poco tempo fa ho letto questo articolo su t-nation
Protein Will Not Make You Fat
T NATION | Protein Will Not Make You Fat
naturalmente non considero questo sito alla stregua di pubmed, anzi, ma lo studio citato è coerente con la mia personale esperienza
da medico non considero più di tanto le discussioni basate su considerazioni personali ma preferisco fare riferimenti a studi scientifici e\o alle evidenze date dai fatti, con tutti i limiti presenti in entrambi i casi.
copio-incollo il paragrafo relativo allo studio:
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Enter One of the Most Tightly Controlled Studies of our Time
In 2012, George Bray and colleagues (5) sought to examine whether the level of dietary protein affected body composition, weight gain, and/or energy expenditure in subjects randomized to one of three hypercaloric diets: low protein (5%), normal protein (15%), or high protein (25%).
Once randomized, subjects were admitted to a metabolic ward and were force fed 140% (+1,000kcals/day) of their maintenance calorie needs for 8 weeks straight. Protein intakes averaged ~47g (0.68g/kg) for the low protein group and 140g (1.79g/kg) and 230g (3.0g/kg) for the normal and high protein groups, respectively.
Carbohydrate was kept constant between the groups (41-42%), with dietary fat ranging from 33% in the high protein group to 44% and 52% in the normal and low protein groups, respectively. Lastly, during the course of the 8-week overfeeding period, subjects' body composition was measured bi-weekly using dual x-ray absorptiometry (DXA, the "gold standard" for measuring body composition).
Results
At the end of the study, all subjects gained weight with near identical increases in body fat between the three groups. (In actuality, the higher protein groups actually gained slightly less body fat than the lower protein group. This, however, wasn't significant).
The group eating the low protein diet gained the least amount of weight (3.16 kg) with the normal and high protein groups gaining about twice as much weight (6.05 and 6.51 kg, respectively).
As you can see, the additional ~3 kg of body weight gained in the higher protein groups (15% and 25%) was shown to be due to an increase in lean body mass and not body fat. To quote the conclusions of the authors:
"Calories alone contributed to the increase in body fat. In contrast, protein contributed to changes in lean body mass, but not to the increase in body fat."
While we can't say for sure the exact composition of the lean mass that was gained, we can assuredly say that the extra protein was not primarily used for fat storage. My hunch is that the protein was converted to glucose (via gluconeogenesis) and stored subsequently as glycogen along with some accompanying water weight. Either way, it wasn't body fat.
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Se siete daccordo potremmo analizzare questo studio o la bibliografia allegata all'articolo, o meglio ancora altri studi che affrontano il problema
cerchiamo però di non fare troppa filosofia perchè non ho una formazione classica
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