Protein and the Low Carb Dieter

Even the American Diabetes Association has seen that, to use the stilted language of one study:

… a joint committee of the American Diabetes Association, North American Society for the Study of Obesity and the American Society for Clinical Nutrition suggested that a low-carbohydrate diet may be preferred to a low-fat diet for the induction of weight loss and glycaemic control in subjects with type 2 diabetes.

That study, published in the Diabetes/Metabolism Research and Reviews journal in March, 2011, represents a bit of a turn-around for the ADA, which has long suggested a medium carb diet for type 2 diabetics.

How Much Protein?

There are concerns expressed, mostly by friends, that too much protein will cause kidney stones, impair liver function, contribute to bone loss, and cause other problems.

Historically, the recommended amount of protein has been expressed using a grams per kilogram ratio, with .66 to .8 grams of protein per kilogram of lean body mass total body weight. A man weighing 200 pounds weighs 91 kilograms, so the total protein recommended would fall into the 60 to 73 gram range. For a woman at 140 pounds (63 kg), the range is 42 to 50 grams. But it’s common to read recommendations on low carb forums that up to 150% of those levels is fine.

When I weighed 250 pounds, my minimum protein requirement according to The Protein Power Lifeplan was 120 grams per day, or about 1.1 grams per kilogram of weight. That’s a bit more than the .8 grams per kilogram recommendation. At .66 grams, the recommended protein level would be 75 grams. Expressed in terms of caloric content, 120 grams of protein represents 480 calories, or about 19% of a 2,500 calorie diet. (Note, the paragraph above was edited on April 3, 2011 to correct the numbers given in the Protein Power Lifeplan).

Dissenting Views

The Perfect Health Diet Blog advocates limiting protein to about 10% 15% of total caloric intake, a number very close to the .66 grams of protein per kilogram of weight. That blog post also has important information regarding protein maximums for pregnant women and children … a warning to those with “paleo babies” who, evidently, want to duplicate the insanity of vegan couples who starve their babies with inadequate diets, a problem that a Google search indicates happens every few years. (Babies are not just “little people”; they have unique nutritional needs. Nature itself provides a low 7% protein diet in breast milk).

Real Protein Requirements?

But, for non-pregnant, adult women and men, are the protein levels satisfactory? There is some evidence that we may have been wrong all along with the .66 to .8 gram of protein per kilogram of weight calculation.

In January, 2010, a study examined the method of determining the protein requirements of adults, and concluded that the proper amount of protein may be .93 to 1.2 grams per kilogram of body weight. Our 200 pound man is now expected to eat up to 109 grams of protein (17% of the caloric intake on a 2,500 calorie diet).

Problems with Protein?

But is that too much? What about our friend’s concern that our kidneys will produce stones, our livers will cease to function, and our bones will leech calcium and become brittle? A study published in December, 2010, in the Nutrition Journal concluded:

… protein-enriched meals replacements as compared to standard meal replacements recommended for weight management do not have adverse effects on routine measures of liver function, renal function or bone density at one year.

In this study, the subjects on the high protein diet consumed 2.2 grams per kilogram of LBM, more than twice the amount recommended on most low carb diet plans. It looks like the low carb forum participants may have been right all along; you can safely go 150% of the minimum protein requirements without too much concern.

But, there are caveats

These studies look at healthy, adult men and women, free of liver, kidney or other disease. Anyone with any chronic condition, or on any medication, should check with their doctor before adopting any diet.

And remember, children and pregnant or nursing women are unique and the same rules simply don’t apply.