Lew,
          Thanks for your comments,

          Good question about the cravings.

          I think I had cravings for a couple of weeks until:

          1. As Pam Peeke states the sugar high is a LIE that your brain feels and interprets as a reward.

          2. Then if you read the primal blueprint you will find the KORG example on diet.
          I think that’s what made it possible for me.
          By seeing the korg’s diet numbers you realize that he needed to eat around 75 gr of carbs, 100 of protein and around 120 of fat if I remember correctly… Please check the example.

          From listening to Mark’s podcasts you are retraining your cells to burn fat.
          So when I get a craving I have a tbsp of almond butter, that simple..

          Today the most weird things happen. I can go for hours sometimes and realize I have skipped lunch. Just because I had almond butter and cocoa snack at 11 and then got in the zone at work.
          Suddendly it is 3pm, and I say what happened??? Missed lunch….
          So I go by hunger these days.

          Hope this helps,
          I made a quick video to explain how I made the mistake of training hard


        2. Thanks for the response. I will try that the next time I get cravings (Probably tonight!).

          Thanks again.


    1. Thanks for the feedback
      You are right, there has to be something on the engineering mind that propels you to try to base actions on logic. Or just apply the scientific method from biology 😉

  1. Love your story! I’m currently an endurance athlete and have noticed my body fat has gone up since I started running marathons 2 years ago. I don’t want to give them up, but I would like to get my body fat back down to what it was before I started running so much! Primal is hard for me to follow since I’m a vegetarian.

    1. hi Erica,
      Thanks for your feedback. I’m not sure in your case what could be happening, but on mine it was clear.
      When I did my VO2 test (to find out my anaerobic threshold), that’s when I learned that if I pushed above 150 bits per minute all the calories I burnt would come from stored glucose on my muscles.
      My VO2 curve even showed me that at 130 the split was 50% / 50 %, meaning 50% coming from fat the other coming from glucogen.
      May be take a good look at your heart rate when you are training and which zones you stay in.


    2. You might want to take another look at why you need to be a vegetarian.
      I have been a vegetarian off and on over the years and was full on (mostly raw) vegan for three years before switching to Paleo. I have still have my green smoothie in the morning but now follow it with bacon and eggs.

      1. If you don’t mind me asking, what made you switch from vegan after three years?

    3. Erica, I, too, run marathons. Pre-Primal, I was about speed, but now I run slowly and enjoy my surroundings. The marathon high is still there, but now “What would Grok do” is a part of the run. It is definitely a trade-off, but worth it for me.

      1. I just ran my 3rd marathon last weekend (day after my wedding!) with my new husband and we crossed the finish line in 5:15. It was all about just enjoying being out there and it was SO much more fun that way!

        1. Congratulations!! I met my husband while out running 22 years ago!! He enjoys walking these days, but I still love to get out and run. My goal was to always be able to get into my wedding dress on our anniversary. So far, so good!! Enjoy your new life adventure!

  2. Great story! There seems to be a little too much fear about pushing too hard on the bike now. The other week Mark posted about the mile being a great primal exercise as well as diagnostic that stays pretty anaerobic despite some high aerobic demands. I would kindly say that you can not only push hard on the bike for say up to 4-5 minutes even and then ride slow for a whole like intervals (up and down hills of a mountain bike are great naturally for that) and also perform sprints on a bike as well. Nothing compares to sprinting via running, but for some people a bike is safer and makes more sense (not saying for you). Soccer players for example run intermittently for 90 minutes sometimes but dont seem to have the same issues and distance runners. And carry far more muscle mass. Either way, amazing job and great transformation.

    1. hi Mat,
      Thanks for your reply.
      I would say this is a touchy subject since now I know what continued high hear rate can do.
      What I’m doing these days when I push it on the trails is that I go to exhaustion for 30 or so seconds. No more than 5 or 6 times.

      Then I try to keep it moderated around 140. Below anaerobic threshold (that I think should be up by now).

      With the eventual small hill or complication that would spike my heart rate up again, but for a few seconds only…

      Sometimes I rush through a trail and realize that I’m in the zone and have been at 165 for a while…. That’s when my watch beeps… Reminding me that I’m not 20 anymore 😉

  3. Week after week, another beautiful testimony to the power of this lifestyle. Such good results in such a short time. Mauricio, I hope your story today provides the impetus for at least one new person to make the change. Today. I hope they remember you and have equally good results. Thank you.

    1. hi John,
      Thanks for your comment. It was and it continues to be a great discovery ride.
      Grok on!

  4. Nice to read the analysis and how your thinking evolved. Good work and may many others follow your lead. The hardest thing is to have an open mind after all the years of contradictory (non)information.

    1. hi,
      Thanks for your comment.
      You are right. The first thing to conquer is your own mind and be open to try new things

  5. As an avid Mt.biker myself, I really enjoyed that read. I’ve been lurking here in MDA and doing this Primal thing since January 1st 2013. Cliché, I know, but unlike many NY’s resolutions, this one didn’t diminish and disappear after a few months.

    I’ve never had a weight problem, but took up this Primal ‘challenge’ because I read Grain Brain, by David Perlmutter. What I read there made sense to me. Anyway, without writing my own Friday Real Life Story here, I wanted to tell readers about my husband who was, three years ago, told by his doctor that he had high blood pressure and that he might as well start taking medication because there was only one direction that it would go; up. Nothing much you can do about it.

    We are both very active and fit – he, extremely so. I would guess about 12% body fat. High blood pressure was a bit of a shock and almost an insult. How could it be? Super fit, consumer of lots of fruit/veg (and starchy carbs), only a few processed foods. Picture of health. How could it be?

    Anyway, he decided to cut salt out of his diet as an alternative to starting medication. He was a potato chip monster and I like salt, so my cooking included lots of salt (naturally harvested, unprocessed sea salt, but salt nevertheless). He was careful about avoiding it for two years and monitored his blood pressure at least weekly, if not daily. He did manage to reduce his 137/90 average by a few mm Hg, but it was still borderline high.

    Welcome to our home on Jan.1 2013; Primal diet. One year later his blood pressure is consistently 120/80. With NO OTHER lifestyle changes.

    I’m looking forward to hearing what his doctor has to say about it.

    I love this blog and I check in every day. I have learned much and feel that I’ve found my cohort. I’m gratified when I read that my marginalized (by the C.W’s) dietary choices are backed up with studies and, best of all, real life proof: my husband’s blood pressure story.

    1. hi and thanks for your feedback,

      I have to say that recently I tried hydrostatic body fat testing and found out I was at 16%.

      It’s great when changes in diet and exercise allow you to drop medications.


    2. There is a known link between hyperinsulinism and high blood pressure. Elevated insulin signals kidneys to hang on to sodium. From there, if you also intake more sodium while your insulin is elevated, it just drives up your BP.

      (Conversely, elevated insulin dumps magnesium, one reason people with prediabetes and type 2 are short on that mineral.)

      The insulin-BP link even explains why more black people get high blood pressure and kidney problems. They are more likely to have insulin resistance than white people are. I happened to read about that in the process of learning this other stuff and it was kind of an attention-getter after having heard all kinds of other crazy theories about that.

      I wouldn’t expect a person eating Primal and also eating loads of safe starches to necessarily have their BP under control if they also have insulin issues, but nearly everybody else drops their carb intake when they go Paleo or Primal, just by dint of having dropped industrial junk food.

  6. Hi Mark,

    Great story.

    So the engineer in me (EE) asks: Why don’t you put some of your charts on the web with comments.

    For us measurers :).

    You might check out the book “The Pulse Test” (free on the web) and maybe compare some of your numbers with his ideas.


    1. hi John,
      Thanks for the feedback

      You gave me an idea. May be I need to make a short video collague of charts and quick tables showing the numbers and put it somewhere..


  7. You gotta love a success story. Congratulations.

    I’d be curious as to how much alcohol the guy pulled back on because that sure looks like a Margarita on the table.

    Plus: ‘I started riding my mountain bike at a lower heart rate (115 to 130 bpm) for hours—sometimes five hours at a time’. That alone knocks out 2680 calories at 10-12 MPH. (3500 calories equals a pound)

    Calories in Calories out. Better food. Exercise. It all adds up to a healthier person.

    1. hi Butch,
      Thanks for your feedback,
      LOL about the glass, you almost nailed it.
      That’s how I used to think in the past, if I pushed it, all the calories burnt during biking would be drawn from fat…
      So 3500 calories equals a pound.
      That’s only true unfortunately when your heart rate is at super low rates… So walking at 105 BPM, my VO2 curve would tell me I would burn 80% from fat.
      In one hour of light walking I burn around 300, 80% of that is 240 calories (300 x 0.8)
      If I assumed that I can continue that for hours, then I’d need to walk more than 10 hours….. (3500 cal for fat / 240 fat cal per hour)


  8. Great story Mauricio,

    You have convinced me to modify my training habits and shoot for a milestone weight and commit to a 100% paleo self experiment. I hope to submit a similar success story around March 2015

    1. I was hoping one person would act on Mauricio’s story. Looking forward to reading your story next year.

      Who’ll be next?

      1. Thanks John! Now I have your encouragement to hold myself to it. I’m starting by digging up a “before” picture and fixing it to my fridge.

    2. hi Jack,
      Thanks for your feedback.
      I congratulate you for taking that step.
      Although weight is important, it took me a long time to shift my view towards fat content in my body.
      That’s the biggest paradigm change in my opinion.
      Weight alone is meaningless, now by dropping fat total weight comes down 🙂

      1. I agree weight is not the issue. The objective is replace excess visceral fat with muscle mass

    3. hi Jack, thanks for your comment
      And congrants on making that decision.
      I will be there God willing commenting on your story
      Cheers and grok on!

    1. Hello and thanks for your feedback.

      I was amazed by the results I got.
      Following Mark’s advice on the 21 day it’s very clear:
      Lift heavy things, walk or ride a bike at a normal pace for long periods of time, sprint every now and then for very short bursts…

  9. What were your T levels before and after treatment? I have been on them for about 3 years and would like to get off, but the doctor tells me my body will not rebound and start reproducing it at sufficient levels.

    1. hi Eric, thanks for your feedback
      Not meaning to dispense medical advice since I’m not a doctor.
      Before was really low,,, (less than 150)
      After it has been between 700 to 800.
      In my case I’m thinking once I lost the body fat and got of cholesterol medication that did the trick

    1. hi Jeff,
      thanks for your feedback.
      yes it’s good to be off them.

  10. Great story, Mauricio! I confess you lost me with the 32% thing, but it made me think that you should write a book and call it:

    “Primal Numbers: The Engineer’s Guide to Paleo Living”. 🙂

    1. Hello,
      Thanks for your comment,

      Sorry for the 32% thing….. I don’t know how to explain percentages in an easy way without drawing a pizza 😉

      Thanks for the idea on the book. Sometimes I wonder how something like that should be written.
      Let me know if you have any ideas on how it should be approached

      1. My husband is an engineer, too, and when he starts talking numbers, I tell him to draw me a picture, or explain it through interpretive dance. (Just joking about the dance part!)

        If you’re serious about the book, drop me a line at my website email, and I would be happy to throw some ideas your way.

        1. Thanks again for the push and help.
          Not sure about the book since I think I can explain the entire thing in 3 pages. I want though to record a short video explaining my vo2 chart and how that pushed me to train at a lower rate. Coupled with the table showing the drop in muscle mass.
          Hopefuly that can be an a-ha moment for others

  11. Great story Mauricio! I liked the illustration of body fat percentage into an actual weight – very sobering!
    As a mountain biker I’d have to agree with the earlier poster about not fearing the HR spike that harder trails can give, especially now that you’re at a great weight.
    I love love love my weekly ride in the bush which take me to more natural areas than many flatter trails and the technical interest and challenge puts me into a flow state.
    Maybe re-visit those trails with some easygoing riders?

    1. hi and thanks for your feedback,

      I know what you mean, sometimes when I’m pushing through the trails and jumping above roots and dodging branches, I get lost in the rush. It’s a great rush of adrenaline indeed.

      The thing that I find hard to continue doing is to push those sprints on the bike for long continued durations of time.

      2 years ago I did not care, but today with all this information I know it’s not good for me, even if the rush is real and awesome.

      What I’m doing, as you say, is not being afraid of the spikes but when I hear my watch beep at 170 I know I need to chill until it goes to 140 or so.

      Problem is that mountain biking on hard trails can make your heart rate be at 160 to 180 easilly if you are pushing it.
      This is an awesome topic I think.
      How to balance the need to get out in nature and get that rush of hardcore riding?
      I guess balance is the key
      Any thoughts on this?

  12. Boy, did I need this story. Emotionally, I hit an all time low today after running into a very fit friend that I had not seen in years, exactly the type of person I am humiliated to see at this weight. I Iiterally would have hidden if I could have so my friend would not see how fat I am. felt like crying until I read your story. I must start Primal for good, today. Thanks, Mauricio.

    1. hi Leslie,
      Thanks for your comment.
      I congratulate you for having that ephinany (a-ha moment) and wanting to do something about it.
      It’s easier than what it looks, get on the 21 day challenge and try it out.
      Use myfitnesspal to journal your food
      Best of lucks
      grok on!

  13. I like the “water in the bag” thought. Yes, try carrying all that around! Good job Mauricio.

    1. hi Vanessa,
      Thanks for your comment
      You are right, it’s very graphic when you carry the plastic bag with your hands and your arms feel the weight. Mind boggling to think my spine was carrying all of that

  14. That is a great story but what I really like is the jacket…Go Texans!!!

    1. hi Mike
      thanks for your feedback,
      Go Texans indeed 😉 grok on!

  15. Saludo, Mauricio! Bien hecho!

    We have several things in common. No, I am not South American, but I did major in Spanish! And no, I am not an engineer, but I am an attorney, and (according to some) I can be overly analytical 😉 … Anyway, I love data too, and I enjoyed your success story. I agree with another post, some of your charts might be helpful to those of us who make and like to view data graphically.

    I am also a Houstonian (go Texans!) and a cyclist. I have done three MS150s, plus Bike Around the Bay and a week long, 564-mile bike ride (in upstate NY, VT and NH). And, I used to teach spinning several times a week. And, with all of that cardio, I was 10 lbs heavier than I am now. In fact, when training for (and actually doing) the 500+ mile bike ride, I gained weight because I was soooo hungry all the time! And, I got really nauseated drinking Gatorade (high fructose corn syrup anyone?) Gu too – yuck! That was all before I discovered Mark’s Daily Apple.

    Two and a half years ago, I found Mark’s Daily Apple … I am now 51. I am 10 lbs lighter, weighing what I did from age 17-40 (pregnancies excepted). Now I walk occasionally, sprint occasionally, and do yoga several times a week. Those activities do not make me feel like I am starving all the time (of course, keeping primal/paleo/lower carbs helps that too).

    I have only done a few longer rides since going primal/paleo, and I had no issues not with loading up on all the carbs I used to think I had to eat. I look forward to cycling more one day, and I look forward to seeing how my body can handle longer rides w/o all the simple sugars and complex carbs. I think it will do just fine!

    Sorry to turn this into my mini success story. I am glad you have your wife and niece on board! I am still trying to convince many in my family (all with obesity, diabetes and heart disease) to give paleo/primal a try.

    1. HI Melanie, thanks for your comment.

      I really enjoyed your story, you are right, we have things in common. From what you tell, it looks like you underwent a similar process than mine.

      Hard training then bad results, lower training coupled with proper nutrition better results. So simple.

      Keep it up

      1. Thanks, Mauricio! I’ll check them out tonight (no Youtube at work). Melanie

  16. Hi Mauricio loved this story. I like to delve into all the number crunching but like simple solutions! if you want ideas on how an engineer turns stuff like this into a book read Katy Bowman. She has written several books- she had a blog and has a website about restorative exercise. I think Mark has featured her. She is an engineer who looks at how the ‘structural’ engineering in the body affects all our systems – and she is hysterically funny

    1. hi Claire,
      Thank you for your comments,

      I’m not sure about writing a book since I can tell this story in 3 pages, well at least the gist.

      I’ve been thinking on following some advice here and publish some sort of short video explaining my charts and tables. Keeping it short though… I guess nobody wants to watch a 5 minute video on how to interpret a cartesian plot.

      Thanks for the link to Katy Bowman, I will check her stuff out.


  17. Mauricio. What a great success story!!! Congrats on turning your health completely around. Would love to hear some ideas on what you and your family eat now!

    1. hi DJ,

      Thank you for your feedback,

      Well, it’s a good question.

      I’d say that we stay very close to paleo. Definetely no bread, refined carbs, cookies, etc. These days if I have something with wheat on it I feel really bad.

      We have eggs, ham, chicken, bacon in the mornings.
      Then snack on almond butter
      Then lunch chicken, meat, fish with brocoli, salads, etc
      Then snack or no again
      Then sometimes we are not hungry for dinner
      If we have dinner usually is a piece of chicken or a simple salad.

      Lately I’ve been playing with being in ketosis for a a few weeks and that seems to burn extra fat.

      Hopw that helps,

  18. Thanks for doing the calculations. I have now discovered I need to lose 5 pounds of fat to get to my desired body fat %. It doesn’t sound like a lot but I have been at a good weight for my height (5’7″) for a while now and I can’t get my body fat % where I want it. It’s frustrating! Sounds like I may need to incorporate more strength exercises than I already do. Those last few pounds are always the worst though!

    1. hiJeanne,
      Thanks for your comments,

      You are right, for some reason the body likes reaching a state of equilibrium (like Mark states on his book) and then wants to stay there. Different for everybody.
      Mine decided to stay around 180 lbs and 16 to 17% body fat.
      Don’t loose faith, I’ve been trying to achieve 12 to 13% body fat and I realize it will probably take some time… 😉


  19. Great story! I just love Friday’s and read a new life adventure. Since I became Paleo/Primal, I not only watch what I eat; I also watch what I feed my mind (GI/GO). That is why this blog is such a treat, So much to learn and so many new adventures. Thank You Mauricio!

    Today, I have learnt that training over your anaerobic threshold does not burn fat. Now, I can’t wait to inform my buddy who sweats like a hog on his elliptical and is going nowhere fast, much like a hamster (and despairing that the only fat that is moving – is him). .

    1. hi Robert,
      Thank you for your comment,
      Glad to hear you understood the AT dilema (anaerobic threshold).
      Believe me it took me years, it’s completely un-intuitive, at least for the folk of my generation (70’s) that were tought that harder is better, pain is weakness leaving the body, blabla…

      Now when my buddies ask me, what did you do??

      I answer, just walked and ate right…

      But a lot of my friends can seem to escape that illusion of thinking harder is better… Even if thy are in the gym for hours…


  20. I really liked this story because He tells us, Step by step, how he worked his program. Thanks for sharing with us, Mauricio

  21. Love your story Mauricio, although I did feel my eyes glaze over with all those stats! But hey, you very obviously exposed lots of other readers to useful info, and more obviously found the right balance for you – so YAY. We all need to hear information in different formats, and I love your thoroughness. It also gave me food for thought once I figured out how to make it relate to me. So thanks for that too. Isn’t it wonderful to improve your health so significantly by making changes, and not by surgical/pharmaceutical intervention? Keep up the great work. Sounds like you might have a book in you somewhere!

    1. hi Hilly
      Thanks for your comment,
      I know math should never be explained with words…. believe me, I see a lot of glazed eyes at work all the time.

      I’m thinking on doing a simple video explaining quickly the table that showed my muscle mass dropping, leading me to research cellular respiration (aerobic and anaerobic exercise), then finding a VO2 test to find my anaerobic threshold, then just training at low heart rates and following the primal blueprint guidelines on foods

      Or something like that

  22. This is great. From a fellow mountain biker – Congratulations for you successes! You offer a lot of specifics that are great examples to share with the “everything in moderation” crowd. What is your mechanism for measuring body fat? The scales I’ve found appear wildly inaccurate. I trust my mirror more than those.

    1. hi Trip,
      Thanks for your comment,
      You are right about the scales and hand held devices that use electrical impedance in your body to measure body fat percentage. They don’t work…

      I’m using, a simple 4$ pincher… and the mirror test (as you correctly state).

      Back then when I was loosing the muscle mass I was using the pincher and the scales.

      A few weeks ago I took the hydrostatic body fat test that you can do on different place and the result was 16%. The pincher today if I do it on my belly gives me a 15 to 17% so it’s not bad for such a low price 😉
      The scales give me 19 to 20% so I’d guess big error margins when you want to get down into the 12 to 14%

      Hope that helps

      1. Very helpful. Thanks. Ordered a body fat caliper and got it in the mail over the weekend! Confirmed what I believed the mirror was telling me!

  23. Mauricio, great story. I’m also the analyst and track my numbers every time I get a blood draw, etc! We all grew up with the idea that exercise will save us and the harder you can go, the better. I lost 12 lbs when I went primal/paleo. I would love to lose about 10 more but I’ve been steady for a year. I recently started incorporating sprints into my long walks and I’m up about 5 lbs! I hope its some physiological reaction and just water? But I also admit I’m having a horrible time with my appetite and I’m straying into non-Paleo carbs due to hunger. I don’t know whether to continue or drop the sprint quest if I can’t control what I eat. Any suggestions?

    “Don’t wait until you get punched in the face by a doctor’s diagnosis”. Love that and Amen.

    1. hi JJ,
      Thanks for your comment,

      Not sure what could be happening there. But if I understood what you wrote correctly you said incorporate sprints with longs walks.
      On my case when I do sprints I do 5 to 6 sprints of no more than 30 seconds. I do that on a normal 1:30 to 2:00 walk on a forest (park in Houston 😉
      When I do walks or steady heart rate bike rides, I do just that. May be sometime for 1 to 2 hours, sometimes for 3 to 5 hours, depending on how I feel and the weather.
      Now doing that I have not felt a craving for carbs
      I always carry around nuts for trailmix and drink plenty water.

      Listening to Mark’s podcasts I’d been reasearching what could be a good way of measuring cortisol (hormone that propels the body to accumulate fat on the belly from what I’ve understood), since I have a theory that sometimes if fat content starts to climb after exercising to hard it means that cortisol is been generated.

      This happened to me a few months ago when I dumbly followed a mountain biking friend on a week end to mountain bike hard core for 2 hours both days.

      I stopped the activity when I realized that the pincher was feeling a little bit more fat on the abs region.

      Then I went back to normal….

      I keep testing these theories on myself like a guinea pig 😉

      That re-affirmed to me that hard for long periods of time is not for me.

      What I’ve discovered with this stuff is that it pays to write up on a daily or weekly journals what you are doign and what you are thinking, then testing and visiting your assumptions to see if they pan out

      Hope that helps,

  24. OK. Ive been primal for several years. I lost 30+ kg via diet alone. Didn’t do any exercise. Recently starting running (due to BF who does marathons – he’s primal too but has this addiction to running and biking ha ha). I run 5k several times a week (when I say run I shuffle) and have only ever run it once without stopping to walk. I feel unfit, although Ive been running for several months. The thing is I am getting fatter and fatter. Currently 10kg heavier than at my lightest. Is it the running? I am eating slightly less perfectly than before. I probably drink a little too much. But certainly not huge amounts, and mostly spirits (not wine). I am considering buying a heart rate monitor. What should I keep my heart rate at? I am 5 ft 8 and I currently weigh 61kg. Want to weigh about 51kg. I am about to join the gym and do weights and probably run on the treadmill for half an hour (unless you convince me otherwise!)….

    1. hi Jane,
      Thank you for your comment,
      Not sure how can I help you here.
      Not knowing your age I’d say anybody that runs or bikes needs to look at their heart rate.

      Let me explain my case, I took the simple formula 220 – AGE, so 220 – 39 at the time, that’s 181 Bits Per Minute or BPM. That’s the max you don’t want to be above.

      Then in my case (because I did a VO2 teat at lifetime fitness) my anaerobic threshold was 150 BPM. That means above that I BURN ZERO FAT.

      So when I ran I saw my heart rate at 155 to 160 BPM, to high, plus I did not enjoy running. So I never did it (running).

      My suggestion is get a VO2 test done so that you have some valid data for yourself, meaning, if the test tells you that at 160 you burn no more fat, then you know.

      Of course to know your heart rate, you need a cardio frequence meter watch garmin or polar, as you run look at your heart rate, if you are at 260 or above you know you are training anaerobically and will inflict a lot of pain to your body if you do it for long times…

      In my case the VO2 chart showed me that between 115 and 130 BPM, for every calory burned, 80% to 50% would come from FAT.
      So when I wanted to loose the bunch of fat I had it was clear to me that I needed to train low, meaning at 115 to 125 to maximize fat burning.

      The mesmerizing thing here is that at the time if I did a sprint walk I would reach 125 BPM no problem… That was not good. So again, that’s why I trained for long periods of time at a low heart rate

      Not sure if that confused you, try to get the numbers for your case and try it out

      I’m thinking on doing a quick video explaining all these words I jsut wrote with a few pictures and sound

      1. Sorry on the exaple I gave you I meant 160 not 260 as I wrote… Typing to fast 🙂

  25. Hi thanks for that. I will have a good look into things. Went to chiro today and he advised me to stop running also.. so it’s like the universe is telling me to stop! LOL I only run 5k at a time, and have no plans to ever run any further… to be honest.
    I am 43.

  26. Earlier than taking any fat burners, use the ‘Physique Mass Index’ method to calculate
    your fats proportion. This manner you’ll know if the drugs that you’ve got
    been taking actually work or not.

  27. Hi Mauricio,

    Great job. I too am an engineer (electrical/software geek ) so I eat sleep and breathe the numbers.

    Here are my VO2 numbers:

    rate Fat Total CHO % Fat VO2
    (BPM) (Kcal/min) (Kcal/min) (Kcal/min) (mL/Kg/min)

    89 4.1 5.6 1.5 73% 11.7
    90 3.8 5.9 2.1 64% 12.2
    92 5.1 6.6 1.5 77% 13.7
    94 4.9 6.8 1.9 72% 14.2
    100 6.7 9.3 2.6 72% 19.4
    105 6.4 9 2.6 71% 18.7
    110 6.7 9 2.3 74% 18.8
    115 7.1 11.4 4.3 62% 22.8
    120 6.4 9.6 3.2 67% 19.9
    125 8 12.6 4.6 63% 25.9
    130 6.6 11.8 5.2 56% 24.1
    135 8.2 13.7 5.5 60% 28.1
    140 7.7 15.2 7.5 51% 31.0
    145 8.6 15.9 7.3 54% 32.6
    150 8.8 17.5 8.7 50% 35.7
    155 8.2 19.1 10.9 43% 38.7
    160 7.3 20.6 13.3 35% 41.5
    165 6.9 21.8 14.9 32% 43.8
    170 3.9 23.3 19.4 17% 46.4
    172 3.1 23.5 20.4 13% 46.6

    After 150 BPM where max fat burning occurs (8.8 Kcal/min), you can see that the fat Kcal/min drop precipitously and although total Kcal/min keeps increasing from 17.5 Kcal/min to 23.5 Kcal/min, it goes from a 50% fat/50% carbohydrate mix to a 13% fat/87% CHO ratio at 172 BPM. So in my particular case, once I exceed 150 BPM, I am actually burning less fat even though I am working significantly harder.

    1. Hi Jt,

      Thank you for your comment,

      Your post reply is awesome and showcases exactly why this data is sooooo very personal.

      As you can see in your numbers after 150 is still good for yourself and then as you advance the number drops significantly.

      I guess because your fitness level is way better than mine was when I started… Also age might have a play here 😉

      That’s why this test is so important. I’m thinkin on rpeating the vo2 test again and see how I have improved.

      Thanks for sharing this personal data. It drives the point that we all have different metabolisms and need to cater to our own reality instead of following numbers on the internet like: you must train around 70 to 75% of max heart rate to maximize fat burning….


  28. sorry about the table format. I came out looking very different than what I input. But you get the idea.

  29. Hola Mauricio,

    Le felicito! De que parte de Sudamerica es usted? Mi enamorado es del Ecuador, y siempre viajamos alla para pasar Navidad y Año Nuevo con su familia. Alla es obligatorio el tamal a la medianoche del 24, las invitaciones a los tes sociales donde sirven puras golosinas, el mote y el arroz con cada comida (y ademas papas muchas veces). Me encantaria vivir alla unos años, pero comer de forma paleo/primal seria casi imposible. Ni modo!



    1. Hola Laura, thanks for your comment,

      I will answer in English so others can understand,
      I know exactly what you mean about the festivity foods. Complete feast of carbs and refined corn flour.

      What I do when I see friends and family from there is I tell them I can’t eat like that anymore… I eat pork or turkey, with salad and leave all the tamales, hallacas, mote,

      When they ask me to explain I tell them about the D word 😉 and ask if they want to know more…


  30. I found a discrepancy, so I am looking for clarification… In Primal Fitness, Mark notes that our Max Heart Rate should be calculated by 220-age for males and 226-age for females. But on the Primal Endurance book, it is 180-age, in general. Which should we use??
    (Thanks in advance for your help)