You Ask, I Answer: Battle of the "Diets"

Andy, are you going to blog about [the study that concluded that a low-carb diet was more successful at helping subjects achieve weight loss and healthier blood cholesterol profiles than Mediterranean or low-fat ones]?

-- Anonymous
Via the blog

I was most certainly planning on commenting on this study, mainly because of some very distracting flaws I noticed.

Let's begin with some basic information.

The study -- partially funded by the Robert and Veronica Atkins foundation (potential bias, anyone?) -- took place over 2 years, during which 85% of the 322 participants stuck with their respectively assigned diets (low-fat, Mediterranean, and low-carb.)

Now with some of my "uh, wait a minute" impressions.

Firstly, when it came to weight loss, low-carb beat out low-fat by 4 pounds (10.3 lbs vs 6.3 lbs), but edged out a Mediterranean Diet (which includes higher carbohydrate consumption) only by 0.3 lbs.

And although the low-carb diet resulted in the best blood cholesterol profiles, it's important to note that for this study, researchers "urged [the] dieters [on the low-carb diet] to choose vegetarian sources of fat and protein."

In other words, although the low-carbers had the highest saturated fat intake out of the three groups, the majority of their fats came from plant sources.

There isn't anything groundbreaking here. Anyone keeping up with nutrition research knows that mono and polyunsaturated fats are recommended for heart health.

Hence, this study calls into question the belief so many low-carb fanatics like Gary Taubes fervently hold on to -- that saturated fat is the best for blood cholesterol levels.

The study specifically mentions that the blood cholesterol levels of the low-carbers is due largely to the consumption of monounsaturated fats.

Besides, I always wondered why low-carb enthusiasts even bother bragging about improved cholesterol profiles on their diets when, two seconds later, they turn around and say that the cholesterol-heart disease link is a lie and the result of "bad science." Which is it?

The study wasn't entirely a "low carb diets RULE!" piece, either.

For instance, the Mediterranean Diet -- which was highest in fiber -- proved to be the most effective at managing blood glucose levels.

Yet again, this goes against traditional low-carb beliefs (and, once again, those Gary Taubes loves to pontificate) that the research on fiber is "inconclusive at best" and that there is no need to have it in the diet.

Before anyone jumps down my throat about whether or not I read Good Calories, Bad Calories, Gary Taubes himself said at his New York University talk in March of this year that he didn't think high-fiber grains were any healthier than refined ones.

Speaking of fiber, I noticed that the low-fat group was only asked to consume "low-fat grains."

This struck me as odd, mainly because it is hard to find grains high in fat -- they are all low-fat.

Additionally, it's hard to overlook some bias.

The study does not urge low-fat dieters to consume the healthiest grains (whole grains), yet specifically requests that low-carb dieters eat the healthiest fats.

I also found it strange that for the majority of this study the low-carb group was consuming 120 grams of carbs a day. This is definitely higher than the much lower levels recommended by most low-carb advocates.

Atkins, for instance, usually calls for no more than 100 grams of carbohydrates per day during the maintenance phase.

Finally, take a look at the numbers and you see that although the low-carb group was not calorie-restricted, their caloric intake was lower compared to their pre-study diet.

So, as always, we are talking about weight loss as a result of reduced caloric intake.