Protein: More Than Just a Macronutrient

By Gabrielle Lyon, MD, November 28, 2023

Dr lyon protein feature

In the complex symphony of the human body, proteins take center stage. While they make up only a portion of the body's composition, their role extends far beyond building muscles and tissues. Proteins are the master regulators of vital physiological processes. In this article, we will delve deep into the multifaceted world of protein, exploring its significance for longevity, metabolic function, and overall well-being.


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Beyond building muscle: The multi-faceted power of protein

Proteins are more than the bricks and mortar of the body. Here's a brief overview of their diverse functions:

  1. Enzyme synthesis: Proteins are the architects of biochemical reactions in the body. They synthesize enzymes, molecules that catalyze vital chemical processes necessary for survival.
  2. Energy production: Proteins play a crucial role in energy metabolism. They contribute to the production of adenosine triphosphate (ATP), the cell's energy currency.
  3. Hormone regulation: Many hormones are composed of proteins. For example, insulin, which regulates blood sugar, and thyroid hormones that influence metabolic rate, are made up of amino acids provided by proteins.
  4. Immune function: Antibodies, the soldiers of the immune system that neutralize pathogens, are proteins. They are essential in defending the body against infections and diseases.
  5. Neurotransmitter production: The brain relies on protein-rich foods to produce neurotransmitters such as dopamine and serotonin - chemicals crucial for neurological development, mood regulation, and sleep.

The benefits of a protein-forward diet

A protein-forward nutrition plan can have numerous advantages, including:

  1. Balanced blood sugar: High-quality protein sources have a lower glycemic index, leading to more stable blood sugar levels. This can help prevent diabetes and maintain optimal glucose control [1
  2. Increased energy: Protein-rich foods have a higher thermic effect, meaning they require more energy for digestion and metabolism. This can boost overall energy levels and assist in weight management. [2]
  3. Mental clarity: Consuming enough protein supports the production of neurotransmitters crucial for brain function. This can enhance cognitive performance and mood regulation. [3]
  4. Improved body composition: Protein promotes satiety and reduces cravings, making it easier to adhere to a calorie-restricted diet and lose excess body fat. [2] Adequate protein intake helps build and preserve lean muscle mass, promoting a healthy body composition.

By now, it's clear that protein is the linchpin of optimal health and longevity, far surpassing its role in muscle building. However, a critical issue remains: the widespread misunderstanding of dietary requirements for protein. This misunderstanding is perpetuated by outdated recommendations. [4]


The quality of protein: Rethinking dietary guidelines

The Recommended Dietary Allowance (RDA) for protein in the United States is set at 0.8 grams of protein per kilogram of body weight per day. For a person weighing 150 pounds, this translates to about 54 grams of protein daily (46 grams for women and 56 grams for men). However, these numbers are based on antiquated methods designed for animal agriculture and significantly underestimate the actual protein requirements.

According to what I’ve seen in clinical practice and the current scientific literature, a more accurate guideline, the “Lyon RDA”, recommends that adults consume 1g per lb of ideal body weightmore specifically 30 to 50 grams of high-quality protein per primary mealto optimize health and longevity. This figure, while seemingly high, takes into account not only the minimum requirements for survival but also the goals of muscle protection and long-term thriving.

Unveiling the amino acid spectrum

Protein is often viewed as a monolithic macronutrient. However, it's essential to recognize that it serves as a delivery system for twenty distinct amino acids, each with a dual role: supporting physical structures and fueling physiological functions. These amino acids fall into three categories:

  1. Nonessential amino acids: The body can produce these amino acids if sufficient total protein is consumed.
  2. Conditionally essential amino acids: In certain conditions like illness or injury, the body cannot synthesize enough of these amino acids and relies on dietary sources.
  3. Essential amino acids: These must be obtained directly from the diet because the body cannot produce them.

Of the essential amino acids, three are especially critical: leucine, lysine, and methionine. These amino acids are essential not just for muscle health but for a range of functions. Leucine, in particular, is vital for stimulating muscle protein synthesis, a key process for maintaining and building muscle tissue.

What is an "incomplete protein"?

Perhaps you’ve heard the term “incomplete protein” used to describe foods that are missing, or contain limited quantities of, one or more of the essential amino acids in amounts necessary for human health. Legumes are a prime example. While they contain lysine, threonine, and tryptophan, legumes lack methionine. Grains, meanwhile, contain methionine but provide limited lysine and often limited threonine or tryptophan. Combined, legumes and grains supply a mixture of amino acids of higher quality than either one alone.

Such combinations are said to supply complementary proteins which, together, provide a full amino acid profile. Still, these combinations are not as complete as the protein in meat, milk, eggs, or fish, which contain all the essential amino acids needed for sufficient protein intake.

Aging and protein needs

Protein requirements change over a lifetime, with age playing a significant role. Children, for instance, require a different amount of protein than older adults. While children can trigger muscle protein synthesis with as little as 5 to 10 grams of protein, older adults may need at least 2.5 grams of leucine per meal to achieve the same effect. [5] This requirement, equivalent to around 30 grams of high-quality protein per meal, becomes essential to combat age-related muscle loss. By age seventy-one and up, only half of women and about 30 percent of men reach RDA protein levels. [5

Adopting a protein-forward nutrition plan can help prevent and manage various chronic diseases by stabilizing blood sugar, reducing inflammation, supporting weight management, maintaining bone health, and promoting muscle retention. High-quality protein sources play a crucial role in disease prevention, supporting immune function, and contributing to overall longevity.

Sample meal plan for more proteinMeal timing for muscle optimization

Protein timing can significantly impact muscle health. Breakfast, whether it's your first meal of the day or not, plays a crucial role in setting the stage for metabolic optimization. A substantial protein intake during breakfast stimulates muscle growth, reduces hunger, and provides amino acids for essential biological functions. [6]

The last meal before your overnight fast is equally important. A dose of protein at this meal can help stabilize blood sugar levels throughout the night and prepare your body for the morning. For example, consuming casein protein before bedtime can increase overnight muscle protein synthesis and metabolic rate without interfering with fat burning during sleep. [1]


Protein's superpowers: Thermogenesis and satiety

The thermic effect of protein is high

Protein has a higher thermic effect compared to carbohydrates and fats, which means it requires more energy for digestion and metabolism. While protein is traditionally counted as providing 4 calories per gram, the actual energy expended during the digestion and assimilation of protein can amount to 20 to 35 percent of its net caloric intake. This means that you effectively burn more calories when consuming protein, making it seem as if you've eaten fewer calories overall.

Consuming protein promotes satiety

Another remarkable benefit of prioritizing protein in your diet is its impact on satiety, the feeling of fullness. Clinical trials have consistently shown that high-protein diets are more satiating, making it easier to adhere to a calorie-restricted diet and lose body fat. Consuming adequate protein throughout the day can act as a natural appetite suppressant, aiding in weight management. Protein-rich foods increase the release of gut hormones which promote a feeling of fullness. Simultaneously, they reduce the hunger hormone, ghrelin, helping to control appetite. [7,8]

We have a natural drive to prioritize protein

Humans and many other animal species exhibit protein prioritization. This means that they will continue eating until they've consumed an adequate amount of protein, even if they have to overeat in terms of non-protein energy, such as carbohydrates and fats. By maintaining a high percentage of protein in your diet, you'll naturally eat fewer overall calories.

How do I know how much protein I'm eating?

In practice, many individuals fall short of their protein needs, often without realizing it. To determine your protein intake accurately, consider keeping a food log and using a food scale to measure your daily consumption. Even if you are not currently deficient in protein, you may still be far from protein optimization unless you have consciously tailored your diet to prioritize protein quantity, quality, and distribution.

Protein power moves: 

  1. Prioritize protein in meals: Begin your meals with protein to ensure you consume essential amino acids that drive muscle protein synthesis and promote satiety.
  2. Preempt unhealthy food choices: Before attending an event with unhealthy food options, consume a 20-gram protein shake to curb cravings and resist temptations.
  3. Swap snacks for protein chips: Replace high-calorie, low-nutrient snacks with protein-rich options like protein chips.
  4. Balance low-protein meals: Add essential amino acids to water to counterbalance low-protein meals, supporting muscle metabolism and preventing blood sugar spikes.

Protein is key to a healthy life

In support of health and longevity, proteins take on a starring role far beyond their function in building muscles. By prioritizing protein in your diet, you can achieve a myriad of benefits, from balanced blood sugar and increased energy to mental clarity, reduced body fat, and improved body composition. Both the quantity and quality of protein matter, with essential amino acids playing a pivotal role in your health. 

As you navigate the overwhelming amount of information about nutrition, remember that protein is not your enemy but your ally. It's the key to not only maintaining muscle mass and a healthy body composition, but also supporting vital bodily functions that impact your longevity and quality of life.  Let protein be your guide on the path to a longer, healthier future and remember that muscle is the organ of longevity ®.


  8. Heather J. Leidy, Richard D. Mattes, and Wayne W. Campbell, “Effects of Acute and Chronic Protein Intake on Metabolism, Appetite, and Ghrelin during Weight Loss,” Obesity 15, no. 5 (2007): 1215–1225.

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