The single most important fact about aging muscle.
If you remember only one piece of information from this entire campaign, make it this one.
When a 25-year-old eats 20 grams of protein, their muscles respond by activating a process called muscle protein synthesis. The signal is loud and clear: build, repair, maintain. When a 65-year-old eats the same 20 grams of protein, the muscles barely twitch. The signal arrives. It doesn’t get amplified the same way.
This is called anabolic resistance, and it is one of the most replicated findings in muscle biology over the last twenty years. Researchers like Stuart Phillips at McMaster, Elena Volpi at Texas, Luc van Loon in the Netherlands, and Doug Paddon-Jones have all shown the same thing from different angles. As we age, the same dose of protein that built muscle in our 30s no longer moves the needle the same way.
The fix is twofold, and it’s genuinely simple. Which is why I like it!
First, older adults need a higher protein dose per meal. The research consistently lands around 30 to 40 grams of high-quality protein at each meal, versus 20 to 30 grams for younger adults. Below the threshold, muscle protein synthesis barely activates. Above it, the build signal fires.
Second, older adults need more of a specific amino acid called leucine per meal. Leucine is the master switch that tells muscle protein synthesis to turn on. About 2 to 2.5 grams of leucine per meal works for younger adults. For older adults, it’s closer to 3 grams per meal.
The simplest way to hit the leucine threshold is with high-quality animal proteins: whey, eggs, dairy, fish, lean meat. Plant proteins work too, but you need more total grams to reach the threshold.
Here’s the part that explains why so many older adults silently lose muscle without realizing it: national survey data shows that most older adults only hit the leucine threshold at one meal a day — dinner. That will not work if you want to stop anabolic resistance!
Here is what members tell me so often over the last decades. Breakfast is typically a piece of toast or a bagel, maybe some cream cheese. Maybe cereal or Instant Oatmeal and they make sure to tell me it is gluten free! And coffee. Lunch is often a salad sometimes but usually a sandwich. Both meals come in well under the threshold. So muscle protein synthesis fires only once a day. The rest of the day, the body is in a slow drain.
Multiply that pattern by ten or more years and you’ve explained a huge fraction of age-related muscle loss. It is what you do on a regular basis, 90% of the time, not 10% of the time that determines how you look, feel and age.
The intervention is almost embarrassingly straightforward: eat enough protein at every meal. Not just dinner. Breakfast and lunch matter just as much. In my opinion, breakfast is the most important meal for protein. Hit 30 to 40 grams three times a day, and your muscles fire the build signal three times a day instead of once.
If you choose not to bring this practice into your daily life, I will be saying it thorough out the years, every day in the gym to one member or other, and definitely stating it next year the 2027 SU4S campaign.
