Pre-Workout Feeding Myth - You Need Food for Energy Beforehand
May 22, 2008
photo by kenmccown
Continuing along with our discussions on feeding and working out, I once again came across another good article by Ori about eating before a workout (or not):
Diet Fallacy #2. EATING BEFORE EXERCISING will provide your muscles with instant energy
Many people assume that the human body operates like a machine and therefore in order to work, it needs to be fueled liked a machine. Eating before exercise seems to make sense. But does it really?
As you’ll soon realize, the idea that pre-exercise meals provide the muscle with instant energy is literally wrong, often misleading and counter effective.
In order to provide the muscle with nutrients and energy, food must be first fully digested. During digestion food is broken down into smaller compounds, yielding molecules of amino acids, fatty acids and glucose – which are transferred to the body’s tissues through the circulatory system. The digestion elimination process, that occurs in the stomach, intestines, liver and kidneys, respectively, requires substantial amounts of energy. During digestion, blood flow shifts from the brain and muscles to the inside organs (responsible for digestion and elimination). That shift in the blood flow profoundly affects the brain and muscle tissues, lowing their capacity to perform and resist fatigue.
The question remains: “What about meals that require almost no digestion?” such as those made from fast assimilating nutrients. (Note that fat is a slow digested and assimilated nutrient compared to protein and carbs.)
Consuming a pre-exercise meal made from a blend of fast releasing proteins and carbs (such as whey and sugar), looks initially quite appealing. In theory such meals would nourish the muscle tissues with amino acids and glucose to inhibit muscle breakdown, while providing instant energy. It all makes sense, but even so, in real life, things often work differently than in theory.
Recent studies demonstrated that eating fast releasing foods before or during exercise could be counter effective, to say the least. Investigators in the school of sport and exercise science, University of Birmingham, Edgbastion, England found that ingestion of carbs before exercise adversely elevated plasma cortisol levels. Interestingly enough, there was a significant reduction in post exercise cortisol when carbs were not ingested before exercise. Furthermore, there was a faster shift from carb to fat fueling during exercise, when a pre-exercise meal was not applied.
As for protein, what failed to reach mainstream nutrition knowledge is the already established fact that protein rich foods raise cortisol levels if applied incorrectly. Studies at the University of Lubeck, in Germany, found that oral administration of fast releasing protein foods such as hydrolyzed (pre-digested) proteins, have an even more profound cortisol elevating effect, compared to whole protein foods.
Note that chronic elevated cortisol has been associated with muscle wasting and fat gain (in particular abdominal fat.)
In summary, pre-exercise meals may rob the brain and muscle of energy (due to digestion). Eliminating the digestion effect of pre-exercise meals may only make things worse. Eating meals made from fast releasing proteins and cabs, before exercise, can cause a profound cortisol elevating effect during and after exercise. This may severely compromise ones ability to build muscle and burn fat.
Take home points, obviously working out in the AM fasted works for this. If your workout is later in the day and during your eating hours then don’t worry. Just make sure your last meal was a couple hours before your workout. Remember that our goals are to use up muscle glycogen (so we can replace it along with amino acids to rebuild) and also to burn fat in the period after the workout (if you are waiting to eat 60min pwo). None of this can be accomplished if we are loading our bodies with sugar and carbs before the workout even begins. As you will see in mainstream media, this is not the message you are getting. Look everywhere and you will see Gatorade, Energy Drinks loaded with sugar, Workout Drinks/Bars…..people saying we need energy to workout, when in fact we have plenty….it’s called fat stores!
Does this apply to strength training/weightlifting or cardio? Or both?
Also I like to eat something pwo almost immediately when finishing? Should I be waiting longer? Thanks.
I’m finishing my PhD thesis on carbohydrate ingestion before and during exercise and their effect on fuel utilization and performance. Many points should be clarified but here are just a few…
Taking carbohydrates before or during exercise will spare the utilization of your muscle glycogen and allow to increase performance et duration of exercise by contributing to your energy supply, this is a well established fact. They can also reduce utilization of fats, which is not always wanted in people who are aiming at loosing a few pounds. But the increased intensity that can be maintained during exercise with carbohydrate exercise might favor fat burning to an even greater extent following exercise. Additionally, the higher intensity sustained would allow greater gains in cardiovascular fitness and health.
Carbohydrates in the form contained in Gatorade (~6g / 100mL) is optimal for relatively short duration (2-3h or less) or intermittent exercise. Protein or amino acid ingestion are not important unless you do very prolonged exercise. Now it’s true that taking a heavy meal rich in fats and protein just before exercise might hinder performance, taking energy drinks with simple sugars will increase performance by a great deal and delay fatigue. Not just physical performance but also cognitive performance in tactical sports is improved.
Just my 2 cents…
Stephen - What are you goals? In theory it applies to both as you should have enough stored muscle glycogen for a workout, and most people who do cardio want to try and burn some extra fat. PWO doesn’t have to be immediate esp if your goal is fat loss with muscle building. Cardio, unless they are higher intensity intervals, really doesn’t matter because there is no applicable GH response or elevated post workout metabolism to take advantage of, so have something right after esp if it is longer in duration and has the potential to raise cortisol and lose muscle. It all depends on what the workout is.
Jonathan - Good points. I agree but like most people here, people will do their workouts to try and build muscle/burn fat. While intensity is dependent on muscle glycogen, most workouts only need to be brief and not extended like say a sporting event for hours. For longer bouts of cardio activity (under an hour), we want to burn fat…not gatorade, so there is no reason to even take the stuff. (plus there is still plenty of stored glycogen to utilize for higher intensity intervals). If we want intervals to spike up fat burning post workout, the last thing we want is to drink something that raises insulin (a non-fat burning hormone). If you are recovering enough to replenish muscle glycogen, your workout intensity should not suffer in smaller time frames. If your activity is higher intensity for 2-3 hours, then a carb/protein supplement drink will be advantageous to sustain performance and intensity. There have also been studies to show (the infamous cho milk as pwo drink) that a combination of protein/carb in ratio of 1:4 is better at muscle glycogen uptake than just carb alone.
Again, training or competing at higher intensity for 2-3hours is a completely different animal than 30 min of strength training or intervals/slower cardio for fat loss. So there are exceptions to the rule. The average person however does not need the same replenishment as a professional athlete, which is how gatorade markets their stuff to the average overweight exercising crowd. Just look at the label “Rehydrate, Replenish, Refuel”….that is not going to help Joe “Weekend Warrior” Smith at 20% BF to lose any lbs….and is probably keeping him there too.
Mike, my broad goal is to be as fit as possible. Specifically my focus is on increasing muscular endurance and strength increases in core lifts like the press, deadlift, and squat. I want to maintain my muscle composition and reduce my bodyfat. I’ve gone the route of assuming that doing the first would lead to the second, however I’m coming to the realization that I need to fine tune my approach, especially in regards to my diet in not only what I eat but when I eat. Unless of course I’m overthinking this.
Thanks again.
Good information. So many times I have spoke with people who reach for the ‘Gatorade’ or other sports drink the day they start working out.
Many times, these are overweight people, enthusiastically starting an exercise program, and they see the whole pre-workout snack\meal\drink as part of the equation.
If fast fat loss is the #1 priority, I truly believe the last thing someone overweight should be doing is ingesting calories above and beyond normal daily food consumption pe-workout.
People see top level athletes doing such practices, but must understand that the protocol for top level physical athletes is certainly not the best protocol for people on a general fitness program wanting to burn away some excess body fat.
Stephen - nothing wrong with overthinking diet…as that is where 85% of your weight loss/muscle gain come from. Make sure you also check out the Fat Loss 101 post and Muscle Building 101 post. Getting your hormones right is how it all happens. Just eat enough protein to maintain and build muscle, just enough (which is small) amount of carb to go to muscle glycogen but not overspill into fat stores (whole food versions only, no insulin spiking drinks), and then enough dietary fats to maintain hormone production…all at a small calorie deficit for the day to burn fat. See, not so hard.
You’ll get it down, as seeing how your body responds to food and why is the most important thing you can learn about how to get results. When in doubt you can keep it simple and play with the numbers….protein + veggies + fat all day long….protein + carb (fruit/whole food complex carbs) in the pwo eating window (1-3 hours). People who want to get lean have to learn to cycle and time their carb intake properly, that is the secret.
David - So true. I have to keep telling people who want to lose fat that they are not a professional athlete, do not train like one, don’t burn 7000cal a day and are not at 6% BF….so why are you listening to them? (Not too mention how much they get paid to sell the product too)
Mike, last question I promise. Should I be concerned about calories consumed relative to bodyweight? I have a fitday account and some days I’m only eating 2000-2200 calories. I’ve read that for an active person like myself at 200lbs that this is way too low. Should I be upping what I eat?
Stephen - if you are trying to lose lbs, you have to eat less than what you burn (and I don’t even believe those calculators are close to real world numbers). The golden rule of take you ideal weight and x10, should be the amount of calories you need to eat to lose weight. More important is getting enough protein too, about 1g/lean lbs. The real tricks are low cal days with high cal day cycles to burn fat at less calories….aka IF during the week and don’t IF on the weekend. People who follow those BMR calculators usually end up staying fat. (as I’ve seen some that tell overweight women they need 1800+ calories…which is an insane number to try and really lose fat)
thanks for the feedback Mike, the thing is if i do weights in the AM (fasted) i then eat pwo for recovery etc i am no longer doing IF as i’ve only fasted overnight for 8 hrs or so (like everyone else does every night), so in order to train weights in the early morning & still follow an IF lifestyle i would have to not eat pwo, for getting lean quick this might be ok. I suppose a fair compromise would be a small protein+fruit meal & then continue fasted until later in the day.
JC - Remember that you make IF work for you and your schedule. No reason you can’t eat non-IF on weight training days and IF on non-weight training days (assuming you only lift 2-3x a week). You can make it work for you….as that is the real key to IF, it’s flexible for anyone. Once you start eating it’s a good idea to keep a steady stream of aminos coming in every 3-4 hours as you have broken the fast.
My anecdotal experience backs up this post.
For about 2-1/2 years, I rode my bike about 17 miles to work and back, about an hour each way at moderate to high intensity (~140 bpm av. on an HRM), three or four days/week. That was my only exercise at the time.
Bonking was an occasional (and extremely unpleasant) problem on the rides home in the afternoon, despite the fact that I varied my diet several times to avoid it, based on the idea that I could prevent the bonks by pinpointing just the right kind of fuel to restock my glycogen sufficiently to get me home. I tried energy bars, fruit, half a sandwich, fig bars, Gatorade, trail mix, and probably other things I’ve forgotten…but nothing worked. Abot once every couple of weeks, I’d get about 20 min. into my ride home, and feel dizzy, lightheaded, and completely drained of energy. An energy bar at that point WOULD restore enough energy to get me home, but clearly, eating beforehand hadn’t helped.
Perhaps not coincidentally, my weight increased by over 20 lb. in the months after I started this regimen, from about 195 to just over 220, despite the 8 or more hours/week of cardio on my bike. My diet: very low fat and heavily carb-based, much of it refined. I got the weight back down by following a glycemic-index based diet, but the bonks persisted, and it still puzzled me that I could gain so much weight on a low-fat, high-carb diet.
The only thing I didn’t try was NOT eating before the ride. I ate throughout the day, and tried to have my pre-ride fuel about 20-30 min beforehand. So this post helps me make sense of what may have been happening.
In any case, I’ve been doing IF with a relatively low-carb, high-protein, high-fat diet since the beginning of the year, and am at my lowest weight and smallest waist size in over ten years. Due to core exercises at home (mostly pushups and chinups), I am also the most muscular I have ever been in my upper body.
Oh, and I won’t be going back to those long bike commutes. I don’t think they were good for me at all.
Murray - Great story, thanks for sharing.
[...] Myth of needing food before a workout Jun-6-2008 Posted under Kelly Talk check out this on the whole myth of needing food before a workout for energy [...]
I’d be interested to know how all of this changes for someone with very low body fat levels, say a pre-contest body builder.
Barry - I don’t really know if this is something a precontest BB may do as most carb deplete anyways and then load back up before the show. A person at 3-4% BF is definitely going to be an extreme case though.
What sucks is to realize how many things I’ve been doing that were wrong…based on “science” touted through mainstream media. I just downloaded your Intermittent Fasting Special Report and I am looking forward to learning more and finally getting control of food not controlling me…
Elizabeth - Yes we have all been fed many things, but some of the things can work….but others do not. More than one way to get results. Gaining control and learning how the body reacts is the best thing we can do…that and ignoring most media.