I’ve been doing StrongLifts for about 6 months now, and have always felt better working out when I don’t have anything in my stomach.
I’m doing a 30-day program with my gym, and everyone who signed up gets a free body composition measurement before and after the program. We have to come to the first measurement fasted, so I asked if it was possible to work out before the measurement since it’s on one of my usual lifting days. The gym owner responded by telling me it’s “possible as long as you don’t eat, however I don’t recommend working out on an empty stomach.”
Is this legit advice? I have searched high and low on the internet for the answer to this damn question, and it seems to always be “whatever feels best for you.” Is this the case? Is there science or fact to back up one over the other? There’s a chance I’ve even asked you for help before. Help!?
There probably isn’t an easy answer out there because there isn’t an easy answer that exists, but what you’ve found so far is basically right: If you feel terrible eating before working out, then it doesn’t make sense for you to do so. I’ve personally found that my own results can vary workout to workout: I can do squats just fine having eaten within the last hour or two, but if I do the same and try to do a deadlift, I get weird and deeply uncomfortable pressure in my stomach when I try to brace my core. So, yeah, count this as another vote for “whatever feels best for you.”
But about the science of it all: The idea of working out “fasted” has become very trendy in our culture, because people think that doing so means your body will “pull energy directly from its fat stores,” or some such. There’s some truth to the fat-stores thing—when you work out, your body first uses glycogen (from carbs) for energy, but if you’re low on glycogen (because, say, you’re working out first thing in the morning and haven’t eaten since dinner last night), your body will turn to fat for fuel instead. So in theory it makes sense, but in practice it can get a bit more complicated than that—the science is mixed, and the type of workout you do matters, and so on. And then there’s the issue that working out in a fasted state might mean that you aren’t as productive or efficient as you could be, which might get in the way of your progress (more on this in a bit). All of that is to say that, for body-fat composition goals, your pre-workout eating habits may not actually be as important of a factor as you think, science aside. Might they matter for, say, a bodybuilder in their final weeks of competition prep? Yes, possibly. For a more typical or casual exerciser? Probably not so much.
However, the body-fat composition stuff is a separate issue from 1) comfort and 2) fueling your workouts in general. For a lot of people, having some fuel in the tank before exercising can mean the difference between a productive workout and a lousy one (or even passing out during a deadlift, which, yes, actually happens). That doesn’t mean you need to eat a full meal before working out (which, honestly, you probably wouldn’t want to work out after a full meal anyway), but sometimes simple snacks can make a huge difference in performance. That being said, the most important thing with eating and working out is making sure you are fueled generally; if you undereat for a week, but make sure to have a snack before working out, that extra snack probably isn’t going to do much for you. But if you’ve been eating well leading up the workout—meaning eating enough food, and also getting enough in the way of nutrition—then a snack before a workout could make a difference.
Some people like a snack of roughly 200 calories or so that is mostly quick-fueling carbs; I eat candy even. I bought a five-pound bag of sour gummy worms about a year ago that I’m still working my way through. 200 calories is not much, and definitely not the difference between feeling full or not full (at least not in my experience), so even if working out on a full meal bothers you, a small, easily digested snack might not.
For longer workouts, some people even like “intra-workout” snacks or drinks that will boost their energy a bit and help them rehydrate and replenish their electrolytes (yes, the snack can even be a drink!). This might be a familiar concept if you’ve say, ever run a long race. We know enough now about the benefits of periodically refueling with some carbs that you’d be hard-pressed to find a half-marathon or longer race without sports-drink or even energy-gel stations to keep runners going. I learned this the hard way the first time I ever ran nine miles (as part of a reasonably paced training program) on nothing but a few sips of water; I nearly blacked out in a Whole Foods. The same principle applies to lifting; you’re doing something quite taxing, and it might help you to finish a workout strong if you goose your energy and hydration levels a bit with a snack during.
All of this is probably why your gym owner doesn’t advocate working out on an empty stomach, particularly if you haven’t fueled up properly during the day; your body is, in the end, a pretty simple set of mechanisms, and it needs energy to do things. There is also just the matter of timing: if you go into the gym having not eaten in 3 to 4 hours, spend an hour in there, by the time you leave and reach a source of food you probably won’t have eaten in close to 6 hours, which… it kinda sucks to not eat for that long on purpose, if you’re not sleeping! It would be nice to have a little snack in there.
Fortunately, SELF has an absolute embarrassment of snacking options we can tell you about. In my experience, most lifters would agree that your snack should be mostly simple carbs to top off your glycogen, with a smidge of protein or fat (more like a banana or apple with a little peanut butter, less like a small handful of almonds). And here’s what a registered dietitian recommends, if you’re curious. But if you’re mostly just trying to stay not-starving between meals, whatever you like works. Maybe the most important thing is to experiment with what you like and what feels best. If you think you feel OK without snacks, you might be surprised to find you feel even better with them. Or maybe you’ll hate them! No one, including your gym owner, can tell you for certain what will make you feel best. But if you’re looking for levers to pull to optimize your time in the gym, not just for effort but for how you feel, snacks might actually be what you’re looking for.
Strength is for everyone, but it’s especially for women. Ask a Swole Woman is a column for people who are tired of trying to always be less, eat less, do less, and make it look perfect and effort-free. Have a question for me about strength training or anything related? If you’re ready to give your body what it needs, to test your grit, and become more than you ever have been, email AASW@self.com.
Casey Johnston is the editor of the Future section at The Outline and a competitive powerlifter with a degree in applied physics. She writes the column Ask a Swole Woman for SELF. You can find her on Twitter: @caseyjohnston.