Friday, July 05, 2013

Exercise and Weight Reduction Fail to Save Lives in Diabetes Study

I hate having to tell people about pointless studies like the one just published in The New England Journal of Medicine by the nameless "Look AHEAD Research Group," but unfortunately, it's the kind of study that will have a lot of people saying "See this? Dieting and exercise won't make you live longer." (With the unspoken message: "So live it up. Have another Big Mac, light another Camel. When your time is up, your time is up.") In other words, people may leap to the wrong conclusion. So let's look at what was actually found.

The study followed two groups of obese type 2 diabetics (2,570 in the control group and 2,575 in the study group) for a median period of 9.6 years. The study group was subject to an "intensive intervention" of diet and exercise consisting of weekly group and individual counseling sessions for the first six months, sessions that occurred "with decreasing frequency over the course of the trial." Not surprisingly, subjects lost a modest amount of weight (just under ten kilos) in Year One, then gained much of the weight back, then lost some of the gainback toward the end of the study. But the control group also lost weight over the study period. By the end of the period, in fact, the control and study groups differed only 2.5% in weight. (The study group ended up at minus 6%; the control group, minus 3.5%.) Both started out with a body mass index of 36 (plus or minus 5.8 for the control group and 6.0 for the study group) and an average weight of 101 kg.

The major finding of the study was that the death rate among the two groups was not statistically different after 9.6 years. In the control group, 202 people died (57 from cardiovascular causes) while in the study group 174 died (52 cardio). In the words of the authors: "In conclusion, our study showed that an intensive lifestyle intervention did not reduce the risk of cardiovascular morbidity or mortality."

I have only two comments. One is that the study was not sized properly. The researchers admit they were banking on seeing an 18% difference between the two groups; and so they'd sized the study with that in mind. It seems clear to me that had they been more conservative and aimed for a higher enrollment target, the study's authors might very well have found statistically significant results. As it is, more people died in the control group. But the difference wasn't statistically significant.

A second way the study could have been improved would, of course, have been to get serious about weight loss. How can you call weekly meetings (for six months, in a study lasting ten years) an "intensive intervention"? How can you call 6% weight loss serious weight loss? When someone with a BMI of 36 who weighs 220 pounds loses 20, then gains some of it back, finishing the study at well over 200 pounds, that's not serious weight reduction, my friend. Not even close.

In "Cardiovascular Effects of Intensive Lifestyle Intervention in Type 2 Diabetes," New England Journal of Medicine, 24 June 2013, what we have are two groups of obese diabetics, each of which lost an unremarkable amount of weight and each of which suffered casualties at (surprise!) just about the same rate, over a ten-year period. That's not science, in my book. That's a waste of NIH grant money. But that's what passes for science in modern America.