Diet Studies: What the Numbers Don't Tell You

This week I read a terrific article from last year by one of my favorite health journalists - Julia Belluz of www.vox.com.  She took a look at 4 dieters who were all participants in a study that compared a low-fat diet to a low-carb diet. Both diets produced pretty much the same results after a year - 11 pounds lost for low-fat dieters and 13 pounds lost for low-carb dieters. Those numbers are averages.

But averages are, of course, averages. What happens in a lot of weight loss studies is that some people do really well and lose a lot of weight. Others don't lose any weight at all or actually gain weight. And some are right there in the middle. So the average weight loss looks mediocre at best. But there are rich and instructive stories in each participant's experience that get lost in the averages. Why did the people who lost a lot of weight do so well? What kept the people who didn't lose weight, or even gained, from succeeding? Averages don't tell their stories. But Ms. Belluz takes a look at 2 people who succeeded - one on each diet. She did the same with 2 people who gained weight - one on each diet. She tells their stories here. Take a look:  

Why Do Dieters Succeed or Fail? 

What we see is where we fail as nutrition and diet experts. It's not just about the diet - it's about life. Our jobs, our environment, our families, our friends all have a big effect on our health and behaviors. Now, how do we design programs and studies that really help when all those factors are not helping? 

Beth Kitchin, PhD, RDN
Assistant Professor, Nutrition Sciences
University of Alabama at Birmingham