High-Protein Diet, do you know all its benefits?

High-Protein Diet, do you know all its benefits?

Let’s see what are the effects of a High-Protein Diet

Do you know what is the most important macronutrient? Yes, that is right, protein stands out among the other two macronutrients available in the body: fat and carbohydrates.

Benefits of a High-Protein Diet

Some of the effects of a high-protein diet are:

  • Promoting a feeling of satiety1
  • Increasing our calorie expenditure while resting2
  • Protecting the muscle mass and even losing more body fat3

Meat, eggs

With all these properties, it is no surprise that protein is currently the most popular product in current nutrition. In fact, some diets like the Atkins shook the very foundations of dietetics.

Do you want to lose body fat? Choose from the most popular options: ketogenic diet for athletes, Atkins diet or protocols such as the Pulse Feast by Christian Thibaudeau, etc.

Not eating carbohydrates at all will never be healthy, this should be clear. Some foods like vegetables or fruit are indispensable for the body. However, we should not see low-carb diets as harmful.

Risks of High-Protein Diets

Is this type of diet healthy? Some health professionals claim that it can be dangerous for our health, since there are organs such as the kidneys or liver that will have to “work more than usual”.

We talked about this topic in another article and we said that diets that are high in refined sugars caused more kidney problems that protein. In fact, protein could even have positive effects when it came to lowering the blood pressure.

Interestingly enough, the scientific evidence has not been able to prove how high-protein diets can be harmful for healthy people.

The issue is that when we try to validate or reject this type of hypothesis, we would actually need studies of 20-30 years. However, the results would only be a product of correlation-causality due to the huge number of factors that are involved. For example, genetics, sedentarism, calorie intake or medication, to name a few.

Study about High-Protein Diets

Some time ago, the team of Jose Antonio published a study. For those who do not know, Jose Antonio has become a worldwide referent due to his multiple studies in high-protein diets.

This time, the objective was to assess the effects of a high protein diet (+3g of protein/Kg body weight) for 8 weeks

Quite impressive, since the RDA (Recommended Dietary Allowance) of protein according to official organizations is 0.8g/Kg body weight. Therefore, we would be talking about a protein intake that is 4 times higher than the standard dose.


They selected 12 trained people who were divided in two different groups: Group A would take a normal protein intake and Group B would take the 3g protein/Kg body weight. After 8 weeks following this methodology, the groups changed.

8th Week group A group B

  • They used the self-reporting method with a mobile app (MyFitnessPal). Nevertheless, the self-reporting methodology is not very precise, since people tend to reduce or even omit some foods.
  • Moreover, they did physical tests at a 1RM (repetition maximum) and others at 60% of the 1RM in bench press with 5 attempts. This was done in order to see how both diets affected the performance.


When we compare the calorie intake from both groups, those who followed a high protein diet took 400Kcals more than the group that had a normal protein intake. But, what happened with the body fat?

Fat changes

If we look at this image, we will be able to see that many of those who changed from a normal to a high protein diet lost body fat

They also found out that those that had more fat-free mass were not really affected by this:

Fat-free mass

Regarding the performance, there were no differences between a diet or the diet. Therefore, the theory that a high-protein diet may hinder the performance was not reflected in this study. Nevertheless, it would be interesting to see the effect of a high workload in order to assess the importance of glycogen for the performance.

Body composition and performanceThere were no significant differences regarding the 1RM and 60% 1RM marks

And what about our health?

To sum up, there were not harmful effects caused by taking 3g protein/Kg body weight. After comparing both analytics, these were the results:


Let’s talk about some of the most interesting factors:

  • BUN (Blood Urea Nitrogen), which is the amount of urea that our kidneys need to filter. When our kidneys fail or do not work properly they filter less urea. Consequently, its blood levels increase. As you can see in the previous image, the group that took more protein did not have higher levels.
  • eGFR (Epidermal growth factor receptor). This parameter tells us how our kidneys work and if there is some kind of damage that alters their function. Those who followed a high protein diet had 101ml/min, which is a good value.GFR stages
  • Calcium: Even though this parameter does not have a significant relation to the kidneys, we want to comment on it because many experts argue that high-protein diets acidify the organism. Consequently, they would increase the calcium excretion and lower its levels. However, there was no such alteration in this study. Therefore, it proved that the calcium homeostasis is regulated by other factors such as calcitonin or vitamin D among others.
  • Bilirubin, alkaline phosphatase and transaminases: We have gathered all these parameters in a single group since they all have something in common: the liver.

If we analyze the information, we will notice that they did not suffer any changes after increasing the protein intake. Therefore, the liver still functioned properly.

Conclusions of the Study

We should not draw preliminary conclusions according to just one study. In fact, we would need several studies to support or discard a theory. In this case, the evidence that high-protein diets are not harmful is becoming strong.

Then, what is the issue? The duration of the studies.

Many of the negative effects of a diet are not visible until 20-30 years later. This is due to the fact that the deterioration of an organ does not necessarily have to be acute. To illustrate this point, if we do a study about how sugar affects our health in two weeks, the changes will probably be modest, right?

Does this mean that these people will not become obese if they keep that habit for 20 years straight? Obviously, the answer is no, since they will most certainly become obese.

Perhaps, the main issue is that we would need years and years in order to see the effects of a macronutrient. Moreover, we would also have to remove external factors that can affect the result (such as sedentarism, tobacco, alcohol, etc).

That is why we should avoid claiming that proteins are harmful or that they are more damaging that refined sugar.

Physical Exercise and Protein Intake

However, some of us may find high transaminase levels in our blood tests after doing intense physical exercise and increasing the protein intake.

Does this mean that your liver is damaged?

NO, it only means that we are destroying tissue (muscle) due to the stress caused by a strong muscle contraction. In fact, sometimes we may find strange cases of brown urine due to rhabdomyolysis or muscle tissue necrosis.

Do you want to make sure? Stop doing exercise for a week and take another blood test. If the values are back to normal you will know why.

If you want to learn more about High-Protein Diets and how they can alter the resultsof a blood test, click here here

What are the Effects of a High-Protein Diet?

More Adherence to the Diet

Increasing the amount of protein-rich foods will increase our chances of succeeding with this diet.

The key? Eat eggs, yogurts, cheese, meat, fish… That way, your daily diet will be more varied and it will look less like a “strict diet”. Moreover, you should forget that there is a connection between eating eggs or cheese and a cholesterol increase.

Healthy diet

In this sense, you should know that protein reduces the levels of ghrelin. But, what is that? It is the hormone that stimulates our appetite. This will help you lose fat more easily.

Better Blood Pressure

Some studies4,5,6 have proven that there is an inverse relation between the protein intake and the blood pressure. Consequently, its intake could prevent hypertension.

Improving the Cholesterol Levels

Cholesterol, triglycerides, HDL

Increasing the protein/carbohydrate ratio will help to improve the dyslipidemia and improve the lipid profile7.

Moreover, some of the studies (Lacroix M et a., 2004) show that following a hyperprotein diet for several months lowers the total cholesterol, LDL cholesterol and triglycerides.

On the other hand, a recent meta-analysis: Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis. Schwingshackl L1, Hoffmann G. Nutr J. 2013 Apr 15;12:48 shows how high-protein diets do not have significant effects on the total cholesterol, LDL, HDL, triglycerides and other biochemical parameters. Consequently, said diets do not have neither beneficial nor harmful effects on obesity or cardiovascular disease markers.

On the other hand, it could be interesting to see the results of a study carried out by: V.A. Aparicio et al. “Strength training reduces the metabolic acidosis and hepatic hypertrophy due to high-protein diet in rats”. According to this study, strength training considerably reduced the cholesterol and triglyceride levels. This effect was higher in the HP diet group.

Preventing Diabetes

Increasing the protein intake can lower the blood glycemia, increasing the insulin release. Some proteins, such as some types of WHEY, have been able to improve the glucose absorption by the muscle, reducing the insulin resistance.

The result of this will lower the chances of suffering diabetes

Protein Requirements

Do you know how much protein do you need? You should take into account that this varies depending on your activity and age. Who will need more? Those who do strength exercises.

Protein requirements for the general public

What is the recommended dose? Around 0.8 grams of protein per kilo of body weight a day, as long as they are proteins with a high biological value.

However, some studies and meta-analyses show that this amount is under what our body actually needs, both in young people and the elderly8,9.

What about athletes?

Are you an athlete? Then, you will need more protein than sedentary people. We suggest:

  • 1.2 and 1.6 g/day per Kg of weight in women
  • 1.3 to 1.8 g/day per Kg of weight in men
Athletes who follow a hypocaloric diet should take between 1.8 and 2.4g/day per kg of body weight in order to avoid losing muscle mass.


The benefits of a high-protein diet do not mean that you can eat whatever you want.

There are not clear benefits of following a diet over 2.5g/kg body weight.

We can see how increasing the protein intake over the general dose of 0.8g/kg body weight, can be good in terms of physical composition and health.

Protein-rich foods

Taking 3-4 times more protein than what is regarded as safe can entail some risks.

Stigmatizing an intake of 1.3-2g of protein per kg of body weight does not make sense in healthy people

In fact, that type of diets can even end up in muscle loss. This is clearly reflected in some studies like the one by Pasiakos, where 0.8-1.6g of protein/kg body weight were not enough to avoid muscle loss.

However, taking 3.5-4.5 of protein/Kg will not give you more benefits than a dose around 2.5g per kg of body weight.


Study 1-10

  1. Protein, weight management, and satiety. Douglas Paddon-Jones, Eric Westman, Richard D Mattes, Robert R Wolfe, Arne Astrup, and Margriet Westerterp-Plantenga.
  2. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review.Halton TL1, Hu FB.
  3. Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women.Manny Noakes, Jennifer B Keogh, Paul R Foster, and Peter M Clifton.
  4. Reed D, McGee D, Yano K, Hankin J: Diet, blood pressure, and multicollinearity.
  5. Dietary patterns in 10 groups and the relationship with blood pressure. Collaborative Study Group for Cardiovascular Diseases and Their Risk Factors. Zhou BF, Wu XG, Tao SQ, Yang J, Cao TX, Zheng RP, Tian XZ, Lu CQ, Miao HY, Ye FM, et al.
  6. Stamler JS, Caggiuala A, Grandist GA: Relationship of dietary variables to blood pressure (BP) findings of the Multiple Risk Factors Intervention Study (MRFIT).
  7. The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One-Year Follow-up of a Randomized Trial. Linda Stern, MD; Nayyar Iqbal, MD.
  8. Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. William M Rand, Peter L Pellett, and Vernon R Young.
  9. Protein requirements in the elderly. Volkert D1, Sieber CC.
  10. Plant Foods Have a Complete Amino Acid Composition. John McDougall, MD. a. Body composition and mortality risk in later life Wiklund P, Nordström P, Nordström (2012).

Study 11-17

  1. The prognostic value of body protein in patients with lung cancer. Kadar L1, Albertsson M, Areberg J, Landberg T, Mattsson S.
  2. Inverse regulation of protein turnover and amino acid transport in skeletal muscle of hypercatabolic patients.Biolo G1, Fleming RY, Maggi SP, Nguyen TT, Herndon DN, Wolfe RR.
  3. Responses in gut hormones and hunger to diets with either high protein or a mixture of protein plus free amino acids supplied under weight-loss conditions. Lobley GE1, Holtrop G2, Horgan GW2, Bremner DM1, Fyfe C1, Johnstone AM1
  4. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Johnstone AM1, Horgan GW, Murison SD, Bremner DM, Lobley GE.
  5. Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: comparison to hypocaloric high-carbohydrate diet. Piatti PM1, Monti F, Fermo I, Baruffaldi L, Nasser R, Santambrogio G, Librenti MC, Galli-Kienle M, Pontiroli AE, Pozza G.
  6. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. Pasiakos SM1, Cao JJ, Margolis LM, Sauter ER, Whigham LD, McClung JP, Rood JC, Carbone JW, Combs GF Jr, Young AJ.
  7. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. Halton TL1, Hu FB.

Related Entries

  • Read more about what would be the best type of protein for breakfast.
  • What about the best pre-workout protein?
  • You may be interested in finding out what is the best protein during the workout.
  • Learn more about the best post-workout protein.
  • And when it comes to sleeping, what is the best protein before bedtime?
High-Protein Diet Review

More adherence - 100%

Satiety - 100%

Fat loss - 100%

Better blood pressure - 100%

Better cholesterol - 100%

Diabetes prevention - 100%


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About Sergio Espinar
Sergio Espinar
Sergio Espinar is a sport nutritionist, specialized in fat loss and health in women. Coach, professor and speaker in the HSN Fitness School.
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