Eat before or after am workout

For me it depends on choice of exercise. If I am doing almost anything cardio, especially anything which involves a bouncing motion (read: running, aerobics), I will get sick if I exercise with anything in my stomach. In other words, I eat after. I am usually fine for non-bouncing motions (most weight lifting, elliptical), but I still tend to not eat before since the very act of working out makes me hungry so I always eat after.

sijomial wrote: »

Jthanmyfitnesspal wrote: »

Watch out, everyone, @sijomial and I love to argue about stuff. We should take it to the "Debate" forum.

@Jthanmyfitnesspal

If your argument is that people need to exhaust their glycogen stores before fat is burned it would be a very short debate!
Get yourself to a sports science lab and they can tell you what your carb:fat ratio is at different intensities from rest to maximal output. Carbs and fat aren't used sequentially but simultaneously, that's a basic physiological fact.
Want the highest proportion of fat to be used as fuel for your body? Sleep will do that for you.

Or simply think about all those people who lose fat without any exercise let alone extreme and long duration exercise.


This is what exhausted glycogen reserves looks like....
(Loss of muscular power, loss of coordination, mental confusion, crushing fatigue....)

https://www.youtube.com/watch?v=liCRrheKIOI

I don't believe it.

He wasn't crawling.

It is interesting effect when some muscles have run out and some haven't. And overall liver must be tapped out almost.
Those guys at their pace though - man, include lactic acid buildup and electrolyte imbalance and dehydrated in the mix too. Yikes.

I've only had effect of mental cloudiness from liver stores getting low and low blood sugar, push through that though and muscles can still keep going.


For OP topic:
For typical morning training I may do, empty stomach is fine for limited time I got anyway.

sijomial wrote: »

Jthanmyfitnesspal wrote: »

Watch out, everyone, @sijomial and I love to argue about stuff. We should take it to the "Debate" forum.

@Jthanmyfitnesspal

If your argument is that people need to exhaust their glycogen stores before fat is burned it would be a very short debate!
Get yourself to a sports science lab and they can tell you what your carb:fat ratio is at different intensities from rest to maximal output. Carbs and fat aren't used sequentially but simultaneously, that's a basic physiological fact.
Want the highest proportion of fat to be used as fuel for your body? Sleep will do that for you.

Or simply think about all those people who lose fat without any exercise let alone extreme and long duration exercise.


This is what exhausted glycogen reserves looks like....
(Loss of muscular power, loss of coordination, mental confusion, crushing fatigue....)

https://www.youtube.com/watch?v=liCRrheKIOI

I hear what heybales is saying, but also . . .

. . . video evidence won't matter anyway.

I admit I've never bonked. I'd bet many (most?) people have never even been at least close to bonking, or probably even close to the "muscles literally *won't* step it up" effect at/near actual max CV effort (that doesn't come close to exhausting glycogen but is IMU more about personal limits of quick delivery and utilization of energy at that time).

Of those without experience, and who've not seen or heard a report of it from anyone they personally know/trust, some may tend to attribute such a performance failure to failure of will (or some other non-fueling factor), still not fully believe in the things that endurance athletes experience (and see in lab testing) about fueling in endurance scenarios, especially long/difficult ones.

It's easy to be deceived via felt experience, IMO, about the underlying physiology of these things: Can't feel fueling transitions (short of bonking), so common sense can mislead.

Most of us (I think) have probably felt fatigue via longer more moderate exercise (with mild confusion, coordination compromise, etc. happening also), that was improved when we ate/drank; that makes it tempting IMO to think there's some linear effect at an extreme, rather than a sudden hard stop eventually, or to think that that lower-level fatigue/improvement is an example of glycogen stores literally completely running out. 🤷‍♀️

Intuition fails, absent experience, maybe, kinda.

andremaza7 wrote: »

I read an article that said if you sleep at least 7 hours the night before that you will be burning fat and if you wait to eat after a morning run that you are extending that time of fat burn. I would definitely drink some Gatorade or something with electrolytes before running though because your body has been without it for the past 7 hour that you slept. I also read that If you sleep 5 hours or less you can actually start burning muscle instead of fat.

Fat is the PRIMARY source of fuel AT REST. Once the body starts moving intently and more physically, glycogen is the fuel first used. Depending on the intensity of the exercise, fat can be burned along with it eventually. But whatever article you read isn't accurate.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

Jthanmyfitnesspal wrote: »

@sijomial: Maybe our debate will evaporate if I say instead that you need to deplete (rather than exhaust) your glycogen stores for your body to burn fat. When you exercise fasted, your liver will tend to create glycogen from your fat stores, rather than from glucose metabolized from food. As I said above, the process is completely reversible, so if you over-eat later, your body will turn extra calories back into fat. (The fact that we can carry so much fat is a human superpower that made us a dominant species. Yay!)

(This is all in my unprofessional understanding. I am a PhD, but in physics, not physiology. I have read a few papers on the subject, such as the one below, but human physiology is a very complex subject!)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019055/

Good article!

But I don't think that's going to end the debate. Even that article makes it pretty clear that lower intensity activity is more fat fueled, and higher intensity activity more glycogen fueled - not so much a depletion model as a transition between energy delivery systems that respond to different demands, and respond at different speeds.

Exercising fasted may shift thresholds of that transition process somewhat, I don't know. But there's plenty of glycogen available in the body to be burned during normal fasted exercise, even upon waking. Sure, if someone goes instantly to high intensity (a bad plan for performance as well as for injury avoidance), the activity quickly becomes more fat-fueled, but that would happen even if not fasted.

I noted, in the linked article (page 29):

The fasting that occurs between meals, during sleep, or even during more extended periods of fasting has minimal effect on muscle glycogen concentration in resting individuals because muscle glycogen is not a major fuel substrate at rest.

We agree that exercising fasted/fed doesn't matter for weight loss (unless individual intensity capability differs because of the fasted/fed state, so that the exercise itself burns more/fewer calories, of course). Performance matters for total calorie burn, of course.

Page 26, note that placebo group:

Little et al.116 studied the effect of consuming a low-GI meal (lentils; GI = 26) or a comparatively high-GI meal (mashed potatoes, bread, and egg whites; GI = 76) prior to 90-minutes of intermittent treadmill exercise. The meals were consumed 2 hours prior to exercise. Compared with a placebo treatment (no meal), both the low- and high-GI meals improved the total run distance during sprints conducted in the last 15 minutes of the 90-minute session. In contrast with no pre-exercise meal, muscle glycogen levels prior to the final 15-minute segment of exercise were similarly higher with both low- and high-GI meals. The authors attributed improved run performance to higher muscle (and possibly liver) glycogen levels prior to the final sprints.

Still, for the average person doing a normal sort of workout, and whose goal is to maximize total all-day calorie burn, exercising fasted or not fasted doesn't matter enough to worry about, IMO. Performance capability (for intensity) may matter, if the person performs better in one state or the other. Even that effect is likely to be small, commonly, IMO.

ETA: It looks like the source for glycogenesis (to replenish glycogen) during exercise may differ depending on circumstances, but digestion is a somewhat slow process. I don't know what effect 8-16 or even 24 hours of fasting would have on the replenishment sources, but in a context where full digestive transit could take 50+ hours, 8-12 hours doesn't seem like much.

But heck, I'm not even a physicist. Only relevant credentials are some coaching education, and to the extent that included fueling issues, it focused on practicalities (the how much of what kind of meals/snacks around competition kind of thing), not the physiological basis for those recommendations.

Jthanmyfitnesspal wrote: »

@sijomial: Maybe our debate will evaporate if I say instead that you need to deplete (rather than exhaust) your glycogen stores for your body to burn fat. When you exercise fasted, your liver will tend to create glycogen from your fat stores, rather than from glucose metabolized from food. As I said above, the process is completely reversible, so if you over-eat later, your body will turn extra calories back into fat. (The fact that we can carry so much fat is a human superpower that made us a dominant species. Yay!)

(This is all in my unprofessional understanding. I am a PhD, but in physics, not physiology. I have read a few papers on the subject, such as the one below, but human physiology is a very complex subject!)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019055/

Repeating some here. And yes that is a very good review article.

Even fasted you have glycogen stores, unless a really long fast (or in keto), you got liver stores, and muscle glycogen stores that can't be put back into blood for use elsewhere and not likely used while sleeping or non-intense non-exercise movements. (even in keto you have stores, but low enough body would rather provide ketones to preserve them)

As that article shows, and anyone getting an RMR test that happens to show the substrate usage, or VO2max test where they for sure do the same (both of which happen to be done fasted if done right) - you start out resting or standing on treadmill (or sitting on the bike) with upwards of 90% fat usage already. (unless a medical issue going on)

No requirement to deplete existing glycogen stores. And to the mis-informed keto'rs, no need to become fat-adapted.

From other research on marathons and recommendations, when starting exercise fasted you can train the body to go quicker to a ratio of carbs/fat it would eventually end at for the intensity of exercise, instead of relying too long on the blood sugar.

So say you did a cardio exercise and your intensity was such you had 40/60% carb/fat usage during the workout, what the body settled on needing. And majority of those carbs from the muscle stores.

But when you started the workout just out of the gate, blood sugar supplied the carbs, and the ratio was say 60/40%. Taking 15-30 min to both settle to ending ratio and using muscle stored glucose. That extra carb usage could be very bad for hard endurance event.

That's how fasted cardio may be useful - if those are aspiration. But still wise to do slow warmup before an actual race, get body to max preserve-glucose mode. Since carb absorption from eating during exercise maxes out, and usually much less than you could be using, so important to preserve what you got stored.

"Maybe our debate will evaporate if I say instead that you need to deplete (rather than exhaust) your glycogen stores for your body to burn fat."
Not true and very easily and repeatedly demonstrated not to be true. Fat (whether dietary or body fat) is being used all day and night long for energy. Lower the activity level the higher the proportion of fat used
Think you would find it absolutely fascinating to be tested in a lab, well worth the expense IMHO as it's very educational for anyone serious about sport/exercise.


"When you exercise fasted, your liver will tend to create glycogen from your fat stores, rather than from glucose metabolized from food."
That would have to be one hell of a fast! People may well have 400 - 800g of glycogen stored (primarily liver and muscles). And whenever they do eat carbs that reserve gets topped up again, but few people will be totally topped out (hence carb loading strategies before endurance events).

"As I said above, the process is completely reversible, so if you over-eat later, your body will turn extra calories back into fat. (The fact that we can carry so much fat is a human superpower that made us a dominant species. Yay!)"
Yes we have virtually unlimited energy stores in fat, we don't tuck away that energy for no reason or because it's difficult to use. It doesn't take any special nurturing to use that energy, you are predominantly using it right now sat at your screen, just as I am. I have to be cycling at about 140 - 150 watts constantly before carbs overtake fat as the main fuel. It's the main reason why long distance cyclists can keep going all day long despite being limited to intaking/digesting c. 60g of glucose an hour.
We have significant but limited glycogen stores which are a precious resource for high intensity exercise and brain function, it's not used up easily but is in a constant state of flux, just like your fat reserves are.


Think about a few scenarios.....
Non-exercisiers losing significant amounts of body fat, just from a calorie deficit over time.
Someone exercising in HR zone 1 or 2 (a.k.a. the fat burn zone), majority of their exercise energy needs met from fat along with a minority from carbs.
People in a calorie deficit but with a high carb diet and still losing body fat, never significantly depleting their carb reserves. (That would be me!)
Pro cyclists eating huge volumes of carbs and still losing body fat down to very lean levels.

corrine9720 wrote: »

Hi there I am just starting out and want to use my treadmill a few times a day is it more beneficial to eat before or after breakfast

I have lost 126 pounds since June 2021.

I seriously weight train in the a.m. three times a week. Before I do, I have two giant cups of strong coffee (half decaf) with 1/4 cup of soy milk in each. I can then power through. I eat a large hi-protein and fibre breakfast afterward.

I do an indoor cycle 3-5 times a week, usually in the evening. I eat a large high-protein and fibre dinner afterward.

The best time to synthesize protein and turn it into muscle is after your workout.

Google "sarcopenia"

AntoniaZ wrote: »

corrine9720 wrote: »

Hi there I am just starting out and want to use my treadmill a few times a day is it more beneficial to eat before or after breakfast

I have lost 126 pounds since June 2021.

I seriously weight train in the a.m. three times a week. Before I do, I have two giant cups of strong coffee (half decaf) with 1/4 cup of soy milk in each. I can then power through. I eat a large hi-protein and fibre breakfast afterward.

I do an indoor cycle 3-5 times a week, usually in the evening. I eat a large high-protein and fibre dinner afterward.

The best time to synthesize protein and turn it into muscle is after your workout.

Google "sarcopenia"

Sure, sarcopenia** is a scary thing. It can happen if someone doesn't eat get decent nutrition, doesn't stay active. It's more common in the elderly, partly because of declining activity and nutrition also being common, but perhaps with contributing factors that protein metabolism and muscle protein synthesis can become less efficient with age.

If you (the general reader here) get enough protein throughout your day, and are otherwise healthy, then normal strength training workouts, and normal exercise classes (even intense ones), are not going to bring on sarcopenia. This is true even if you choose to exercise fasted, or choose not to eat after a late-evening workout.

Even if you don't eat substantial amounts of protein, but just the usual lowball-ish USDA/WHO recommended minimum amounts, you're not going to doom yourself to early-onset sarcopenia if you don't eat protein right after your exercise.

Muscle protein synthesis may be enhanced if you do get protein soon after workouts, but *sarcopenia* if you don't? Absent some other major medical problem, not a rational worry.

Get well rounded nutrition, including adequate protein. Get some exercise, because non-use of muscle is one of the significant factors in sarcopenia. Meal/nutrient timing around exercise isn't materially increasing (or decreasing) your risk.

** See, for example, "Clinical definition of sarcopenia", Clin Cases Miner Bone Metab. 2014 Sep-Dec; 11(3): 177–180.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4269139/

Sarcopenia is a condition characterized by loss of skeletal muscle mass and function.
. . .
There is an important correlation between inactivity and losses of muscle mass and strength, this suggests that physical activity should be a protective factor for the prevention but also the management of sarcopenia.
. . .
Although sarcopenia is primarily a disease of the elderly, its development may be associated with conditions that are not exclusively seen in older persons, like disuse, malnutrition and cachexia.

I've clearly picked out a few key relevant quotes above, but not unfairly: There's not the slightest hit of a whiff of the idea that people get sarcopenia by not timing protein/food in a particular way around their workouts, short of actual overall malnutrition.