Really, you don’t need carbohydrates

I keep running across comments like this one, from “Ending the Food Fight,” by David Ludwig, MD, PhD: “[Low carb diets] do produce more weight loss than low-fat diets, but only temporarily.  After one year, people following both diets gain back nearly all of the weight they lose.  These approaches ultimately fail because our bodies and our minds rebel against severe restriction of any major nutrient, whether fat or carbohydrate.  (How long do you want to keep eating that bacon double cheeseburger, hold the bun, thank you?)”

First off, I assume Dr. Ludwig is referring to people who stop eating low carb and then gain back their weight, which of course, they will.   Continuing to eat low carb at the level of carbohydrates your body can handle, which might be 20, 50, or 100 grams a day, is one of the most successful ways to maintain weight loss.

Second, why does Dr. Ludwig assume that all macronutrients (fat, protein, carbohydrate) are equal, or equally required?  They’re not.  Carbohydrates in the form of agricultural grains did not even exist in the human diet until several thousand years ago.  People who eat a “Paleo/Primal” or “Caveman” diet eschew all grains, legumes, and dairy.  They eat mostly vegetables and meats, and a small amount of fruit.  (Modern fruit is larger, sweeter, and available for more of the year than ancient fruit).

It’s maybe not surprising then, given that they are so new, that carbohydrate is the only macronutrient your body does NOT require.  It can get along just fine on zero carbohydrate, unlike fat or protein.  “…animal foods contain all of the essential amino acids (the basic structural building blocks of proteins), and they do so in the ratios that maximize their utility to humans.* 94 They also contain twelve of the thirteen essential vitamins in large quantities…The thirteenth vitamin, vitamin C, ascorbic acid, has long been the point of contention. It is contained in animal foods in such small quantities that nutritionists have considered it insufficient and the question is whether this quantity is indeed sufficient for good health.”

Taubes, Gary (2007-09-25). Good Calories, Bad Calories (Kindle Locations 6551-6557). Random House, Inc.. Kindle Edition.

 It turns out that the tiny quantity of vitamin C in animal foods is sufficient, provided you aren’t eating a diet high in carbohydrate.  In other words, you only need to supplement the vitamin C available from animal foods if you eat a lot of non-animal foods.

Taubes, Gary (2007-09-25). Good Calories, Bad Calories (Kindle Location 6630). Random House, Inc.. Kindle Edition.

Another argument you sometimes hear is that dietary carbohydrates are required to provide glucose for the brain.  But this is not so.  The liver manufactures the fuel it needs from other nutrients if dietary carbohydrate falls below a certain level.

Taubes, Gary (2007-09-25). Good Calories, Bad Calories (Kindle Locations 6492-6498). Random House, Inc.. Kindle Edition.

And what about Dr. Ludwig’s opinion that people can’t live forever without the hamburger bun?  A great effect of a low carb eating plan is that the desire for carbohydrates greatly diminishes, or disappears altogether.  And in sensitive individuals, eating the bun after getting used to the low carb style will probably make you feel sick and tired.  Go ahead and try it once, like Juliana did with a scoop of ice cream, and you won’t be so tempted the next time.

Dr. Ludwig instead advocates a low-glycemic diet, which I bet works better than a low fat diet for many people.  But in sensitive individuals like Juliana it would not work because it includes more fruit and grains (even if they are whole grains!) than her system can handle.