Wednesday, January 04, 2006

JAMA Publishes Findings of Seven Year Low-Fat Diet Study

Overall, this large randomized trial demonstrates that dietary recommendations for reducing fat and replacing it with vegetables, fruits, and grains do not increase body weight, which implies that guidelines that restrict fat intake and advocate increases in complex carbohydrates have not been a contributing factor to the weight gain that has been occurring in the United States throughout the past several decades.

The above paragraph comes from the JAMA article, Low-Fat Dietary Pattern and Weight Change Over 7 Years, that the press is all over today. I briefly wrote about the study in question last night and today include the full-text link so you can read it for yourself.

It isn't often that a prestigious medical journal like JAMA makes the full-text available to anyone - such widespread availability is typically reserved for research findings of great importance for public health.

So why this one?

With the popularity of low-carb diets and research findings supporting the efficacy of low-carb diets, the last five years have been a challenge for those staunch in their conviction that a low-fat diet is optimal for population-wide recommendation. This study was over a long period of time - seven-and-a-half years - and anticipated to be a definitive landmark highlighting the efficacy of low-fat diets.

This study was anticipated to be the "I told you so" finding many were hoping for, and even though the results are less than impressive, that isn't stopping the hype to convince you that this study had strong results that support the claims of those promoting low-fat diets.

Massaging findings is never a good thing - especially when it's patently obvious, and there, staring you in the face in black and white. In this particular publication, the glaring problem is found in the above statement "...guidelines that restrict fat intake and advocate increases in complex carbohydrates have not been a contributing factor to the weight gain that has been occurring in the United States throughout the past several decades."

The women across this study - from both groups - reduced the amount of carbohydrate in their diet (go look, it's in the data...better yet, look at the table that summarizes the data!)

Both groups, in fact, specifically reduced the number of grain servings they consumed each day. While the intervention group did indeed increase the number of servings of vegetables and fruits, this is not an increase in carbohydrate consumed because both groups decreased their calorie intake.

So, the net gram intake from carbohydrate actually decreased for both groups! But, that didn't stop the researchers from trying to pull one over your eyes - they state the intervention group increased carbohydrate. They didn't - it's in the data and there is no way around it.

An even closer look at the results find something odd - over the seven years, even with the calorie restriction of both groups, neither had an appreciable weight loss. More startling, both groups experienced an increase in their waist hip ratio (WHR) due to an increase in the size of their waistline - a measure we now understand is important in assessing health risks.

Why did these women experience an increase in their waistlines, over seven years, while eating a diet that had fewer calories than at the start?

Remember, both groups ate fewer calories at the end of the study than they did at the start - and both groups experienced a similar increases in waistline and WHR. What happened here?

It's also interesting that while both groups started the study consuming similar calories, the intervention group decreased their calorie intake by more than the control group over the seven years. Yet, the intervention group had no appreciable weight loss after the seven years of greater calorie restriction.

Just how many calories are we talking about?

From the data we learn that both the intervention group and the control group consumed similar calories daily at the start - intervention group ate 1788.1 calories a day (mean) and the control group ate 1789.1 calories a day (mean). To keep the math simple, let's call it 1790-calories a day at the start.

At the follow up, calorie intake between the two groups was markedly different. The intervention group was consuming 1445.9-calories a day and the control group was consuming 1564.0-calories a day. By my math, that's 118.1-calories a day LESS in the intervention group.

If the calorie theory is correct, as so many insist it is, the intervention group should have experienced an appreciable, significant weight loss compared with the control group. They didn't! They ate less calories and remained a similar weight compared to the control group even with less calories.

More alarming though is the increase in waistline and WHR in the intervention group - the reduction of calories did nothing to stop fat accumulation in the waistline!

But the press is working hard to convince you that this study is somehow proof that a low-fat diet is healthy!

Don't fall for it! These women decreased calories, lost no weight and experienced an increase in their waistline and WHR - they increased their risk for heart disease!

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