Low carb diets usually start with the proposition that you should eat a certain minimum amount of protein based on your lean body mass, no more than 30 – 40 grams of carbohydrate, and fill the rest of your diet with “good fats”. Protein Power includes a series of calculations to determine lean body mass, and then provides charts to determine your daily protein requirement. Protein Power Lifeplan simplified the process to include charts based on your height and weight.
The basic formula is about .6 of a gram of protein per pound of lean body mass (or, .6 gram of protein per .45 kg). For a person with a lean body mass of 150 pounds (67.5 kg), that’s 90 grams per day.
New dieters often express concern about the danger of “too much protein”, with kidney failure often a concern. A rule of thumb by dieters has been that up to 150% of your minimum protein requirement is no problem, and blood tests to measure kidney function in dieters exceeding their minimum protein requirement seems to bear this out.
Some people are alarmed at this, in part by the conservative Dietary Reference Intake levels of .66 to .8 grams of protein per kilogram of total weight. 150 pounds of lean body mass equals about 67.5 kg, and even at the higher recommendation of .8 grams of protein, that’s only 54 grams of protein. And yet low carbers routinely advise people that up to 135 grams … one and a half times the “minimum” requirement in Protein Power … is OK?
First, note that the Daily Reference Intake levels are for total body weight, not just lean body mass. Dieters want to “feed” their lean body mass so they don’t lose muscle along with fat, so they apply the calculation only to lean body mass, not total weight. So there is a built-in safety margin already in the low carb diets. And the fatter you are, the bigger the safety margin.
There’s also new evidence that protein requirements have been “significantly underestimated”, according to a new study released in the journal Current Opinion in Clinical Nutrition and Metabolic Care:
The mean and population-safe requirements in adult men were determined to be 0.93 and 1.2 g/kg/day and are 41 and 50%, respectively, higher than the current Dietary Reference Intakes recommendations.
To calculate the safe dietary intake of protein, researchers have been looking at “nitrogen balance“, using single linear regression analysis. The researchers re-examined this, applied two-phase linear regression analysis (considered more appropriate for “biological analysis of dose-response curves”), and came up with higher recommendations.
Considering the inherent problems associated with the nitrogen balance method, we developed an alternative method, the indicator amino acid oxidation technique, to determine protein requirements The mean and population-safe requirements in adult men were determined to be 0.93 and 1.2 g/kg/day and are 41 and 50%, respectively, higher than the current Dietary Reference Intakes recommendations.