I have been waiting for this conversation for a very long time.

In this episode, I sat down with two of the most important protein scientists in the world: Dr. Donald Layman, my mentor of 25 years, and Dr. Heather Leidy, whose work has shaped how we think about protein, breakfast, satiety, and metabolism. We came together to discuss one of the biggest changes in American nutrition policy in decades: the 2025–2030 Dietary Guidelines for Americans.

For the first time, protein is no longer treated like an afterthought.

That may sound small, but it is not. For decades, nutrition guidance has largely been organized around what to avoid: saturated fat, cholesterol, sodium, sugar, and calories. The new guidelines shift the starting point. They tell Americans to prioritize whole, nutrient-dense foods, including protein, dairy, vegetables, fruits, healthy fats, and whole grains, while dramatically reducing highly processed foods, refined carbohydrates, added sugars, excess sodium, and unhealthy fats. The guidelines also include a protein serving goal of 1.2 to 1.6 grams per kilogram of body weight per day, adjusted for individual calorie needs.

That is a major change.

But it has also created controversy, confusion, and a lot of misunderstanding. So this conversation was about clarifying what changed, what did not change, what protein actually does in the body, and how people should think about building a diet from real food rather than ideology.

The RDA Is Not The Same As An Optimal Goal

One of the biggest misunderstandings around protein is the RDA.

The RDA for protein is still 0.8 grams per kilogram of body weight per day. That did not change. But the RDA is not the same thing as an optimal target for body composition, satiety, nutrient density, aging, or metabolic health. 

It is a minimum reference value, and it was established using nitrogen balance studies. That matters because nitrogen balance is a very limited way to think about protein needs in a living, aging, active human being. These studies often measure protein requirements after the body has already adapted to lower protein intake. And the body is very good at adapting to scarcity. It can downregulate processes like muscle protein turnover, immune function, and other metabolically expensive systems in order to survive on less.

But surviving on less is not the same as thriving.

That is why I think the new guidelines are so important. They are not saying the RDA changed. They are saying that a healthy protein intake goal may be higher than the minimum. The 1.2 to 1.6 gram per kilogram range sits well within the broader acceptable macronutrient distribution range (AMDR) for protein, which has long been 10–35% of calories. 

This is where I think clinicians and consumers get stuck.

 

They hear, “Americans already get enough protein,” and they assume the conversation is over. But “enough to avoid deficiency” is not the same as enough to preserve lean mass during weight loss, support training, reduce cravings, maintain function with aging, or meet essential amino acid needs with a margin of safety.

 

More modern methods, including the Indicator Amino Acid Oxidation method, or IAAO, suggest that true physiological protein needs may be closer to 1.2 grams per kilogram per day for many healthy adults. That is about 50 percent higher than the current RDA. And that is before we even start talking about athletes, weight loss, injury, illness, GLP-1 use, or aging-related anabolic resistance.

 

There is also a very important metabolic ward study that makes this point hard to ignore. Participants were overfed by 40% above their calorie needs while consuming different amounts of protein: 0.7, 1.8, or 3.0 grams per kilogram per day. Everyone gained fat because everyone was overfed, but only the higher-protein groups gained lean mass, about 6 to 7 pounds. The group consuming 0.7 grams per kilogram, which is close to the RDA, actually lost about 1.5 pounds of lean mass despite being in a calorie surplus.

 

If protein near the RDA cannot preserve lean mass even when calories are abundant, we should be very careful about telling people it is automatically enough during dieting, aging, illness, or appetite suppression.

 

For active individuals, the evidence generally supports higher intakes. The International Society of Sports Nutrition and the American College of Sports Medicine both recognize that athletes and physically active adults often benefit from protein intakes well above the RDA, commonly in the range of 1.6 to 2.2 grams per kilogram per day, depending on training, goals, and energy intake. 

 

For endurance athletes and bodybuilders, protein needs are higher due to greater demands on muscle repair and recovery. Studies using the IAAO method suggest that endurance athletes require 1.4 g/kg (men) or 1.7 g/kg (women) of protein daily, with post-exercise needs potentially reaching 2.6 g/kg. For amateur bodybuilders, 2.2 g/kg on non-training days may be required to maximally support muscle retention and growth.

 

This also becomes critical with aging.

 

The RDA remains 0.8 grams per kilogram for adults over 50, but IAAO studies suggest that 1.2 grams per kilogram may be a more appropriate baseline for both younger and older adults, including men and women over 65 and even women in their 80s. Many expert groups now recommend roughly 1.2 to 1.5 grams per kilogram for older adults to support muscle maintenance, strength, function, and resilience.

 

As we age, the cost of under-eating protein becomes much higher. We are not just talking about macros. We are talking about the ability to maintain muscle, recover from illness, prevent frailty, support bone, preserve independence, and continue participating in life.

 

And the evidence supports this. Doubling protein from 0.8 to 1.6 grams per kilogram has been shown to increase lean body mass in older men. In older women, even moving from about 0.9 to 1.4 grams per kilogram has improved body composition and helped preserve lean mass. Even modest increases, such as moving from 1.0 to 1.3 grams per kilogram, can matter when the goal is to maintain muscle and metabolic health over time.

 

Dr. Layman made a point in this conversation that I think every clinician should hear: there is not a single study showing that 0.8 grams per kilogram is better than higher protein intakes above roughly 1.1 grams per kilogram for meaningful health outcomes. Sometimes higher protein shows a clear benefit. Sometimes it shows no difference. But the argument that the RDA is superior is not supported by evidence.

 

That is the shift. We are moving from minimum survival thinking to optimal function thinking. And for most adults, especially active people, older adults, and anyone trying to improve body composition, the better question is not, “Did I hit the RDA?” The better question is, “Am I eating enough high-quality protein to support the body I want to live in?”

 

Protein Is More Than Muscle

I have spent much of my career talking about muscle, so naturally, people assume I care about protein only because of lean mass. But protein is not just a muscle nutrient.

 

Protein delivers essential amino acids. Those amino acids are used for muscle protein synthesis, yes, but they also support neurotransmitters, immune function, antioxidant systems, connective tissue, enzymes, hormones, and countless metabolic processes. Leucine is a signal for muscle protein synthesis. Tryptophan is a precursor for serotonin. Phenylalanine and tyrosine relate to dopamine. Methionine and cysteine matter for glutathione, one of the body’s major antioxidant systems.

 

This is why I get concerned when protein is reduced to one question: “Did it increase lean body mass in a 12-week trial?” That is too narrow.

 

A short trial may not show a large change in muscle mass, especially in free-living older adults. That does not mean protein is irrelevant. It may mean the study was too short, the outcome was too blunt, the participants were not under the right stressor, or the real benefit was showing up somewhere else.

 

When protein is tested under conditions where the body is actually vulnerable, the benefits become much clearer.

 

During calorie restriction, for example, higher protein helps protect lean tissue. In one randomized controlled trial, adults consuming protein above the RDA during a calorie deficit lost the same amount of body weight as the RDA group, but a lower proportion of that loss came from fat-free mass and a greater proportion came from fat mass.

 

We also see this in aging. Other meta-analyses have found that higher protein intake is associated with a lower risk of developing frailty and better physical function, especially when protein intake is above about 1.2 grams per kilogram per day. So if you are over 50, protein is not something to be casual about. It becomes one of the nutritional levers that helps protect strength, independence, and physical capacity.

 

Protein also matters for cardiometabolic health. A meta-analysis of 74 studies found that higher-protein diets significantly reduced several cardiometabolic risk factors, including waist circumference, blood pressure, and triglycerides, while also increasing satiety. That matters because protein is not only helping preserve muscle. It can also help people manage hunger, improve body composition, and reduce some of the risk factors that travel with overweight and obesity.

 

This is especially important right now because we are in the GLP-1 era.

 

Millions of people are losing weight with medications that powerfully reduce appetite. These drugs can be extraordinary tools, but weight loss is never just fat loss. Clinical trials consistently show that a meaningful portion of weight lost on GLP-1s comes from lean mass and other non-fat tissue. In STEP 1, roughly 39–40%of the weight lost came from lean mass. SUSTAIN-8 and SURMOUNT-1 showed similar patterns, with about 25–40% of lost weight coming from non-fat mass.

 

To be fair, that is not radically different from traditional dieting, where roughly 20–30% of weight loss often comes from lean mass. But it is still a major concern. If someone loses weight but also loses muscle, strength, bone-supporting tissue, and functional reserve, we have not solved the real problem.

 

One of the reasons this happens is simple: people undereat protein. GLP-1s suppress appetite so effectively that many people unintentionally eat less of everything, including the one macronutrient they most need to protect lean tissue. Most of the major trials also involved sedentary people who were not necessarily prioritizing high-quality protein or resistance training, which are two of the most important tools for preserving muscle during weight loss.

 

This is why protein must be central to any fat loss strategy. Whether you are using a GLP-1 or not, the goal is not just to lose weight. The goal is to lose fat while preserving the tissue that keeps you strong, metabolically healthy, and capable.

 

We can see how powerful this principle is in the protein-sparing modified fast. The PSMF is an extreme calorie-restricted diet designed to mimic fasting while preserving muscle through high protein intake, essential nutrients, and very low calories. In one study of nearly 1,400 adults with obesity consuming only 600 to 800 calories per day, participants lost about 27 pounds in three months, but only about 4.5 pounds came from lean mass. That is roughly 16 percent of total weight lost, a far better lean-mass preservation ratio than what is commonly seen when weight loss occurs without adequate protein and training support.

 

That does not mean everyone should do a protein-sparing modified fast. It means that when calories go down, protein needs go up in importance. This is the framework I want people to understand. Protein is not just about building bigger muscles. It is about preserving the body’s functional tissue under stress: aging, dieting, illness, injury, appetite suppression, and metabolic disease.

 

Protein Quality Matters

Another point that gets lost is protein quality.

 

The body does not have a generic “protein” requirement as much as it has requirements for essential amino acids. Protein foods are the delivery system.

 

That means 30 grams of protein from different foods may not mean the same thing physiologically. The amino acid profile, digestibility, food matrix, micronutrients, and calorie load all matter. This is why the FAO has recommended the Digestible Indispensable Amino Acid Score, or DIAAS, as a protein quality method. DIAAS evaluates digestible indispensable amino acids, not just crude protein on a label.

 

That distinction is critical.

 

Animal-based proteins such as eggs, poultry, fish, beef, Greek yogurt, and whey are often considered the gold standard because they provide all nine essential amino acids in highly usable amounts and tend to be highly digestible, often with digestibility above 90%. They also come packaged with nutrients that matter for human health: iron, zinc, B12, calcium, iodine, choline, creatine, carnosine, and other compounds that are difficult to replace when animal foods are reduced.

 

Plant proteins can absolutely be part of a healthy diet. Beans, peas, lentils, nuts, seeds, vegetables, and whole grains can all contribute valuable nutrients, including fiber, folate, magnesium, potassium, and phytonutrients. The new guidelines emphasize vegetables, fruits, high-fiber foods, fermented foods, legumes, and whole grains for good reason.

 

But we have to be honest about the tradeoffs.

 

Most plant proteins are lower in one or more essential amino acids, less digestible, and often lower in leucine, which is one of the key amino acids that helps stimulate muscle protein synthesis. Legumes and grains, for example, often have lower digestibility, partly because of anti-nutrients such as phytates and tannins that can interfere with protein absorption. Cooking helps reduce these compounds, but it does not always eliminate them completely.

 

This is one reason plant-based protein powders can perform differently than whole plant foods. Pea, soy, and other plant protein isolates often have improved digestibility because they have been processed to concentrate the protein and remove some of the interfering compounds. That does not make them identical to whey or animal protein, but it does make them more effective than relying on low-protein whole plant foods alone.

 

The issue becomes especially important when we talk about muscle.

 

All 20 amino acids are needed to build muscle, but the essential amino acids, and particularly leucine, are the primary drivers of muscle protein synthesis. This is one reason studies often show lower muscle protein synthesis after consuming soy compared with whey, milk, or lean beef. This can impact lean mass gains, especially when consuming modest doses of protein (around 20 grams).

 

That does not mean plant proteins cannot work. It means dose and planning matter.

 

When plant proteins are consumed in higher amounts, often 33 to 50 grams or more, they can produce similar lean mass gains as animal proteins in some studies. In other words, you can often offset lower protein quality with a higher total dose. But that comes with practical tradeoffs: more food volume, more calories, more carbohydrates, more fiber, and sometimes more digestive burden.

 

There is also the issue of limiting amino acids.

 

A limiting amino acid is an essential amino acid present in such a small amount that it bottlenecks the body’s ability to build new proteins. Grains like wheat and rice tend to be limited in lysine. Beans and legumes are often lower in methionine and cysteine. This is why combining plant proteins, such as rice and beans, can improve the overall amino acid profile of a plant-based diet. But again, this requires intention.

 

If someone reduces animal-source protein and replaces it mostly with grains, which is what often happens in real-world dietary patterns, they may reduce the essential amino acid density of the diet. That matters for everyone, but it matters most for the people who can least afford to miss: older adults, adolescent girls, pregnant and lactating women, athletes, people dieting, and people using appetite-suppressing medications.

 

This is not an argument against plant foods. It is an argument against pretending all protein sources are interchangeable. A cup of cooked beans is not the same as a scoop of whey. A slice of bread with “protein” on the label is not the same as eggs. Thirty grams of protein from a high-quality animal source is not automatically equivalent to 30 grams of protein from a lower-digestibility plant source.

 

Choose high-quality protein foods first. Then build the rest of the diet around nutrient density, fiber, healthy fats, vegetables, fruits, legumes, and the person’s metabolic needs. For someone who chooses a vegetarian or vegan pattern, that means being more intentional about total protein, protein quality, complementary amino acids, and potentially using higher-quality protein supplements or essential amino acids when appropriate.

 

Protein quality matters because the body is not reading the front of the package, but instead responding to the amino acids, digestibility, nutrient matrix, and total metabolic context of the meal.

 

Breakfast Is A Missed Opportunity

Dr. Leidy’s work on breakfast is one of the most practical parts of this conversation.

 

A lot of people skip breakfast because they are busy, not hungry, or used to starting the day with coffee. Teenagers often skip because they want to sleep as late as possible. But when breakfast is built correctly, especially with higher-quality protein, it can change appetite and behavior later in the day.

 

In one of Dr. Leidy’s studies, a higher-protein breakfast in overweight teen girls reduced brain responses to visual food cues in regions related to food motivation and reward. The takeaway is important: cravings are not always a failure of discipline. Food choices earlier in the day can change the brain signals that drive hunger, reward, and overeating later.

 

Her work also showed that higher-protein breakfasts improved appetite control, satiety, food motivation, reward, and evening snacking compared with skipping breakfast in overweight or obese breakfast-skipping adolescent girls.

 

This is why breakfast matters, especially for children and adolescents.

 

The new guidelines highlight adolescence as a period of rapid growth with increased needs for energy, protein, calcium, and iron, especially for girls due to menstruation. They also recommend nutrient-dense foods such as dairy, leafy greens, and iron-rich animal foods while limiting sugary drinks, energy drinks, and highly processed foods.

 

If the first meal of the day is ultra-processed carbohydrate with very little protein, we should not be surprised when hunger, cravings, energy instability, and poor nutrient adequacy follow.

 

Saturated Fat Is Still The Sticking Point

The saturated fat recommendation did not change. The new guidelines still say saturated fat should generally not exceed 10 percent of total daily calories, while also acknowledging that more high-quality research is needed to determine which types of dietary fats best support long-term health.

 

This is where a lot of the controversy lives.

 

For decades, saturated fat has been used to demonize specific foods: eggs, red meat, full-fat dairy, and other animal-source foods. But the new framework is more food-pattern based. It does not say every food containing saturated fat is automatically unhealthy. It says to prioritize nutrient-dense foods and keep the whole dietary pattern in mind.

 

That is the right direction.

 

If saturated fat matters for a given person, the question should be: where is it coming from, what is it replacing, and what is the person’s overall cardiometabolic risk?

 

Saturated fat from a ribeye in a whole-food diet is not the same conversation as saturated fat from cookies, pastries, packaged snack foods, and ultra-processed desserts. The new guidelines explicitly recommend avoiding highly processed packaged foods that are salty or sweet, such as chips, cookies, and candy, and instead prioritizing nutrient-dense foods and home-prepared meals.

 

That is a much more useful conversation than simply telling people to fear real foods. A healthy diet can include protein foods, dairy, eggs, seafood, vegetables, fruits, healthy fats, legumes, and whole grains. The details should be individualized.

 

Do Not Let Protein Become Another Health Halo

There is one place where I want people to be careful. Now that protein is finally being emphasized, the food industry is going to do what the food industry always does: put protein on everything.

 

Protein popcorn. Protein cereal. Protein cookies. Protein coffee. Protein desserts.

 

Some of these may be useful. Many will be junk food with protein fairy dust.

 

This is where we have to stay grounded. Protein on a label does not automatically make something a protein food. Dr. Layman’s practical threshold is useful: if a food has less than about 10 grams of protein per serving, do not think of it as a meaningful protein source. And even when a food has more than that, look at the source of protein, total calories, added sugar, fiber, and whether it actually helps you build a better dietary pattern.

 

A scoop of protein powder, essential amino acids, or a higher-protein snack can be useful in specific situations like older adults with low appetite, people using GLP-1 medications, athletes, pregnant or lactating women, people recovering from illness, or someone who simply cannot hit their protein needs with whole foods. But supplements should support the diet, not replace the diet.

 

The point is not to protein-fortify ultra-processed food and pretend the problem is solved. The point is to build meals around nutrient-dense protein foods and then use tools strategically when needed.

 

Action Checklist

Start with protein at each meal. Use the new guideline range of 1.2 to 1.6 grams per kilogram per day as a practical goal, adjusted for body size, calorie needs, age, training, and health status.

 

Do not confuse the RDA with optimal intake. The RDA is a minimum reference value. It is not the ceiling, and it is not necessarily the best target for body composition, satiety, aging, or metabolic health.

 

Think in meals, not just daily totals. For many adults, 25 to 40 grams of high-quality protein per meal is a useful practical range.

 

Prioritize protein quality. Eggs, dairy, meat, poultry, seafood, and high-quality supplemental proteins provide dense essential amino acids. Plant proteins can work too, but they often require more planning and more total food volume.

 

Protect protein during weight loss. If you are dieting, using a GLP-1, or losing weight rapidly, protein and resistance training become non-negotiable.

 

Do not ignore breakfast. A higher-protein breakfast can help appetite control, cravings, and food reward later in the day.

 

Keep vegetables, fruits, legumes, and fiber in the diet. A protein-forward diet is not a fiber-free diet. It should be nutrient-dense across the board.

 

Do not fear real food because of outdated narratives. Eggs, dairy, meat, seafood, vegetables, fruits, legumes, and whole grains can all fit into a healthy pattern.

 

Be skeptical of “protein” junk food. If it has one or two grams of protein and a protein claim on the package, that is marketing, not nutrition.

 

Use supplements strategically. Essential amino acids, whey, or other protein supplements can be helpful when appetite, schedule, age, illness, training, or medication makes whole-food intake difficult.