How to Keep Workouts Strong When Intermittent Fasting
DIETING CAN BECOME complicated, fast. Eat this, don’t eat that, only eat so much of this, and even less of that. When counting, tracking, and planning all start becoming too much, many turn to intermittent fasting as a simpler alternative. While intermittent fasting may help simplify your meal-prep routine, you might find that the practice complicates your workout schedule.
The premise of the intermittent fasting diet is simple: only eat for a small amount of time during the day, and fast the rest. There are several different kinds of intermittent fasting schedules, but the most popular one requires you to fast for 16 hours, then fit your meals into the next eight. Whatever food you eat during that period is up to you, so long as you stick within your eating window (though, filling up those few hours with several cheeseburgers and buckets of fries probably won’t get you very far in the weight loss department).
Food fuels our body for activity, though—and when you take that fuel away for most of the day, your workouts will likely suffer. You may find yourself feeling weak and lethargic in the gym when sticking to a fasting schedule, which is not ideal if you’re trying to build muscle mass and keep yourself in shape. That doesn’t mean you can’t work out when you’re fasting; it’s more a matter of proceeding safely in a way that will still optimize your training. A few small changes in your schedule and practices and you can continue your quest for that dream physique safely.
What Is Intermittent Fasting?
Let’s back up for a moment. First, it's important to understand the intermittent fasting schedule before you consider how to implement the strategy within a workout plan.
The most common type of intermittent fasting is the daily, time-restricting format. Typically, there’s a 16-hour fast, followed by an eight hour eating window. For example, someone could make their eating period between 12 p.m. and 8 p.m., only consuming lunch and dinner.
The time schedule can vary depending on your day. If you’re a person that needs more fuel in the morning, you may run on a 9 a.m. to 5 p.m. schedule instead. The time of day doesn’t really matter, as long as the consumption window sits at eight hours.
If that sounds like something you’re interested in trying, talk to your doctor or a registered dietitian first. Fasting is not appropriate for those that are pregnant, have a history of an eating disorder, or have certain medical conditions—speaking to your doctor will ensure the practice is a healthy choice for you.
What Are the Benefits of Intermittent Fasting?
If you frequently succumb to the temptation of a nighttime walk to the fridge, IF might just be the thing you need to keep your snacking in check and lose that excess weight.
“Intermittent fasting puts a cap on eating and can eliminate or minimize overconsumption at night. This can decrease calorie intake, can help with better sleep as the stomach won't be having a fiesta when it is time for a siesta,” says Leslie Bonci, R.D., M.P.H, sports dietician for the Kansas City Chiefs.
Weight loss isn’t the only benefit to the practice, though. There’s some evidence to suggest that intermittent fasting can reduce the risk of diabetes, lower blood pressure, and help maintain muscle mass.
That said, intermittent fasting is by no means the perfect diet for everyone, or a magic bullet for weight loss. For some, it’s a simple practice that may help eliminate those extra trips to the fridge. But for others, eating in a small window of time is just not sustainable— and the best diet is always one that keeps you consistent.
If fasting is that diet for you, exercise is vital to keep your heart healthy and muscles strong while dieting. Take these tips to schedule your workouts appropriately with your feeding hours.
How to Work Out When You’re Intermittent Fasting
Don’t Try to Build Muscle While Fasting
Whether it’s a 5/2 protocol (eat for five days, fast for two) a 16/8 (fast for 16 hours, eat for eight), or any other version of IF, most people on a fasting diet wind up losing weight. That’s because it’s much harder to overeat if all your daily calories are crammed into an eight-hour window than if you can spread them out over 15 to 16 hours. That’s what makes IF such an effective weight-loss tool: by restricting the time frame in which you can eat, you effectively restrict the number of calories you take in as well.
But if your main goal is maximizing muscle, fasting isn’t a great idea. “Unless you’re a real novice, you can’t build appreciable muscle in a caloric deficit,” says Angelo Poli, ISSA, co-owner of Whole Body Fitness in Chico, CA, creator of the MetPro diet and exercise app. A pound here and there? Maybe. But you won’t build anywhere near as much as you would if you consume a few hundred extra calories above and beyond what your body needs each day. So don’t try. Your primary goal while fasting should losing fat. To build muscle, you need fuel.
You Should Train While Fasting
Even if your main goal is losing fat, you still need to lift, which prevents your body from burning through muscle to fuel your daily activities. You won’t gain much muscle if you’re fasting, but if you lift, you won’t lose it, either. “The same activities that build muscle when you’re fueled help preserve it when you’re in a caloric deficit,” says Poli.
Since you’re only trying to maintain the muscle you have—not pack on additional beef—you can get away with a fairly infrequent lifting schedule—2 to 3 times per week, exercising your whole body each workout (try this routine).
Eat BEFORE You Lift Weights
Lifting weights, sprinting, doing CrossFit WODS, and other high-intensity activities all depend on carbohydrates for fuel, explains Poli. If you perform any of these activities during (or worse, at the end of) your fast, your performance will suffer. Instead of getting stronger and faster, you may well get weaker and slower.
What to do? “If you’re a big guy with a lot of weight to lose, no big deal,” says Poli. “Go ahead and lift on an empty stomach. You might lose a little bit of muscle, but you’ll burn fat, too—and that’s your main goal.”
If you’re a slimmer guy worried about your muscle definition, no need to worry— we have a solution for you too.
Sandwich Your Workout
It’s vital that you eat before you workout so that you can get the most out of your lift, but depending on your build, it might be good to ensure a little something afterwards. “Eliminating the post-workout refueling may delay recovery as well as muscle protein and muscle glycogen resynthesis,” says Bonci.
So, if you’re on the slimmer side and are worried about losing some of your muscle definition, it’s probably better to schedule your lifting workouts during your feeding window. So if you eat from noon to 8 p.m. each day, try to hit the gym around 5, then go home and eat a high-protein meal to ensure adequate recovery from your workout.
Bonci suggests sandwiching your workout into your meals if you’re limiting calories. Meaning, eat one third of your meal before the gym, and the other two thirds of the meal afterwards. That way, you get some in before to power the workout, and the rest after to recover. “Ideally, food and fluid would parenthesize the workout,” she says.
Overall, it’s best to do your best to fit your workout into your eating period so that you can have something before and after. If your schedule just doesn’t allow for it, it might be time to adjust the structure of your eating period— either by extending it, or changing the start and end times. “The window of eating may need to be longer to accommodate physical activity,” says Bonci.
Fast Before Cardio
While fasted lifting is a big fat mistake, fasted cardio is fine—but know that fat burning and fat loss are not the same. This means your body is burning fat as an energy source—and, without a calorie deficit, those stores will be replenished. Fasted cardio is safer than fasted weight training, though—since your body uses fat stores for slow, steady-state cardio activities. For best results, schedule those lifting sessions during or after your feeding windows, and schedule cardio before them.
The Bottom Line
The key to exercising safety while using IF is to listen to your body. If you’re starting to feel light-headed after hopping onto the treadmill for some fasted cardio, be smart about the situation and stop and grab some food and water until you feel okay to start again. Carry a snack in your gym bag, for example, just in case.
To ensure you’re following a program that fits best to your body, speak with your doctor before starting up any new diet or workout program. They will be able to help you determine what will be safe and effective for you.
You Might Also Like
