What’s more, overprioritizing protein shakes, in turn, could affect the state of your stomach, including how easily and frequently you poop. For example, lots of them lack fiber, so stacking your diet with these beverages could increase your risk of constipation, setting you up for a tough few bathroom trips. Or it could push you over to the other extreme. Some shakes contain ingredients (like artificial sweeteners or sugar alcohols) that can cause digestive issues—so the more you drink, the more likely you are to experience side effects like bloating, gas, and diarrhea if you have a sensitive stomach.
Of course, that one-per-day recommendation comes with some caveats, since the amount of protein people need can differ across the board for a wide range of reasons. For example, folks who have chronic kidney disease may be told to reduce their daily protein intake because their kidneys have trouble filtering out the resulting waste, Jason Machowsky, MS, RD, a sports dietitian and registered clinical exercise physiologist, tells SELF—so even one shake could theoretically pile on too much protein for their organs to comfortably handle if they’ve already met their daily limit. On the other end of the spectrum, very physically active people, like athletes, likely need extra protein to maximize recovery and muscle growth. Besides, the actual amount you’re taking in differs between shakes (though you typically want to shoot for 10 to 20 grams of protein if you’re drinking one as a snack between meals rather than a meal substitute), so multiple drinks at the lower end of that range could deliver the same protein content as one at the higher end. In other words, “it’s hard to generalize,” Isaacs says.
For that reason, don’t feel completely tied down when it comes to the earlier gen-pop guidance: For those who have higher protein needs—say, you’ve got lofty fitness goals that have you working out hard and often—it may well be just fine to drink more than one shake per day, according to Isaacs. “In situations where time is limited, appetite is reduced, or there’s a need for quick recovery after a workout before a meal, protein shakes can be a convenient option,” she says.
The bottom line: Whether you’re sticking to one protein shake a day or you’re edging above it thanks to higher dietary protein requirements, you should still consider what you’re drinking a complement to your meals rather than something to replace them entirely, Isaacs says. Otherwise, you may be “missing out on important nutrients,” she adds. Sure, there may be special cases “where someone would need more or less,” Machowsky says, but if that’s the situation, you should consult a professional—say, a registered dietitian nutritionist—for medical advice. And if you’d prefer to get your protein from solids rather than liquids but want to nibble on something a little less dull than a protein bar, check out this list of 22 high-protein snack ideas.
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