How Protein Affects Metabolism: Impacts and Insights

A high-protein diet may help increase metabolic calorie burn by approximately 80-100 calories daily. Metabolism is a dynamic process, influenced by a number of inputs and individual factors. It is vital for basic life functions, breaking nutrients into usable energy, and cellular functioning.

Proteins are complex molecules of nutrients fundamental to metabolic processes. Protein intake affects the rates at which metabolism occurs and significantly influences body composition and overall health. This article will detail how protein affects metabolism and how recommendations for protein intake should be individualized to each person for optimal health outcomes. 

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What is Metabolism?

Metabolism is the basis of cellular function and is vital for life. It is a dynamic process influenced by many factors and changes significantly throughout the lifespan. Through a series of chemical reactions, metabolism includes two basic processes: catabolism and anabolism.

• Catabolism makes energy. It is the breakdown of nutrients, including carbohydrates, fats, and proteins, into usable energy to fuel various cellular activities. 
• Anabolism requires energy. It uses energy to make compounds necessary for cellular growth, repair, and maintenance. During the anabolic process, smaller molecules are combined to form complex compounds, like proteins, nucleic acids, and lipids, which play integral roles in cellular functioning. 

They allow for the continuous renewal, regeneration, and functioning of cells, tissues, and organs. This net energy balance between catabolism and anabolism impacts weight maintenance and nutrition status.

Protein Basics

Proteins are complex molecules, made up of amino acids, which are termed the building blocks of proteins. There are 20 total amino acids. Eleven amino acids are non-essential, as they can be made by the body. However, the other 9 are essential amino acids, meaning they must be obtained in the diet. 

Dietary sources of protein can be either animal-based or plant-based sources.

Common animal-based protein sources include:

• Meat
• Poultry
• Fish and seafood
• Eggs
• Dairy

Common plant-based protein sources include:

• Legumes
• Tofu
• Tempeh
• Nuts and seeds
• Grains

Protein's Role in the Body: 

Protein is an important macronutrient that is necessary for the growth and repair of tissues in the body. It is used to rebuild muscles and other vital structures, either with everyday activity or in events requiring major healing.

Other vital roles of protein include:

• Providing structure and strength to tissues
• Acting as enzyme catalysts for chemical reactions
• Serving as signaling molecules
• Transporting chemicals and neurotransmitters
• Synthesizing hormones
• Facilitating DNA replication

Protein's Impact on Metabolic Rate

Thermic Effect of Food (TEF): 

The body burns energy in the form of calories while digesting and metabolizing food as a process called the thermal effect of food. Different macronutrients require varying amounts of energy to metabolize. 

Protein has the highest thermic effect, as it requires the most energy for digestion (more than carbohydrates and fats). Prioritizing lean proteins, while still maintaining a balanced diet, may help support the overall metabolic rate, promoting weight management or healthy weight maintenance.

Muscle Mass and Metabolism: 

Dietary protein intake is required for growing muscle and maintaining strength. When adequate protein intake is combined with regular resistance training, muscle repair, and synthesis can promote muscle hypertrophy and strengthening. 

This may lead to an increased basal metabolic rate, as lean muscle mass can burn more calories than fat tissue, aiding in weight management and supporting overall metabolic health. Prioritizing dietary protein intake with appropriate physical activity may help regulate metabolism and improve body composition.

Protein, Weight Management, and Metabolic Health

Protein has important roles in weight management and metabolic health. Diets high in protein may be effective in weight management or healthy weight maintenance in several ways. 

• Protein may aid in appetite regulation by promoting fullness, potentially leading to a lower caloric intake overall. 
• Protein also helps preserve fat-free mass, which is more metabolically active, potentially burning additional calories at rest and contributing to a higher metabolic rate. 

Promoting an optimal body composition with balanced glucose levels may help reduce the risk of other proinflammatory metabolic conditions, like insulin resistance, prediabetes, metabolic syndrome, and obesity.

Protein Intake Recommendations

The daily amount of protein recommended varies by individual, from the low end of 0.8 grams per kilogram of body weight up to 2 grams per kilogram. Factors including body weight, activity level, age, and health goals help determine daily protein needs. 

• Athletes:  Competitive athletes may benefit from higher protein intakes of up to nearly 2 grams per kilogram. 
• Sedentary persons: Sedentary people require protein intakes on the lower end of the range, almost 1 g of protein per kilogram of body weight.
• Elderly:  Studies suggest that higher protein intakes may help mitigate sarcopenia, or muscle wasting with age, so older adults should be sure their protein intake is adequate.

Distributing protein intake evenly across the day has benefits such as: 

• Optimizing muscle protein synthesis and the metabolic advantages of protein intake. 
• Maintaining an adequate supply of amino acids in the bloodstream for muscle repair and growth, neurotransmitter signaling, hormone synthesis, and hunger control. 

Potential Risks of High Protein Diets

High protein intake often brings up concerns about kidney health. While healthy individuals usually tolerate higher protein diets without issue, individuals with preexisting kidney disease are often recommended to consume lower protein diets, as the kidneys are responsible for eliminating protein byproducts. Before changing your diet, consult your healthcare provider if you have underlying health concerns.

While one of the main functions of protein is maintaining bone and soft tissue strength and integrity, scientific evidence has suggested that excess protein intake can lead to increased calcium excretion. This may result in calcium breakdown from the bone to maintain serum calcium concentrations, potentially decreasing bone density. Conversely, other study findings have shown that high-protein diets actually have positive effects on bone density. 

Regardless, adequate calcium and vitamin D intake, along with protein intake, is essential to maintaining bone health and minimizing undesired bone remodeling.

Practical Tips for Incorporating Protein into the Diet

Incorporating healthy protein sources is important to maintain a balanced diet. Here are a few animal-based and plant-based meal ideas that are nutritious and high in protein.

Breakfast Protein Ideas

• Greek yogurt parfait, made with Greek yogurt, berries, and a sprinkle of almonds
• Scrambled tofu with fresh spinach and whole grain toast with avocado.

Lunch Protein Ideas

• Mixed greens topped with grilled chicken, lots of fresh vegetables, and a vinaigrette dressing made with extra virgin olive oil
• Lentil soup or vegetarian chili served with whole-grain bread

Dinner Protein Ideas

• Baked salmon filet paired with roasted vegetables and quinoa blend
• Black bean tacos with toppings of fresh salsa, corn, and guacamole on a bed of cilantro brown rice

For those following a vegetarian or vegan diet, ensure a plant-based protein source is part of every meal, and aim to combine a few different protein sources together to take in the necessary essential amino acids to form a complete protein. 

For example, combine brown rice and black beans, lentils and quinoa, or tofu and hummus. Fortified foods like plant-based milk alternatives can help replace calcium missing from dairy sources. Focus on nuts, seeds, and legumes to get healthy micronutrients on a daily basis.

Protein supplements, such as collagen peptides, whey protein, or plant-based proteins, can be helpful for individuals who are limited in the whole-food protein sources they can consume. They are available in shakes or powders and can be taken on their own, with other beverages, in smoothies or shakes, or added to other snacks.

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Key Takeaways

• Ensuring adequate protein intake is important for supporting metabolism and promoting overall metabolic health.
• Discuss personalized recommendations for protein intake with your healthcare professional. 
• Focus on nutrient-dense, lean protein sources as part of an anti-inflammatory eating plan. 
• Incorporate regular exercise, adequate sleep, and stress reduction to help keep metabolic processes running smoothly.