A top performance scientist says the popular “30 grams of protein per meal” rule is a myth, and the real number people need changes a lot depending on whether they are gaining or losing weight.
Quick Take
- Dr. Andy Galpin says about 1.6 grams of protein per kilogram of body weight each day is the sweet spot for building muscle while eating enough calories.
- A major scientific review backs that number, showing extra protein stops helping much past roughly that level.
- Galpin says people trying to keep or build muscle while cutting calories may need closer to 3 grams per kilogram.
- He calls the idea that bodies can only use 30 grams of protein per meal a myth, not a hard rule.
- Strength training, not protein alone, remains the main driver of muscle growth, according to Galpin.
Scientist Sets A Clear Protein Target
Dr. Andy Galpin, a performance scientist who studies muscle and exercise, laid out a simple number for people trying to build muscle. He said the rough target is about 1.6 grams of protein per kilogram of body weight each day. That advice applies to people eating enough calories to grow, not people cutting weight.
This is not just one expert’s guess. A large 2018 review looked at 49 studies and nearly 1,900 people. It found that eating more protein than about 1.6 grams per kilogram per day did not add extra muscle gains. The study’s upper safety range reached about 2.2 grams per kilogram before results flattened out completely.
The Number Changes When Cutting Calories
Galpin pointed out that his 1.6 gram target only works when someone eats enough to grow or maintain muscle. During a calorie deficit, meant to lose fat, he said protein needs can jump to around 3 grams per kilogram to protect and still build muscle. Other nutrition research backs the idea that cutting calories raises protein needs, since the body works harder to hold onto muscle when fuel is short.
That higher deficit number comes from Galpin’s own expert read of the research, not a single named study with an exact confidence range like the 1.6 gram figure. Still, broader nutrition science agrees that protein needs go up substantially during calorie restriction paired with resistance training.
Debunking The 30-Gram Meal Myth
Many gym-goers believe the body can only absorb and use about 30 grams of protein in one sitting. Galpin called that claim a myth. Research instead points to eating around 0.4 grams per kilogram of body weight per meal, spread across at least four meals a day, as a better way to hit the daily 1.6 gram target.
That means a person does not need to obsess over hitting an exact number at every meal. Spreading protein out across the day, rather than chasing a fixed ceiling, appears to matter more for building muscle over time, based on the available research.
Training Still Comes First
Galpin stressed that strength training matters more than protein intake alone. Eating the right amount of protein supports muscle growth, but it cannot replace the physical stress that lifting weights places on muscles to force them to adapt and grow. The 2018 review that backs his 1.6 gram number also studied protein only alongside resistance exercise, not protein by itself.
Why The Science Gets Confusing
Nutrition advice often gets boiled down into single headline numbers, which can make expert guidance sound contradictory even when it is not. Galpin’s numbers range from 1.6 grams to roughly 2.2 grams, up to 3 grams per kilogram, depending on whether someone is gaining or losing weight. Each number comes with its own condition attached, and skipping that context is where confusion usually starts.
Supplement companies and coaching programs often profit from convincing people they need more protein than science supports. That commercial interest can color how people hear even careful, conditional advice from a credentialed scientist. Readers weighing protein advice should pay attention to whether the source separates muscle-building phases from fat-loss phases, since the two call for very different amounts.
For most people trying to build muscle while eating enough to grow, roughly 1.6 grams of protein per kilogram of body weight spread across several meals, combined with consistent strength training, lines up with the strongest available evidence.
Sources:
youtube.com, pmc.ncbi.nlm.nih.gov, thefabulous.co, experts.mcmaster.ca, journals.humankinetics.com
