Tuesday, January 03, 2006

Seven Year Study of Low-Fat, High-Carbohydrate Diet

The Miami Herald article, Study examines Low-fat, high-carb diet, opens with the following sentence: Older women who ate less fat and more carbohydrates lost about 2 pounds over seven years, a large study showed.

Too bad it's not true.

Too bad Carla Johnson, the author of the above article, didn't bother to read the full text of the published JAMA article to know it's not true!

After receiving a head's up about the soon-to-be released study, I decided to read through the full article I was provided in advance to see what the fuss was all about. Saying I was underwhelmed by the actual data is a fair statement.

So, what was this study all about anyway?

Well, it followed more than 48,000 women (post-menopausal) for a little more than seven years, with the women randomized into two groups - Group 1, made up of 19,541 women, was the "intervention group" that was provided with specific instruction, group and individual sessions to promote a decrease in fat intake and increases in vegetable, fruit, and grain consumption without weight loss or caloric restriction goals; Group 2. made up of 29,294 women, was the "control group" that received only diet-related education materials with no instruction about changing their diet.

Each participant was evaluated at the start for "baseline" numbers about participants of each group.

The following is the mean "baseline" data:
  • Intervention and Control group BMI = 29.0
    Basically, on average, both groups were at the high end of overweight classification for BMI
  • Body weight = 76.8kg for the intervention group; 76.7kg for the control group
  • Daily Calorie Consumption
    Intervention = 1788.1/day; Control = 1789.2/day

    Both groups apparently ate slightly less calories each day than the average female in the United States, which is estimated as 1877/day (CDC Data)
  • Percentage of Calories from Fat = 38.8%
    This works out to an average of 77g of fat for the intervention group and 77.1g for the control group
  • Percentage of Calories from Carbohydrate = 44.5%
    This works out to an average of 198.9g of carbs for the intervention group and 199g for the control group
  • Percentage of Calories from Protein = 16.7%
    This works out to an average of 74.65g of protein for the intervention group and 74.69g for the control group

So, there we have the data at the start. Now let's take a look at the data from the follow-up:

  • Intervention group BMI = 29.0...Control Group BMI = 29.2
  • Body weight = 75.7kg for the intervention group...76.1kg for the control group
  • Daily Calorie Consumption = Intervention = 1445.9/day; Control = 1564.0/day
  • Percentage of Calories from Fat = 29.8% intervention group...38.1% control group
  • Percentage of Calories from Carbohydrate = 52.7% intervention group...44.7% control group
  • Percentage of Calories from Protein = 17.5% for both groups

This is what the press release for this study states: “In summary, the results of this long-term trial of diverse postmenopausal women demonstrate that long-term recommendations to achieve a diet lower in total and saturated fat with increased consumption of fruits, vegetables, and whole grains, and without focus on weight loss, do not cause weight gain.”

Are you kidding me?

These women REDUCED THEIR CALORIES - both groups! Not only that, they DID NOT increase carbohydrate consumption - in fact both groups actually DECREASED their intake of carbohydrates!

Look at the data again!

At baseline, the intervention group was consuming an average of 198.9g of carbohydrate each day - at the follow-up, they were eating just 190.45g!

Now who wants to tell me they "INCREASED" carbohydrates? Who do they think they're kidding here?

At baseline the control group was consuming an average of 199g of carbohydrate each day - at the follow-up, they were eating just 174.95g. Again, a reduction in carbohydrate intake!

Oh, that's right - the intervention group "increased" carbohydrate if we look at the percentage of calories. But, don't lose sight of the fact they DECREASED calories - so their "increase" is not an actual increase in carbohydrate intake, just fuzzy math using percentages of calories!

But, hey this reality didn't stop the lead author, Barbara V. Howard, from claiming her results "...will help people to understand that the weight gain we're seeing in this country is not caused by the lower-fat diets."

Come again?

What part of a calorie reduction of 322.2 calories a day did she miss?

If nothing else, this study should set off alarm bells that restricting calories to 1445.9-calories per day, down from 1788.1-calories per day, does nothing significant to reduce weight!

Can you imagine cutting your calories that much and seven years later your BMI is still at the upper end of overweight, bordering on obese?

They consider that success?

Not in my book. No thanks! I'll stick with controlled-carb and eat rich, nutrient-dense foods!

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