Proteins are one of the three important macronutrients. They form lean mass and are essential for several other physiological processes in the body, which is why ensuring adequate protein intake is crucial for health.
Online tools like a protein calculator helps estimate your daily protein requirement based on your height, weight, age, gender, and some other factors. In this post, we discuss protein as a nutrient, its importance, its association with weight loss, and how you can use a protein calculator to achieve your fitness goals.
What Is Protein?
Proteins are organic compounds made of small building blocks called amino acids. They are one of the three macros (i.e., nutrients that are consumed in large quantities and which act as primary sources of energy).
Proteins are found in all cells and tissues of the body but are mainly concentrated in the skin (keratin, collagen, elastin), bones (type 1 collagen), muscles (myoglobin, myogen, myoalbumin, and x-globulin), blood (albumin, globulins, hemoglobin), hair and nails (keratin).
There are 20 different amino acids, and they arrange themselves in unique combinations and patterns, forming 10,000 different proteins.
These 20 amino acids are classified into essential and non-essential based on their availability.
There are 11 non-essential amino acids that are synthesized naturally in the body. These are:
- Aspartic acid
- Glutamic acid
The rest of the nine essential amino acids are not made in the human body and, therefore, must be consumed in the diet. These are:
Importance Of Proteins In The Body
Adequate protein intake is extremely crucial for the body, as proteins are involved in several physiological processes. Additionally, they form the lean mass and are hence, important for activity.
Here are the eight main functions of proteins in the body and the associated health complications of protein deficiency:
Proteins are an important source of energy and a convenient source of nutrition. A gram of protein yields four calories, which is why a high-protein diet (and products like whey protein powder, protein shake, and protein supplements) is encouraged for bodybuilders and athletes for an instant energy dose.
Proteins are essential for growth. The research found a strong correlation between protein intake with better height and BMI in children aged one to nine years of age. Low protein intake is associated with stunted growth, which is seen in childhood diseases like Kwashiorkor.
Therefore, introducing proteins when a child starts weaning is recommended.
Additionally, proteins also play a role in the appropriate progression of puberty. However, it is crucial to mention that this applies to animal protein, as excessive protein from vegetable sources can delay development.
Hormone and Enzyme Synthesis
Proteins are important constituents of hormone and enzyme structure.
Enzymes are substances (body chemicals) that act as catalysts for biochemical reactions. They regulate metabolism and ensure it is carried out at a healthy rate.
Additionally, they are important for homeostasis, which is a regulatory mechanism that keeps the body physiologically stable, regardless of environmental effects.
Proteins also help form hormones, which are chemical messengers that travel in the blood, and signal target organs to carry out different tasks. They regulate blood pressure, sexual function, reproduction, fight and flight response, mood, appetite, weight, cold /heat tolerance, and several other functions.
All enzymes and hormones (except corticosteroids) are made of proteins.
Proteins provide structure to the cell and are important parts of the cell cycle. Structural proteins like globular or fibrillar proteins are found in cell walls and are also a crucial part of intercellular and intramolecular connections.
Other than that, proteins also form important body structures. In the hair, nails, and outermost layer of skin, they exist as keratin, which provides support, and also accelerates healing and repair in case of injury.
Similarly, collagen and elastin proteins are present in the skin to provide elasticity and to keep the signs of aging. Elastin also occurs in the lungs and helps them inflate and deflate, allowing maximum and healthy air exchange.
A complex protein called hemoglobin is present in red blood cells. When the blood travels through the lungs, hemoglobin binds to the inhaled oxygen and transfers carbon dioxide to the deoxygenated air for expiration.
The oxygen bound to hemoglobin is transported throughout the body and is used for energy.
Hemoglobin also binds to acids, and by virtue of this property, the protein helps regulate blood pH, keeping it at an optimum level, i.e., 7.4.
Variations in blood pH can lead to acidosis or alkalosis, which are associated with muscle loss, osteoporosis, confusion, muscle twitching, nausea, vomiting, numbness, paresthesia (pins and needle sensation), etc.
To avoid discomfort and health complications, maintaining pH is crucial, which is only possible through adequate hemoglobin levels.
Proteins are important for electrolyte balance. A liver protein called albumin maintains osmolarity and fluid balance in the body.
Low albumin levels in the blood can cause low calcium and sodium, which causes fatigue, weak muscle tone, peripheral swelling and edema, jaundice, appetite loss, and difficulty breathing.
Dietary proteins are crucial for the immune system, especially T cell function. T cells are a type of immune cells that initiate and maintain antigen-specific attack, which protects against foreign bodies and antigens.
Therefore, low protein intake makes you prone to infections. Additionally, protein deficit is also associated with increased severity of the disease.
Transport of Micronutrients
While macros (protein, carbohydrates, and fats) are the main sources of energy and nutrition, micronutrients like vitamins and minerals are also essential for the body. Absorption, transport, and storage of these micros are related to proteins and fats.
Prevention of Blood Loss
Proteins form clotting factors that help clot the blood at the site of the wound. In case of protein deficiency, clotting factors are not synthesized, which can lead to excessive blood loss and hemorrhage.
Complications Associated With Low Protein Intake
Protein deficiency refers to a condition when your protein intake fails to meet protein requirements in the body. It affects an estimated one billion people globally, especially in areas of Central Africa and South Asia.
Here are some of the signs and symptoms associated with low protein intake:
- Fatty liver disease
- Weak nails and hair
- Early aging signs in the skin
- Low lean body mass
- Weak bones
- Delayed development and stunted growth
- Increased risk of infections
- Excessive weight loss
Recommended Daily Protein Intake
While a protein calculator decides individual optimal daily protein intake, generally, adults are recommended 0.8 grams of protein for each kg of their body weight. For example, an individual weighing 100 kg should need approximately 80 grams of protein daily.
Through various calculations, recommended daily allowance (RDA) of proteins has also been devised for different ages and gender (discussed later).
Harmful Effects Of an Excess Protein Rich Diet
While we know the importance of proteins and the consequences of their deficiency, it is crucial to mention that excess protein intake is also associated with health complications.
When you consume more protein than what is needed for the body, the extra amounts are broken down and converted into fats in the liver. This fat is stored in the body as an energy reserve, and over the period, leads to obesity.
This results in a variety of health problems like hypertension (high blood pressure) and diabetes mellitus type 2.
Additionally, the extra protein also imposes a metabolic burden on end organs leading to metabolic syndrome, kidney disease, heart disease, etc.
Protein rich diets like red meat contain high amounts of saturated fat, which is unhealthy and increases low density lipoproteins (LDL) blood cholesterol. LDL is solid at room temperature, which is why high LDL increases the risk of atherosclerosis (fatty deposits and blockage of coronary arteries).
We know that protein intake is directly related to growth hormone synthesis and release. In case of excess proteins, excessive levels of growth hormone and insulin growth factor (IGF-1) are released. This does not only cause the multiplication of normal cells but can also lead to the abnormal proliferation of cancerous cells.
Sources of Protein
Proteins are found abundantly in natural food. Plant-based proteins can be found in the following foods:
- Soy products
- Peanut butter
- Chia seeds
Products like protein shake, protein powder, and protein supplements can also help incorporate more protein in diet to help gain muscle and lean mass.
The following are the sources of animal proteins:
- Cottage cheese
- Meat (especially beef)
Here is the protein content present in major protein sources:
- 100 gm beef meat = 26 gm protein
- 100 gm poultry = 11 gm protein
- 100 gm egg = 13 gm protein
- 100 gm soy milk = 3.3 gm protein
- 100 gm legumes (raw pinto beans) = 21 gm protein
Here, it is important to mention that animal protein is generally considered better than proteins consumed through vegetarian diets. Animal proteins stimulate the muscle protein synthesis and breakdown, which increases lean muscle mass.
This improves strength and energy levels in an individual.
On the other hand, plant proteins lack essential amino acids like leucine (involved in tissue regeneration and metabolism). Additionally, they are also associated with lower digestibility, which can result in protein deficiency.
A healthy percentage of animal and protein is not defined. However, it is generally recommended to include eggs, meat, and poultry as major protein sources in your daily 10 to 35% ideal protein intake.
How Does a Protein Intake Calculator Work?
A daily protein calculator estimates how much protein you need daily. It is based on several factors like age, gender, height, weight, and physical activity.
Age is one of the most critical factors involved in body composition variations and nutrition requirements. As we age, muscle mass is gradually lost due to a decline in metabolic rate. Every ten years after you hit 20, metabolism slows down by 2 to 3%.
Hence, fats are burned at a slower rate, which enables a high body fat mass, thus leading to obesity. Additionally, as you grow old, your risk of developing metabolic syndrome, kidney disease, heart complications, liver disease, and infections gradually increases.
Weakening of the immune system further exacerbates the problem. Bone disease is also another issue that occurs with muscle loss, impaired liver function, and electrolyte imbalance as a result of low dietary protein intake.
For all these reasons and more, high protein intake is recommended in older adults.
As we discussed in growing children and young adults too, proteins are required for growth, as they stimulate the formation and release of the growth hormone. While protein deficit can cause delayed development and stunted growth, excess protein intake in children is also associated with health problems.
To ensure optimal protein intake, recommended dietary allowance (RDA) of proteins has been assigned to each age group.
- Age 1 to 3 = 13 gm
- Age 4 to 8 = 19 gm
- Age 9 to 13 = 34 gm
- Age 14 to 18 (girls) = 46 gm
- Age 14 to 18 (boys) = 52 gm
- Age 19 to 70 (women) = 46 gm
- Age 19 to 0 = 56 gm
Another factor affecting protein requirement and daily protein allowance is gender.
Body composition varies for each gender. While men have higher muscle mass and low body fat (due to fast metabolic rate), women have low muscle mass.
However, the difference in metabolic rate for both men and women is what mainly determines protein intake. We know that men have better metabolism when it comes to macros than women. Due to this, women are also at risk of developing obesity in case of eating a high-protein diet.
Therefore, men are recommended more protein in diet than women.
Your height and general body surface determine your caloric needs, and hence are important variables of protein calculator. Therefore, results of protein intake allowance will vary for people of different heights.
Someone of short stature understandably needs fewer proteins than a tall person.
BMI and Body Weight
Your body weight and BMI are crucial defining factors for protein. Each person has a normal, healthy weight that corresponds to the lowest risk of health disorders and mortality. This ideal body weight is based on an individual’s gender, age, height, and physical activity.
Your current weight is measured against your normal weight through several different calculations, the most popular of which is body mass index or BMI.
BMI is essentially a ratio of your weight (in kg) and height (in m2).
The results are classified into four categories:
- Underweight = < 18.5
- Normal weight = 18.5 to 24.9
- Overweight = 25.0 to 29.9
- Obese = > 30
If your current weight falls in the overweight or obese category, your daily protein intake would be generally low to restrict overall calories. This allows your body to utilize and burn stored fat for energy, which helps you lose weight.
Physical Activity Level
We know that proteins are an energy source. Physical activity affects your metabolism and determines your energy requirements, basal metabolic rate (BMR), and total daily energy expenditure (TDEE), which directly defines your protein requirement.
A person who is involved in intense physical labor needs more energy to function (high total daily energy expenditure), will have better metabolism, and would thus need more proteins.
On the other hand, anyone who leads a comparatively inactive lifestyle needs to restrict their calorie intake to minimize the risk of accumulating body fat and developing obesity.
Therefore, a protein calculator asks you to specify your activity level.
In clinical nutrition, there are six levels of physical activity:
- Sedentary: Little to no exercise
- Light: Exercise 1 to 3 times a week
- Moderate: Exercise 4 to 5 times a week
- Active: Daily exercise or extreme exercise 3 to 4 times a week
- Very Intense: Daily extreme exercise
- Extra Active: Very intense exercise daily or a physical job
In the above classification:
- Exercise – 15 to 30 minutes of increased heart rate
- Extreme /Intense exercise – 45 to 120 minutes of high heart rate
- Very intense exercise – 2+ hours of increased heart rate
Pregnancy and Lactation
Apart from the five important variables of the protein calculator discussed above, there are certain other factors that are considered on a protein calculator. Of them, the most important are pregnancy and lactation.
Pregnant women need a little more protein content than normal in diet to support the developmental changes in their own bodies, as well as that of the baby.
According to dietary reference intakes, pregnant women need 0.8 g protein per kg of body weight, plus an extra 6 grams of protein per day.
In lactating mothers, on the other hand, the protein requirement is slightly lower because breast milk is rich in protein, and excess dietary protein can cause health complications in the baby. Typically, 15 g to 20 g of daily protein is recommended during lactation.
Protein For Muscle Growth
We know that proteins are an important part of muscle anabolism (help build muscle). Therefore, high protein diet is associated with greater lean muscle gain. Taking protein foods along with resistance training and similar kinds of exercises can help lose fat and unhealthy weight.
Use a protein calculator to estimate your protein needs, and make sure to incorporate the resultant value in your daily diet through high protein foods.
Along with all this, maintaining a healthy lifestyle, and eating a balanced diet having all macros in adequate amounts is also important.