All about protein intake: How much protein should you eat?

Protein is the most satiating macronutrient.

So, it makes sense that increased protein intake usually involves a spontaneous reduction of calories eaten and eventually, weight loss. (Study, Study)

But how much protein should you eat everyday?

Although we don’t necessarily require a high protein intake in a healthy diet, due to its normalizing effect on body weight, many people wonder how much daily protein can be consumed in a healthy way.

Following the post we did about carbohydrates, this week we’ll review the main characteristics of proteins.

What is protein

Protein is derived from the Greek word meaning “first one” or “most important one.” In our bodies, about 40% of our protein is in our muscles and organs, with about 25% in our skin and blood.

The molecules that make up proteins are called amino acids (AA). There is a basic set of 20 amino acids, of which 9 are essential (i.e. the body can’t synthesize them).

Essential Nonessential
Isoleucine (Ile) Alanine (Ala)
Leucine (Leu) Tyrosine (Tyr)
Lysine (Lys) Aspartic acid (Asp)
Methionine (Met) Cysteine (Cys)
Phenylalanine (Phe) Glutamic acid (Glu)
Threonine (Thr) Glutamine (Gln)
Tryptophan (Trp) Glycine (Gly)
Valine (Val) Proline (Pro)
Histidine (His) Serine (Ser)

Arginine (Arg) (essential only  for children)

 Asparagine (Asn)

Functions of proteins

We often think of protein only as raw material for tissue building, but we must consider its other roles: as enzymes, proteinaceous hormones, pH regulators, and part of the body’s defensive response. A protein deficiency affects our whole body’s physiology.

How much protein should you eat

The recommended amount of protein can vary greatly depending on the body type, lifestyle, and needs of each person.  Someone who works in an office, seated all day, another person who works as a lifeguard and a third who suffers from an autoimmune disease (remember that proteins play an important role in our defenses) will all have greatly varying needs for protein in their daily diets.

It’s suggested that your total protein intake should be about 10-25% of your daily caloric intake. If you aim to lose weight, you can raise that percentage to 15-35%. For example, in a 2000 kcal daily diet, this would be about 125 to 175 grams a day. That is about 50 grams per meal. This means, about 200-250 grams (about 7-9 oz of say, turkey breast) of meat, fish, or eggs in total.

Another way to calculate this: the maximum amount of protein should not exceed 2.2-2.5 grams per kilogram of bodyweight (i.e. if you are 70kg, then 70kg x 2.5 = 175 grams a day).

We know that the consumption of these daily amounts is completely healthy, which we will review below. In addition, given the satiating power of this macronutrient, it is very difficult to comfortably and regularly eat more than these amounts. (study)

Protein intake controversies

  1. Eating too much protein damages the kidneys: this is a common mistake made by interpreting results incorrectly. Several studies have shown that a high protein diet in patients suffering from kidney failure can be harmful. A decrease in protein intake during the day has a slight improvement in the markers of renal failure, compared to those who consume a lot of protein (study). From this data, many people have concluded that protein intake is harmful to the kidneys, but this is a fallacy. You can’t extrapolate results from one demographic (people with kidney failure) to another (generally healthy people). It would be like observing if it snows and it’s cold, then reasoning, if it does not snow it is not cold. In fact, multiple studies have shown that a healthy high-protein diet does not affect kidney health study. In short, avoid consuming more than 1.5 grams of protein per kilogram of weight if you suffer from kidney failure. If you’re healthy you can consume up 2.5g per kilogram of weight.
  2. Eating too much protein is carcinogenic:   As we discussed in this post, observational studies are sometimes misinterpreted.  Correlation is not causation, it is impossible to isolate a variable in real life…and especially when thinking about how much protein is too much. We must consider the quality of the meat (eating a hot dog is not the same as eating lean organic beef), the health of the population (do they exercise, are they smokers?), or the toxicity of the environment that they live in (pollution, run-off, pesticides and other factors). We will not deny that correlation exists and is powerful. For what it’s worth, if you decide on a high-protein diet, we recommend the following:

Recommendations for a high protein diet

Eat grass-fed, unprocessed meat: grass-fed meat contains conjugated linoleic acid (CLA), a type of healthy fat with anticarcinogenic effects. Furthermore, this type of meat tends to contain naturally high amount of antioxidants that protect fat oxidation. Some antioxidants, such as lutein, are associated with a lower risk of colon cancer in humans and have actively demonstrated the ability to reduce colon cancer in studies done on animals.

Vary your protein source: Don’t just eat red meat. For most of our history as human beings, we’ve had much more access to small animals such as fish, birds and rabbits than we’ve had to large mammals. Yes friends, hunting a mammoth was a real party. A hard, brutal, hard-work party.

Vary the part of the animal you eat: An interesting hypothesis, which has been discussed lately, is the ability of certain amino acids to raise levels of IGF-1 (a growth factor associated with increased risk of cancer) over others. Among the amino acids with the capacity to raise levels of IGF-1, methionine is the principal. Several animal studies have shown that methionine restriction decreased IGF-1 levels and improves life expectancy. It seems if we supplemented glycine in these animals, we would obtain the same effect as restricting methionine. Methionine is found mainly in the muscle while glycine is mainly in the viscera (organs like liver or stomach).

It makes sense that our physiology is not adapted to discard a part of the animal as nutritious as tripe, therefore, consuming only the muscle of the animal can lead to different imbalances.

Conclusions about protein intake

  1. A protein intake of up to 30% of total calories in an healthy foods has a satiating effect and provides essential nutrients.
  2. It is important to eat quality food, avoid processed ones, and vary both the type of protein as well as the part of the animal we eat.
  3. If you suffer from kidney failure, moderate your protein intake to a percentage between 0.8 and 1.2 grams per kg, or according to your doctor’s instructions.
  4. Remember, to eat an animal, you must first hunt it ;). If you hunt like an ant, you’ll eat ants. If you hunt like a Cro-Magnon, you’ll eat mammoths.

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