It’s not enough just to make it through your workout in one sweaty piece. You also have to save enough time to fuel back up properly post-workout with enough protein, complex carbs, and other vitamin and minerals — such as potassium and magnesium — in order to restore your electrolyte balance and speed up muscle recovery.
When you work out, you’re using and breaking down muscle. And while your muscles will get stronger over time from the training — especially if you’re doing weight training — you are taxing your muscles throughout the workout, so they’ll need some rest and repair shortly afterwards.
“If you’re just recreationally active, you technically have two hours to eat protein and carbs after a workout so that you have the opportunity to effectively repair, maintain, and/or grow muscle,” says Kelly Jones, MS, RD, CSSD, LDN.
This recommendation might be ideal for someone who is doing a lower-intensity workout or is just active throughout the day through recreational sports, cycling, walking, biking, or roller-skating, for example.
Yet, this two-hour time frame is also only acceptable if you have eaten adequately before your training session, such as consuming a solid breakfast before a morning workout.
Related: Master the Post-Race Refueling Window
“It doesn’t account for replenishing nutrient stores for your next workout, or for hydration nutrients,” she says.
For the most part — and for athletes training at a more advanced level — those challenging high-intensity workouts will require you to eat within the same hour to make sure that you’re giving muscles some immediate protein, which is essential for muscle repair. Here’s what happens if you wait too long.
Your Muscles Don’t Get Enough Protein to Recover Well
How much protein do you need?
“Depending on your goals, you’ll want to consume somewhere between 0.25 and 0.4 grams per kilogram of body weight — around 0.11 to 0.18 grams per pound — of protein after exercising and 1 to 1.5 grams per kilogram — 0.45 to 0.7 grams per pound — of carbohydrate,” Jones says.
This is the right balance for high-fiber and complex carbs, which provide immediate and sustainable energy for a quick boost as well as keeping your body energized for the next couple of hours. Protein is also targeting the muscles directly, aiding in repair, strengthening, and defining of those worked muscle groups, so you’ll steadily improve performance over time (and see those visual results in the mirror, too).
You Can’t Replenish Depleted Electrolyte Stores
“If you have a high sweat rate, exercise at a moderate-to-high intensity for longer than an hour, or exercise in a hot environment, a source of sodium is important then, too, in order to maintain hydration,” Jones adds.
Sodium will help balance your electrolyte levels, as you likely depleted most of your balance through that heavy perspiration. You’ll need sodium and other electrolytes — like magnesium and potassium — in your post-workout fuel meal.
Try these easy options: a banana and leafy green smoothie with nut butter, or a bowl of cottage cheese with fresh berries and a serving of nuts and seeds all atop a slice of whole grain toast.
Think of Your Last Meal — How Much Longer Can You Go?
If you don’t eat a healthy and balanced snack that hits all the macronutrient marks — protein, good fats, and fiber — as well as offers electrolyte sources, you risk prolonging muscle damage and hindering repair. And a lack of nutrient supply and rest can interfere with your fitness gains big picture, since you’re not letting the muscles heal and grow stronger and leaner.
Fuel is needed to promote enhanced muscle building, and if you’re not eating often enough or eating in that hour window after working out, your body may start to use muscle as fuel for energy instead. This leads to fat storage, muscle loss, and an inability to build stronger, more defined muscle.
You’re Not Replenishing Glycogen Stores
“In addition to optimizing muscle repair and replenishing muscle energy (glycogen) stores, eating after a workout helps maintain normal appetite signals throughout the day,” Jones says.
So, you’re better able to control your appetite, cravings, and mindless snacking.
“Post-exercise appetite suppression is common, so even if you aren’t hungry, your body may still actually need the energy and nutrients," she warns. “If you don’t eat, you may become excessively hungry later, leading to impulsive decisions about what to eat and even binge-like tendencies."
Regardless of training intensity and as backed by research, both men and women often experience appetite suppression post workout, which makes it hard to remember to eat if your stomach isn’t growling. And if you think that you should use appetite suppression to your advantage as a way to skip the calories in the day, be warned. It will ultimately set you back, causing loss of hard-earned muscle.
You’re Breaking Down Your Hard-Earned Muscle
If you’re not fueling your muscles properly after a workout, you could lose all the muscle-building benefits that you were achieving.
“Your body is using energy constantly throughout the day, even when you aren’t exercising," Jones says. "After an intense training session, energy metabolism may be even higher at the same time that your muscle cells are most sensitive to the ability to take in energy and protein for repair.”
Without food, you might be breaking down not only fat, but also muscle protein that provides energy to maintain normal bodily functions. Unfortunately, a lack of sustenance can impair progress with your training program and could actually lead to increased risk of muscle injury too.
It Can Affect Your Entire Body
In addition to poor recovery and appetite cues, lack of energy intake may impair your ability to pay attention or be productive at work or during other tasks.
“Lack of energy intake can mean lower blood sugar levels, making your body think that you don’t have enough energy to stay sharp mentally," Jones says. "In some people this can even increase the release of stress hormones like cortisol, and impact your mood."