Tag Archives: minimum protein requirements

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.

Protein Intake: Special Cases

In our Protein Requirements article we looked at the minimum protein requirement as stated in Protein Power Lifeplan and how that compared to new research in the optimum daily protein values. But there are “special cases” that should be remembered: children, pregnant women, and those with other health issues. Remember, general rules of thumb cannot take the place of your family doctor.

Do the minimum protein values in low carb diets put women and children at risk?

The Perfect Health Diet blog commented on this recently. They are a bit different from other low carb, paleo advocates:

At PerfectHealthDiet.com we’re advocates of protein restriction. We recommend:

  • Avoiding all protein-containing plants, as plant proteins tend to be toxic
  • Striving to eat fatty, not lean, meats and fish, in order to keep protein intake down and fat intake up

Protein restriction helps protect against viral and bacterial infections by promoting autophagy, the process of intracellular protein scavenging, digestion, and recycling. During autophagy, bacteria and viruses, as well as junk human proteins and damaged organelles, are digested. Autophagy has been strongly linked to longevity and is protective against many diseases.

Our advocacy of low protein intake separates us from many other Paleo bloggers.

Of special concern is a protein-rich diet for infants and children; Perfect Health Diet points out that breast milk contains just 7% of its calories in protein, showing, in their view, that we evolved for lower protein intake as infants and children (they also cite other research showing problems with protein levels that would be appropriate for adults, but harmful for children). Pregnant women should also be careful of eating too much protein. Perfect Health Diet quotes Dr. Loren Cordain:

[Y]ou probably should increase your fat and carbohydrate consumption, and limit protein to about 20-25% of energy, as higher protein intakes than this may prove to be deleterious to mother and fetus for a variety of physiological reasons….

“Protein intakes above this [25% of total calories] threshold may affect pregnancy outcome through decreased mass at birth and increased perinatal morbidity and mortality.”

The physiological basis for this aversion stems from a reduced rate of urea synthesis during pregnancy that is evident in early gestation as well as increases in the stress hormone cortisol. Hence, pregnant women should include more carbohydrate and fat (i.e. fattier meats) in their diets and limit dietary protein to no more than 20-25% of their total caloric intake.

Perfect Health Diet recommends an even lower level of protein for pregnant women, to just 10% of their total calorie intake.

So how do you calculate the protein allowance as part of your total caloric intake? To simplify things, remember that each gram of protein has 4 calories. In this example, we’re using a woman who maintains her weight on a 2,000 calorie diet when not pregnant; most authorities say she should add an additional 300 calories during her baby’s gestation.

For a woman eating 2,300 calories a day, 20% of calories is 460, or 115 grams of protein (460 calories divided by 4 calories per gram equals 115 grams of protein). For the lower level, 10% of calories is 230 or about 58 grams of protein.

So how does the low carb Protein Power diet match up in this case?

First, remember the warnings about starting any new diet during pregnancy; they are in every low carb book I have seen. You simply should not begin any diet that isn’t approved by your physician during pregnancy. (Even if not pregnant, you should always talk to your physician prior to starting any diet, just to make sure you don’t have a condition that could be aggravated by the new diet.)

But again, we find that Protein Power is not a “high protein” diet plan. The recommendations on low carb diets for non-pregnant adults fall within the ranges cited above. For a 5′ 8″ non-pregnant woman weighing 140 pounds, the Protein Power Lifeplan chart recommends 27 grams of protein per meal, for a total of 81 grams. That represents 324 calories out of the daily total, or about 16% of the total for a 2,000 calorie intake.

I am not convinced Perfect Health Diet is right about reducing protein levels below these levels, especially for healthy adults. Satiety, the feeling of satisfaction or of being satisfied after eating, is said by many low carb advocates to come from getting a good proportion of your calories from fat. But research also shows that primates will increase their food intake to obtain more protein if only low protein foods are available. If hunger is a problem, you will cheat on your diet and consume more food than you should. Adequate protein intake may help provide a measure of satiety as well.