What Defines Cardio in Terms of Too Much – Q&A

Question: This is a follow up question for your last QA. It is often said that too much cardio on a restrictive diet is “bad”. With NEAT in mind, I wonder exactly what defines cardio in this setting.  Playing with your kids for a few hours(playing ball in the yard etc) is this defined as cardio? Does taking a leisurely stroll with a baby carriage for an hour or two
per day count as cardio? Or is cardio defined as something else?

Answer: I think you’re referring to the article I wrote on Why Big Caloric Deficits and and Lots of Activity Can Hurt Fat Loss, although I may have addressed the issue in a Q&A as well (I can’t find it).  In any case, your question is one that comes up fairly frequently, especially in the context of the Rapid Fat Loss Handbook approach (where I am adamant that excessive activity/cardio can cause the diet to work far less well than expected).  People want to know what and how much of certain types of activities will or won’t cause problems.

The primary issue here is this: the body appears to be sensing what researchers are calling energy availability, basically energy in (from food) versus energy out (via energy expenditure as discussed in detail in Metabolic Rate Overview).  And if energy availability becomes too low, often bad things (in metabolic terms) happen.  For example, researcher Ann Louckes has shown that many of the issues that often occur in women in terms of hormones or menstrual cycle dysfunction occur at a threshold of energy availability (and aren’t actually related to body fat percentage as used to be thought).

In that sense, pretty much all activity can potentially be a problem if that activity results in an energy availability to the body that is too low.  Of course the activities you’re listing aren’t really big calorie burners, a walk with a stroller probably only burns a few hundred calories per hour.  But done for extended periods it will contribute.

A related issue, and one I focused on more in Why Big Caloric Deficits and and Lots of Activity Can Hurt Fat Loss can be related to both intensity and volume.  In addition to hormonal issues, often the combination of big caloric deficits and excessive activity (either too much activity, too hard of activity, or the combination) can cause some real weirdness with water retention that masks fat loss.

I’d tend to say that this is more common with more formal ‘cardiovascular’ activities than just activities of daily living.  This is just due to the potential for increases in hormones like cortisol; this is especially an issue as the intensity of activity increases.  Clearly this isn’t an issue for a leisurely walk but it becomes more of one for more formal cardio activities.

This isn’t really stopping fat loss mind you, but it does drive people crazy because it makes it appear that the diet is not working.  I’d note that this isn’t an issue for everyone, certain physiologies (and especially psychologies) seem relatively more prone to problems with water retention than others.  This is why some people can get away with massive amounts of activity and not have issues and others can’t.

In any case, I hope that answers your question to at least some degree.

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12 thoughts on “What Defines Cardio in Terms of Too Much – Q&A

  1. Isn’t to some extent, exactly what The Biggest Loser folks do? Restrictive diet in the 1k-1.5K calorie range, and then extremely high volume, low-medium intensity cardio for hours and hours? Essentially burn 2K or so cals in 4-5 hours of various stupid cardio activities and be 2K or so under Sedentary maintenance calories with their diet? Trying to make a 3.5k+ deficit every day?

  2. Great article Lyle! Through my own experiences, I think for me, assuming only a moderate deficit (500-750 kcal/day), leisure walks (16-20 min/mi.) are great for increased energy expenditure, mood, and overall clarity. I haven’t seen any negative effects 1-2 hrs/day.

  3. Lyle, I’v read the article about big calorie deficits and lots of activity. Now, I’v been on the Rapid Fat Loss plan for about two weeks, then this weekend I had a massive binge. I was away from home, had no access to healthy food, and ended up eating at McDonalds a couple of times aswell as drinking a lot of beer. I definitely ate a couple of thousand calories over maintenance. (Protein intake was a least adequate though)

    In this case, is it ok to go back to the RFL diet again and do a lot of low intensity cardio for the next couple of days. Won’t I just be burning off the excess calories still in my system from the weekend? As long as the only problem this causes is water retention I can deal with that. It’s only temporary anyway. (I’m about 15% bodyfat by the way, taking in LBM x 2g of protein per day)

  4. Jared, the propsed threshold is 30kcal/kg Lean body mass per day availability for biological function (i.e. after training expenditure is accounted for), often discussed along with female athlete triad. Loucks is the main researcher


    worked examples here


  5. Dan: Yes, this is what the Biggest Loser does. A couple of things. Extremely overfat people often get away with things that shut down leaner individuals. The BL contestants are at a real extreme of obesity. I’ve addressed other issues in that group elsewhere on the site.

    As well, the sheer amount of exercise done can often compensate for any metabolic negatives that occur. That is, it’s one thing when someone is doing a couple of hours/day of activity and this gets overwhelmed by whatever metabolic events occur. But by the time you’re at 8+ hours of training per day, you simply overwhelm it. But that’s not realistic for most people.

    That is, just looking at those two issues, usually folks I run into having problems with the ‘too much activity + too large deficit’ are
    a. towards the leaner end of things
    b. not doing nearly the amount of high volume/intensity activity on the show

    Finally, there are at least a few cases on the show where a given BL contestant was limited to much lower amounts (volume or intensity) of activity . I can recall one where an older gentleman had a heart issue. He was limited to much more reduced activity levels with the extreme caloric deficit. He lost more weight than anybody else.

    I think there might be a lesson in there somewhere.

  6. Good info as always! I have noticed several times that after periods of hard training I’m extremely hungry and crave for carbs for day or two, but after few days of recovery or lighter training I feel fine. And even when the energy deficit is kept constant (e.g. -500 kcal/d). I feel that when tired fat oxidation is somewhat decreased and body relies more on carbs. This would make some sense as in sleep deprived the use of fat for fuel is also decreased. Any thoughts?

  7. If the issue is with cortisol, could I be stimulating the same problems by having a lot of coffee and fasting throughout much of the day?

    I don’t do much activity but I don’t have a car and my job requires me to stand up and teach children.

  8. Hi,
    Maybe that is what is wrong with me! Training for triathlon, doing lots of cardio, but trying to be careful with what I’m eating, always tired, but I’m not losing weight, slight indulgence and the weight goes on, Should I be eating more foods to give me more
    energy if training hard to stop the fatigue and aid fat loss. Trying to find a happy medium where I can train hard, lose some weight and not be so tired. Mind you work 60 hours a week too might not help.

    Maybe I should read the SFL book again.

    thanks, craig, Sco / Uk

  9. Lyle with all you have wrote it still unclear to me how could i know the safe range for cardio without getting deminishing returns. Any guidlines for folks to know what considers too much (e/g 6 time a week easy-medium intensity) would be the highest range or something similar. What cardio range (duration/intensity) would you suggest being safe and reasonable? Where is the line that separates fine and too much of it?

  10. It depends entirely on how much you’re eating but there is no singular answer. On very low calories, anything over daily activity might be too much. ON very high calories, you can ride the Tour De France.

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