I am sure I would have done this post at some point, but I felt the need to do it now because on Thursday I overheard a trainer is telling her client that she must do cardio fasted. To not even have a granola bar because then she'll burn the granola bar and not fat.
Puh-lease. So false. Was once a common held belief, and still is by many, but that does not make it right, and, in fact, it has long been and continues to be debunked.
Performing cardio fed = good, performing it fasted = potentially detrimental.
People need to keep up-to-date in their field. They need to be relevant and provide correct information. Keep reading and researching, always. I get really, really frustrated by what I hear trainers and nutritionists say, and this is just the most recent (as opposed to the worst offense).
I read several articles and studies on the subject to back up my own thoughts, and also focused on three of the big bodybuilding guns: Alan Aragon, Layne Norton and Lyle Macdonald.
The idea behind the fasted cardio myth is that if you work out in a fasted state, your glycogen levels will be low, forcing your body to burn fat, not carbohydrates.
The truth is, while you might burn more calories, you really won’t lose more fat, and you’ll also increase cortisol levels, leading to muscle loss, which obviously is far less than ideal. Fasted cardio is especially common among those cutting or trying to lose weight, but that is when preserving muscle is even more important.
You can eat carbs at any time, even at night, as that study in a recent post concludes (and many of us have long known at least from personal experience, if not research), but it especially makes sense to eat them around the time of your workout.
Eating carbs prior to low intensity cardio reduces fat oxidation but does not do this when workouts are done fasted.
There are mixed results during moderate-intensity workouts. Basically, food is beneficial for untrained athletes, but for trained ones, there does not seem to be a reduction in fat oxidation for the first 80-120 min of exercise.
Carbs also help protect against metabolic stress, which is not the case in those who perform fasted.
One of the studies Alan Aragon found looked at people who worked out for 2 hours at the point of maximal fat oxidation during exercise, and found that those who ate carbs pre and during working out had an increased performance and there was no difference in total fat oxidation, availability, or utilization.
Likewise, in a study of February this year, once again, fed athletes showed no difference in fat oxidation. This study examined endurance-trained athletes working out having carbs, carbs and a placebo, or a placebo alone at various times before and during their cycling.
In sum, having carbs before working out does not affect or prevent the breakdown of fat, and eating increases muscle glycogen and often increases performance, at least in low intensity workouts.
My bottom line is that pre- and post-workout nutrition is important (NB some knowledgeable folks think this is overemphasized, whereas I disagree). Cardio should not be treated differently than lifting in that you should have enough fuel to maximize the efficacy and performance of your workouts. Play around with what you eat and when you eat it. Personally, I like a full meal an hour beforehand (I usually work out after meal 2, as posted in my first blog entry), but you might prefer a smaller snack, such as a banana with nut butter or a serving of oatmeal with walnuts, closer to your workout. You want to have energy, be able to digest your food, and not feel weighted down. And as for when to do cardio, it does not have to be first thing. Do it whenever it fits into your schedule and you’re likely to make it a routine.
And, PS, fat loss really is not about cardio at all. Diet and calories in vs calories out and macro’s are number one by far, followed by a good lifting routine. Cardio is an accessory.
randi morse, randi.morse@gmail.com, newton, ma
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