Tuesday, October 09, 2007

Spin time: nutrition research sponsored by National Pork Board

Women on a normal-protein no-meat diet lost weight at least as quickly as did women on a high-pork-protein diet, according to research that was funded, paradoxically, by the federal government's National Pork Board.

In the study, published in the February issue of the journal Obesity, 46 women were randomly assigned to either a normal protein diet with no meat or a high protein diet with above-normal amounts of pork protein. For both groups, the diet had very low amounts of total calories, 750 kcal per day below estimated energy needs for weight maintenance. [Update 11/18/2008: corrected statistic on calorie deficit].

The authors of the study were Heather J. Leidy, Nadine S. Carnell, Richard D. Mattes, and Wayne W. Campbell of Purdue University.

The women with normal-protein no-meat diets lost 9.5 kilograms of body weight in 12 weeks. Those with the high-pork-protein diet lost only 8.1 kilograms of body weight in the same period. The difference in weight loss was not statistically significant.

The new study corroborates a large body of research showing that drastic calorie-reduction diets of any flavor can show weight loss in a 12-week period, but such diets offer most women little hope for long-term weight loss.

For both groups of women in the study, most of weight loss was due to losing something other than lean body mass. Presumably, they lost fat or water mass. A much smaller amount of the weight loss was due to losing lean body mass. The normal protein no-meat group lost 2.8 kilograms of lean body mass (from 43.3 kg to 40.8 kg), while the high-pork-protein group lost 1.5 kilograms of lean body mass (from 43.0 kg to 41.5 kg).

How would you spin these results if you were the National Pork Board?

See the headline: "Checkoff-Funded Study with Lean Pork Reveals Protein’s Power to Preserve Lean Body Mass during Weight Loss."

It gets worse. The checkoff program's press release claims that women on the high-pork-protein diet "retained nearly double the amount of lean body mass." You might look at the numbers above -- showing lean body mass of 40.8 kg for the normal protein no-meat group and 41.5 kg for the high-pork-protein group -- and ask, in what sense did the latter group retain nearly double the amount of lean body mass? But you just lack the right amount of imagination: the high-pork-protein group retained nearly "double" the lean body mass, because its lean-body-mass loss of 1.5 kg is slightly more than half the loss of 2.8 kg for the normal protein no-meat group.

This nonsense just contributes to the public confusion. By supporting this type of scientifically empty public relations campaign, administered by the semi-governmental checkoff programs, the federal government tragically undermines its own respected research program in human nutrition.

4 comments:

Frank Castiglione said...

Wow. It's unbelievable these powerful groups manipulate information to sell their products. I always try to find out who contributed money or provided sponsorship when a new nutritional research is released to the public.

Iron-Man said...

Anyone would lose weight on a 750 calorie diet even if they were eating Snickers bars only.

Sonya said...

Actually, if you read the study, the diets were 750 calories per day BELOW their estimated weight-stable calorie intake (in other words, enough of a deficit to produce weight loss). Their ACTUAL average calorie intake was between 1500-1560 calories per day.

Parke Wilde said...

Thanks, Sonya. I corrected the statistic on the calorie deficit. The point of the sentence is still correct: all study arms were on a severe weight loss calorie restriction.