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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