Protein Diet for Weight Loss: Pros and Cons

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Louise Hay

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The protein diet for weight loss, better defined as HYPER-protein, is a diet based on the increase of dietary proteins.
The protein diet is NOT universally conceived: in fact there is no standard high-protein diet that is the same for everyone; for this reason, more than a separate dietary model, it could be considered a characteristic of the various nutritional regimes.

As anticipated, the protein diet is based on the increase (percentage or absolute) of dietary proteins, whether deriving from foods or from food supplements.
I believe it is now well established ... and in common agreement between professionals ... that, for the purpose of weight loss, it is essential:

  • Introduce less energy than that expense
  • Increase metabolism and improve the functionality of the organism with motor activity
  • Make the most of the interaction between energy nutrients and metabolism

Compared to all this, the protein diet for weight loss intervenes on several fronts:

  • It adequately supports the plastic needs of an organism in training
  • Significantly reduces glycemic and insulin peaks in the post-prandial period compared to a diet rich in refined carbohydrates (typical of overweight people)
  • It has an average specific dynamic action (ADS) superior to the traditional balanced diet
  • Promotes the onset of post-prandial satiety, thanks to the increased release of gastrointestinal hormones, such as cholecystokinin


On the other hand, the protein diet is NOT always to be considered the most suitable system for weight loss, quite the contrary! It is true that it represents a diet that is simple to manage and effective in reducing weight, but it is equally true that it has a number of negative aspects. These include:

  • High contribution of nitrogen groups to be disposed of; this determines a surplus of hepatic and renal work (bad characteristic for infants and the elderly, as well as for hypersensitive subjects or, even worse, for those suffering from disorders of the organs concerned)
  • Possible keto-acidosis, especially in conjunction with a drastic reduction in carbohydrates; this lowering of blood pH, in addition to determining a lower efficiency of the central nervous system, causes an increase in renal filtration, which is potentially dehydrating; NB. Ketone bodies are toxic to all tissues in the body
  • Possible worsening of the PRAL
  • Possible increase in saturated fatty acids and dietary cholesterol, with an increase in the risk of metabolic alterations
  • Possible insufficiency of glucose in sports performance which induces an increase in muscle catabolism; what does it mean, I say, to increase plastic nutrients ... if at the same time we foment tissue catabolism?
  • Possible insufficiency of dietary fiber
  • Possible gastric fatigue and digestive disorders
  • Possible alteration of the intestinal physiological bacterial flora

The wording "Possible .." at the beginning of each point described above depends on the technique with which the protein diet for weight loss is drawn up (whether with the percentage increase of proteins or with the absolute increase of the same) and from the respect or less than the rules for a healthy diet (in terms of consumption of fruit, vegetables, fish, water, red meat, simple sugars, frequency of meals, etc.).

Percentage increase in proteins

The PERCENTAGE increase of proteins in the protein diet for weight loss is very simple to apply; first of all we specify that, in order to lose weight, a diet should bring less energy than necessary, precisely 70% of the total energy requirement (e.g., in a NORMOcaloric diet of 2860kcal, 70% of the energy is equivalent to approximately a 2000kcal hypocaloric ).
To divide the low-calorie energy into the various energy nutrients it is essential:

  • Calculate 25% of the energy in lipids (e.g., in a diet of 2000kcal - 500kcal of lipids which is equal to 93g)
  • Calculate 1,0 or 1,5g of protein per kg of physiological weight (e.g., for a subject who should weigh 60kg - 60 or 90g of protein, which is equal to 240kcal or 360kcal)
  • Calculate carbohydrates from the remaining energy: subtracting both the energy of lipids and proteins from the 2000kcal (e.g. 2000kcal - 500kcal - 240kcal or 360kcal = 1260kcal or 1140kcal, which are equal to 336g or 304g of carbohydrates.

If we wanted to compare the nutritional balance of the NORMAL-calorie diet (therefore, before removing the energy necessary for weight loss) to that of the low-calorie diet (equal to 70% of the NORMAL calorie), we would observe that THE ONLY FRACTION OF NUTRIENTS THAT REMAINS QUANTITATIVELY EQUAL IS THAT PROTEIN, since it is calculated on the basis of the desirable physiological weight and NOT on energy. However, comparing the energy share of proteins to the overall energy, it can be seen that these take on a decidedly greater importance in the low calorie diet due to the PERCENTAGE increase of the same (e.g. 90g of proteins for the NORMOcaloric of 2860kcal represent 12,6 % of the energy, while 90g of proteins for the relative hypo-caloric of 2000kcal represent 18% of the energy).
Ultimately, the percentage increase in protein in the protein diet for weight loss (if you use the calculation method with protein coefficient * kg of physiological weight desirable) is INEXORBLE.

Absolute increase in protein

The absolute increase in protein in the protein diet for weight loss is not much more complex to understand, even if (in my opinion) it is less advisable because it is potentially unbalanced from a nutritional point of view; let's start by specifying that the absolute increase (also definable QUANTITATIVE) of proteins, ALWAYS corresponds to the percentage increase ... even if in much GREATER proportions!
The absolute or quantitative increase of proteins in the protein diet for weight loss, unlike the previous method, uses a protein coefficient * kg of physiological weight that is desirable GREATER than the NORMALcaloric (e.g., if the NORMOcalorica proteins equal to 2860kcal are calculated by a coefficient of 1,0g * kg of desirable physiological weight [eg, 1,0g * 60kg = 60g], in the protein low calorie diet for weight loss from 2000kcal with ABSOLUTE increase in proteins, these can be calculated by means of a coefficient of 2,0g * kg of desirable physiological weight [eg, 2,0g * 60kg = 120g].
Unlike the previous one, which keeps the protein weight constant in parallel with an energy reduction, this method INCREASES it quantitatively through the use of a GREATER * kg coefficient.

In summary:

  • Method of the protein diet for weight loss, low-calorie, with a percentage increase in proteins: e.g., 1,0g * 60kg = 60g out of a total of 2000kcal (18% of energy)
  • Protein diet method for weight loss, low calorie, with absolute or quantitative increase in proteins: eg 2,0gkg = 120g out of a total of 2000kcal (24% of energy).

Useful supplements

If the protein diet, while containing excess peptides, is fairly balanced in terms of recommended rations (vitamins and minerals), then no food supplement is necessary; otherwise, it is highly advisable to rely on your nutritionist or general practitioner in order to identify the right administration of specific supplements.

NB. Usually, nutrition is more than enough to cover the plastic needs of a protein diet for weight loss; on the other hand, for ease of use or to optimize food management, it might be useful to use food supplements such as: protein bars and whey, casein or soy protein powders.

Example of a high-protein diet for weight loss "

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