Interest in protein has surged far beyond the traditional fitness market, with rising demand for protein supplements making it hard for manufacturers to keep up.
Creatine, too, is having a moment. Three decades after it first emerged as a safe and effective ergogenic supplement for strength and power athletes, research now suggests that it may offer cognitive benefits as well.
Protein and creatine supplements are suddenly relevant to patients who barely knew they existed just a few years ago. That means every patient demographic, from teens to seniors, will expect you to answer their supplement-related questions.
Are they safe? Do they work? What types are best? How much should they consume? What if they’re taking a GLP-1 for weight loss?
Before we answer them, it’s important to put both supplements in the proper context.
How Protein, Creatine Work Together, How Different
“I frame protein supplements mostly as convenience foods,” said Andrew J. Mock, MD, an obesity researcher and assistant professor of preventive medicine at Loma Linda University School of Medicine in Loma Linda, California, as well as a family practice physician in Southern California. They give us an easy way to facilitate muscle recovery and growth post-workout and help preserve lean body tissue in situations where we may not get enough protein from our meals.
“Creatine is different,” Mock said.
Unlike protein, which is a key structural component of everything from muscles to hormones, creatine is an energy substrate. We use it to fuel quick bursts of activity requiring strength and power, such as sprints and heavy lifts.
Your body can synthesize about 1 g/d or 2 g/d from food sources such as meat and fish, which gives your muscles about 60%-80% of the creatine they can hold.
“It’s actually difficult for most people to consistently consume enough through diet alone to fully saturate muscle creatine stores,” Mock added. “That’s part of why supplementation tends to be more practical and reliable.”
Which leads us to the first question doctors often hear about protein and creatine supplements.
Safe?
Stuart Phillips, PhD, has studied protein and resistance training for more than 30 years. When he talks to doctors, he still hears some version of this question: “Isn’t more protein bad for the kidneys?”
“The kidney worry is the one that won’t die,” said Phillips, a professor of kinesiology at McMaster University in Hamilton, Ontario, Canada, and co-host of the Exercise Science podcast. “And it’s the one that most often leads to bad advice being passed along to patients who would benefit from eating more protein, not less.”
The idea that a higher-protein diet would damage the kidneys of healthy individuals comes from a 1982 paper in The New England Journal of Medicine. It’s been repeatedly debunked.
The same question often comes up with creatine, Mock said, even though “it’s one of the most well-studied sports nutrition supplements we have, with a very favorable safety and efficacy profile.”
Studies have consistently shown that it leads to measurable and often meaningful improvements in strength, power, training capacity, and muscle mass.
“There’s also growing interest in creatine for healthy aging and potentially cognitive or neuroprotective applications,” Mock added, “though the evidence is still evolving.”
How Much Needed?
Phillips recommends 1.2-1.6 g of protein per kilogram of body weight per day, which is also what the US government recommends in its Dietary Guidelines for Americans.
“That’s a reasonable target for most adults who care about body composition or healthy aging, with the higher end of that range — and sometimes beyond — for older adults, for people losing weight, and for those doing serious resistance training,” he explained.
For an adult who weighs 180 lb/82 kg, that’s roughly 100-130 g/d. For someone who weighs 145 lb/66 kg, that’s 80-105 g.
It doesn’t matter if you get all of it from whole foods or if you get some from a supplement. “It’s food, not a drug,” Phillips said.
For creatine, “3-5 g/d is effective for almost everyone,” he said. (You’d have to consume more than a kilogram of meat to get 5 g of creatine from diet alone.)
With GLP-1 medications?
Early reports suggested that weight loss with GLP-1 medications led to a disproportionate reduction in fat-free mass.
More recent estimates are much lower, leading to a huge range of potential outcomes — from 12% to 40% of total weight loss deriving from lean tissue, including muscle.
So it’s understandable that patients taking GLP-1s want to preserve as much muscle as possible.
“We get a lot of questions about protein and creatine and basically what’s going to optimize their journey while they’re on a GLP-1 medicine,” said Spencer Nadolsky, DO, an obesity and lipid specialist and founder of Vineyard, a comprehensive telemedicine group.
Nadolsky said the most common question he hears is how much protein those patients should get in a day. His answer: a relatively low 1-1.2 g per kilogram of body weight per day.
“The medicines reduce your appetite quite a bit,” he said. Even with a daily protein shake, it can be difficult for a heavier individual to consume much more than that.
But recommending a bit less protein doesn’t mean Nadolsky puts any less emphasis on preserving muscle.
For that goal, he said, “protein is a distant second to resistance training.”
What Type Protein, Creatine to Use?
For creatine, that’s an easy one: “Creatine monohydrate has one of the strongest safety and evidence profiles in all of sports nutrition and exercise science,” Mock said. “It has been extensively studied across a wide range of populations.”
Look for a single-ingredient supplement from an established company that uses third-party testing, he suggested, while avoiding products that include creatine as part of a proprietary blend.
Selecting a protein supplement is more complicated. “I tell patients the ‘best’ one is usually the one they tolerate, can consistently use, and that fits their dietary pattern and goals,” Mock said.
If your diet is omnivorous, you’re in luck: Whey protein isolate is rich in leucine (the most important amino acid for muscle protein synthesis), is highly digestible (most of the lactose has been filtered out), and has been used extensively in high-quality research.
If your diet is vegan, you’re still in luck because plant-based protein blends compare favorably with dairy proteins. In a 2024 study, Phillips and his co-authors found that a plant-based supplement with added leucine stimulated muscle protein synthesis to a similar level as whey isolate.
How Much Protein in a Single Meal?
This is really two questions:
- How much protein do I need to maximally stimulate protein synthesis?
- Is it true that anything beyond that amount is a waste?
We’ll start with the second question because Nadolsky hears it from patients way more often than he’d like to.
“I tell them, no, it’s not a waste,” he said. Even if the patient has fully engaged protein synthesis, there’s a lot more going on. The total amount of daily protein in your diet and the quality of that protein matter more than how much you eat at any particular meal.
For the first question, Phillips has three answers:
- In younger adults, about 0.25 g of high-quality protein per kilogram of body weight per meal should adequately stimulate protein synthesis. That assumes the protein contains 2-3 g of leucine.
- Older adults who have some resistance to leucine should aim for 0.4 g per kilogram per meal.
- Maximum protein stimulation should occur with roughly 0.4-0.55 g per kilogram.
Put simply, 20 g of protein per meal should get the party started for a younger adult, 30 g should work for an older adult, and 40 g should maximally engage protein synthesis for almost anyone.
But again, higher amounts of protein at one meal aren’t “wasted.”
In fact, a 2023 study found that 100 g of protein stimulated more protein synthesis over the next 12 hours than 25 g.
Nobody is suggesting you should consume 100 g of protein in any meal. Even if we thought it was a good idea, few of us could choke down 1.2 pounds of beef, two large chicken breasts, or 16 eggs at one sitting.
The point to make to your patients is this: Consume the nutrients your body needs, and your body will figure out what to do with them.
Supplements Even If I Don’t Work Out?
“In some cases, yes,” Phillips said.
“For an older adult who can’t comfortably hit their target from food, or someone with a small appetite, or a busy person who skips breakfast, a scoop of whey or a similar product is a convenient, evidence-based tool.”
That’s especially relevant to patients of any age who’re taking a GLP-1 medication and have the double challenge of suppressed appetite and potentially significant loss of muscle and other lean tissues.
The benefits of creatine, as noted, primarily relate to performance. If a younger patient isn’t actively training, there isn’t really any performance to enhance.
But if an older patient is interested in creatine for the potential cognitive benefits, there’s no reason to discourage them. “It’s low risk, inexpensive, and potentially helpful,” Mock said.
Still, for most patients, protein and creatine supplements have few benefits outside the context of strength training.
Phillips offered an analogy:
“Resistance exercise bakes the cake, protein adds the (thin) layer of icing, and creatine is the sprinkles,” he said. “In order of the benefits they offer, that’s how they stack up: cake before icing before sprinkles.”
Those cited in this article had no relevant disclosures. Disclosure information for study authors is available in the original study publications.
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