More A to Z Diet Trial Data

Readers may recall that last year, in March 2007, a study was published from a dietary trial comparing four dietary approaches for weight loss: Atkins, Ornish, LEARN and Zone - the A to Z Weight Loss Study.

Many reading through the findings cried foul - those in the Ornish group hadn't reduced their fat sufficiently, those in the Atkins group consumed more carbohydrate than recommended, and so on.

In my blog post I noted "...this study failed to achieve compliance out of the gate!"

I also noted that "We have before us is a study that really does indicate carbohydrate restriction can work well over a period of one year. Without sub-group analysis to evaluate results tied to compliance (hey, some of the participants had to be doing the various diet right, dontcha think?) we can't know just how effective doing Atkins or any of the diets is with good compliance though since the researchers didn't take their data to that level of analysis in this paper."

Ask and ye shall have an answer!

A follow-up paper was published in the International Journal of Obesity - Dietary Adherance and Weight Loss Success Among Overweight Women: Results from A to Z Weight Loss Study.

As the researchers note in the background of their abstract: "Dietary adherence has been implicated as an important factor in the success of dieting strategies; however, studies assessing and investigating its association with weight loss success are scarce."

Their objective?

"We aimed to document the level of dietary adherence using measured diet data and to examine its association with weight loss success."

And so they performed a secondary analysis on the data from the trial and lo' and behold, those who closely adhered to the dietary recommendations of their assigned diets were found to have greater weight loss when compared with those less compliant with their dietary recommendations.

The researchers found that "within each diet group, adherence to score was significantly correlated with 12-month weight change."

Atkins rs= 0.42 p=0.0003
Zone rs= 0.34 p=0.009
Ornish rs= 0.38 p=0.004

When comparing the highest level of compliance with the lowest the researchers noted significant differences in weight loss in the Atkins group!

Atkins
Highest compliance = 8.3kg
Lowest compliance = 1.9kg
p = 0.0006

Zone
Highest compliance = 3.7kg
Lowest compliance = 0.4kg
p = 0.12

Ornish
Highest compliance = 6.5kg
Lowest compliance = 1.7kg
p = 0.06

The researchers concluded, "Regardless of assigned diet groups, 12-month weight change was greater in the most adherent compared to the least adherent tertiles. These results suggest that strategies to increase adherence may deserve more emphasis than the specific macronutrient composition of the weight loss diet itself in supporting successful weight loss."