Saturday, August 27, 2005

Low-Carb: Two Studies - Different Findings

The media last week picked up the news that two studies investigating low-carb diets were completed and the results are in.

The first study from researchers at the University of Illinois found that diet composition rich in protein combined with exercise was more effective for weight loss than the USDA Food Guide Pyramid with both diets providing participants the same calories each day.

Both groups consumed the same number of calories, but the first group substituted high-quality protein foods, such as meats, dairy, eggs, and nuts, for foods high in carbohydrates, such as breads, rice, cereal, pasta, and potatoes.

The really important difference was the fact that when combined wiht exercise, the "high protein" group lost fat while sparing lean body mass and the USDA Food Guide Pyramid group lost muscle - as much as 25% to 30% of their weight loss - with their fat.

But, in the protein-rich, high-exercise group, Layman noted a statistically significant effect. That group lost even more weight, and almost 100 percent of the weight loss was fat, Layman said. In the high-carbohydrate, high-exercise group, as much as 25 to 30 percent of the weight lost was muscle.

In addition to the muscle-sparing effects, those following the higher protein diet also experienced greater improvements in their triglyerides and had a more dramatic (statistically significant) effect on trunk fat (in the mid-section). The researchers credit an increase in leucine in the higher protein, low carb approach as contributing to these effects.

As lead researcher, Donald Layman noted, "The diet works because the extra protein reduces muscle loss while the low-carbohydrate component gives you low insulin, allowing you to burn fat. We believe a diet based on the food guide pyramid actually does not provide enough leucine for adults to maintain healthy muscles. The average American diet contains 4 or 5 grams of leucine, but to get the metabolic effects we're seeing, you need 9 or 10 grams."

To achieve that leucine level, the researcher recommended adding dairy, meat, and eggs, all high-quality proteins, to the diet. According to Layman, losing weight doesn't have to mean relying on supplements to fill in nutritional gaps in your diet. "If you use a high-quality protein approach to your diet, you can actually improve the overall quality of your diet while losing weight," he said.

Now the above study was a four month investigation. That's considered "short-term" and researchers really prefer long-term data, which brings me to the second study in the media this week from down under.

Researchers from Otago University just completed a one-year study comparing conventional diets to Zone-type 40:30:30 diets to high protein, low-carb Atkins-tyle diets.

The new findings are a follow-up to the data released at six months where the researchers concluded that "In routine practice a reduced-carbohydrate, higher protein diet may be the most appropriate overall approach to reducing the risk of cardiovascular disease and type 2 diabetes."

As reported in New Zealand's Stuff, the researchers are now strongly advising against sticking to the restrictive diet for more than a year, because of its potentially harmful effects on the cardiovascular system and anti-oxidant levels.

Hmmm....I wonder, what changed their mind?

How about we go look at the data?

Oh, it's not yet published. But it will - soon - really - in the International Journal of Obesity!

So, we have no data to look at.

We have only a news article at this time to try to assess a research study and data.

Ya know what I call this? Convenient.

But, I digress....what the article does tell us is that the Atkins-type diets lost the most weight but gained more quickly when they abandon the strict rules. As one of the researchers, Dr Kirsten McAuley said, the change after the first six months is "[m]ainly because it was too restrictive, we would certainly have concerns about high-fat diets."

Throughout the article there is anecdotal experiences provided by some who followed the diets. Yet, there is no hard data offered. No data providing insight into cholesterol levels, bone density, weight loss, fat loss, muscle loss, glucose control - basically nothing considered hard data which is what we need here!

Based on what we do have available, it's already clear that part of the "problem" was dieters abandoning the low carb diet for another approach.

If weight gain happened after a switch to a different approach, an approach many consider "healthy and better" - one must ask - WHY! Why did the dieters success reverse on a different approach?

No one seems to be asking that question - instead we find the researchers stating that the problem was the low-carb diet, when the facts available (published data) show the approach worked.

Until the data is published it is difficult to write more about this study. What I will do is await the publication in the International Journal of Obesity and then report back to you my readers what the data reveals! Until then, I see no reason to abandon controlled-carb diets - the weight of the evidence, even with this potential study showing a negative result, still weighs in favor of controlled-carb nutritional approaches!


  1. Great post--I need to hear these things--gives me additional peace of mind knowing alot of things are interpreted incorrectly and with ulterior motives when it comes to speaking of low carb diets.
    It's tiring hearing the same rhetoric over and over.
    Very tiring.

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  4. Folks, I delete comments encouraging readers to go to sites soliciting MLM schemes or unrealted material. Please do not post links to unrelated material or commerical entreprises as they will be deleted!

  5. Anonymous3:22 AM

    I get frustrated with these studies because they virtually never say what kind of carbohydrates, i.e. refined, whole, fermented, etc.