Ho-hum. Another day, another study "proving" the dangers of a low carb diet. This new one comes out of Tufts University, and claims to show that a low carb diet impairs memory, while a low calorie diet does not.

Uh-huh. Let's dolly in for a closer look.

First of all, this was a very small study -- just 19 women, ranging in age from 22 to 55. They were allowed to choose either a low carb diet or a low calorie "balanced" diet. They split, with 9 women choosing low carb and 10 choosing low calorie.

Before they started their diets, the women were given tests that assessed attention, long-term and short-term memory, and visual attention, and spatial memory. They then went on their chosen diets, and were assessed twice again during the first week on their diet. During that week, the low carbers showed decreasing memory and slowed reaction time.

During the second week, carbs were added back to the low carbers' diet, and they were assessed twice more during the next two weeks. Their cognition skills "returned to normal."

Argh. Can you see how wrong-headed this study was? Because it jumped out at me with the first article I read about it.

They tested low carb dieters only during the first week of a low carb diet. Remember your first week of low carbing? Chances are that about three days in you were hitting the wall. Your body had run out of glycogen (stored sugar,) but hadn't yet made ketones in any great quantity, nor up-regulated the enzymes needed to burn fat for fuel, nor increased gluconeogenesis, the process by which your liver creates what little glucose you really need.

Clinical tests show that it takes roughly two weeks for a body to thoroughly adjust to carb restriction. So this study stopped half-way through the process, and then concluded that "low carb diets impair memory." Truth is, this study says nothing about cognitive function on a long-term low carb diet.

But there's more. The headlines are trumpeting "Low Carb Diet Impairs Memory," but even during that one week of a real low carb diet, the news was not all bad. The low carb dieters beat the low calorie dieters during the "attention vigilence task" -- ie, maintaining focus for extended periods. Dunno about you, but that's a pretty important ability in my life. Furthermore, the low calorie dieters suffered more confusion. So how does this study indicate that low carb diets are uniquely problematic?

Once again, we have a study that appears to have been deliberately designed and interpreted to fulfill the researchers' pre-existing prejudices about a low carb diet.

That's not science, folks. It's propaganda.