If your belly is making sounds like a dial-up modem from the ’90s, you might feel the need to chow down rather than work out. (For those who are confused: We didn’t always have magic rectangles in our pockets that could tell us everything about ourselves or the world in a matter of seconds.)
However, it may be better than you think to start pumping reps before filling your face. In this article, we give you the full picture of when to eat and when to lift.
Editor’s note: Before changing your diet in any major way, please speak with a health professional to make sure it’s the best decision for you.
When humans were hunter-gatherers, unable to order food that would arrive at their door in 10 minutes via a scooter, they didn’t get to eat until they’d finished being active enough to kill a mammoth or climb a tree to get at those sweet, sweet berries.
But it isn’t as easy as “Well, it worked for my great-great-great-great-great-great-great-great-great-great grandma, so I’ll be good to go.”
Different people work out best under different circumstances, and deciding whether someone should eat before training can be like telling them what time of day to work out or which diet they should follow — it largely depends on what works best for you.
(Here’s our guide to why eating right and working out are the bee’s biceps.)
It’s time to dismantle some old myths. Contrary to popular belief, research suggests that eating many small meals throughout the day won’t speed up your metabolism, skipping a meal won’t make you fat, and exercising on an empty stomach will not nullify a workout. Who knew?
In fact, skipping a meal or two, also known as intermittent fasting (IF), can downright boost your whole swag.
If the fact that Huge Jacked-man practiced IF to gain muscle for his latest Wolverine movie weren’t convincing enough, consider this: An empty stomach triggers a cascade of hormonal changes throughout your body that are surprisingly spot-on for both building muscle and burning fat. Mind-read that, Professor X.
The fasted state produces two significant effects:
1. Winsulin: Improved insulin sensitivity
To put it very simply: Your body releases a hormone called insulin when you eat. This helps you absorb the nutrients from food.
The hormone then takes sugars from your bloodstream and directs them to your liver, muscles, and fat cells, where they enter storage — kind of like a U-haul guy flinging your belongings into a dank, moldy container while you sofa-surf.
The trouble is that eating too much and too often can make you more resistant to insulin’s effects. Poor insulin sensitivity ups your risk of heart disease and reduces how offended insulin will get if you challenge it to a rap battle.
Insulin resistance is also bad news for the onset of type 2 diabetes. This can cause regular spikes in blood sugar (and not cute hedgehog ones). Your cells react less to insulin, leaving too much sugar to circulate in your bloodstream.
In further bad news (it’s 2020 — there’s enough for everybody), insulin resistance can also increase your risk for cancers of the colon and rectum.
Eating less frequently is one way to help check your insulin sensitivity before it wrecks itself. If you eat less often, your body releases insulin less often, so you become more sensitive to it (or remain that way). IF can also contribute to weight loss.
2. Growth hormone: The magic beanstalk
The second reason a good old-fashioned fast might promote muscle gain and fat loss comes down to growth hormone (GH).
This is a Swiss army knife of a hormone that helps your body make new muscle tissue and burn fat,
Along with regular weight training, getting enough sleep, or being a Pokémon on the cusp of evolving, fasting is one of the best ways to increase your body’s GH level.
A 2011 study showed that 24 hours without food increased GH production by 2,000 percent in men and by 1,300 percent in women.
The effect ends when the fast does, which is another reason to fast regularly and keep muscle-friendly hormones at their peak. But you need adequate calories and protein to build muscle, so refueling after a fast is critical.
While interesting, this data still doesn’t tell us what happens to the body during fasted exercise.
The news on the potential benefits of fasted exercise ranges from ambiguous to not-so-great.
One study followed a group that stuck to an IF diet through 8 weeks of resistance training and a group that didn’t. The researchers found that, while the IF group didn’t have improved muscle mass compared to the other group, IF also didn’t make exercise any less effective.
But the study didn’t specifically look at exercise buffs pumping iron in a fasted state. Back to square one, then?
Not exactly. One earlier study suggested that the cells of a group who fasted before exercise processed protein and carbs more efficiently than those of a group who had a carby breakfast before starting their workout.
An even earlier study, going back to the age of keytars and fascinating mullets, suggested that avoiding food before exercise helps the body use more fat without messing with the balance of its stored sugars. The study didn’t explore the effects of keytars and mullets on glycogen homeostasis.
A 2011 study on fasted training found that fasted exercise might affect how quickly the body uses proteins and converts them into muscle.
The same way that realizing who your Tinder date actually is after 5 minutes can increase the speed at which you bolt out the door, fasted training might help your body get the right outcome efficiently. And it won’t text you afterward threatening to burn your underwear.
However, as with problematic Tinder experiences, there’s no guarantee you’d get the same success next time. These studies are small and a little outdated, so we can’t necessarily take them at face value. The issue remains controversial, like asking your pals whether the dress was black and blue or white and gold.
Fasted and fed exercise regimens can lead to different body responses when burning fat and carbs.
But fasted training might not be as great for long-term fat loss as you think.
There may be potential benefits when endurance athletes fast before doing their thing, since fasted workouts might improve muscle glycogen storage efficiency (yeah, we know some long words — eat it, Godzilla challenge).
There’s a snag, however: The American College of Sports Medicine takes the position that loading up on pre-workout carbs can also boost performance. Hmm.
The gains in people who do eat before exercise stand as pretty good evidence that pumping iron after eating can work. Heck, there are even studies showing that eating before exercise can lead to a lower calorie intake throughout the day.
The evidence that fasted workouts, even if occasional, might reap benefits in some people is limited. But if you find that it feels better and gets great results, then fasted exercise isn’t going to do any damage or undo the gains of a previous fed workout.
Essentially, as long as you’re eating the right stuff and moving in a way that has an impact, your muscles will love you for it.
We know what you’re thinking: “I can’t handle intense exercise without food in my belly! Give me my protein snacks! I wonder who’s leaving the show on ‘RuPaul’s Drag Race’ tonight. Wait, did I leave the oven on?”
OK, so we didn’t need that much information. But firstly, give yourself a little credit! With the right mindset, you’re capable of more than you think. Secondly, there are several tips you can follow to help you with this new approach to eating:
You can consume more than just water during fasting periods
Feel free to quell cravings and get an energy boost with black coffee, plain tea, caffeine pills, creatine, or just good old-fashioned H2O.
Break your fast whenever you’d like
Some people like to eat their first meal right after exercising, since the fast improves the absorption of the post-workout meal. But it’s no big deal if the fast lasts a while longer.
Even if you exercise in the morning and don’t eat until the evening, the wave of GH you’ll be riding all day may help prevent muscle loss.
Eat as many meals as you want
Note: We didn’t say as many calories as you want — but nice try.
It’s not necessary to eat many meals throughout the day. Despite some long-held myths that your body can absorb only a certain amount of protein at a time, we’re completely capable of digesting the day’s intake in one big meal (of course, this doesn’t mean that you need to!).
Studies have shown that doing so results in no muscle loss.
Good things are worth waiting for, and a lot of protein just takes longer for a person to digest and use. But, indeed, digest and use it we do.
Even after taking in a regular-size meal, your body is still releasing amino acids, the Lego bricks of proteins, into your bloodstream. Your trusty muscles are sucking them right up about 5 hours after eating.
However, not all proteins are created equal, and options like whey protein absorb into the muscles pretty rapidly.
So play around with the eating times and styles that work best for you. We’re not the boss of you, and in this case, neither is your boss. Your body will tell you how it feels. You’d better listen, or else a one-star Yelp review is on its way.
The short of it: Metabolism and the digestive system are simply not the tantrum-prone toddlers that some might have us believe. You’ve got plenty of wiggle room when it comes to deciding on a pre-squat nosh.
Eating is maybe the most ingrained habit we have, and humans love a habit — just ask your nearest nun.
Disrupting eating routines by skipping a meal or two can be a Herculean task for some people, particularly those who have lived with disordered eating or currently do.
It’s true that IF takes some getting used to. Your body learns not to expect regular care packages of food, and your mind also needs to adjust. That discomfort usually passes, but if IF just isn’t for you, there’s no need to keep it up.
Still, don’t be afraid to try it. IF is just one approach to health and fitness, and it’s certainly not the only one that can get results. (You might also consider the cutting diet, a different approach to building muscle through food.)
In general, there’s no need to eat before exercise. If you feel better when you do, then by all means, keep it up. But if choking down a pre-workout banana or bowl of oatmeal is a chore you do only because it’s supposed to help you avoid muscle loss/fat gain/growing antlers, then it’s time to relax.
You’re completely free to eat whenever feels best in relation to exercise. It’s got your back — and all the other bits as well.