Did you hear? From the New York Times last week: Diabetes Study Ends Early With a Surprising Result. Thus far there's been some of the usual responses from the low carb community, and I expect more to come. For starters, the writer is Gina Kolata, a woman reviled by Gary Taubes and thus his adoring fans, so we'll get the usual round up of Gina doesn't get it that low carb is the bestest and only way to treat diabetes ... duh!! Let's look a bit closer, shall we?
First, keep in mind this study has not been published up, so we're dealing with press releases and quotes here. Secondly, ending the study early makes it sound quite a bit more dire than what we know to have happened. The study was apparently to last 13 years (odd duration, that), but was ended at 11 years because no differences were seen between the study and control groups over that time. Sounds prudent, because likely they looked at the numbers and probably concluded that there would need to be an unfathomable number of incidents/deaths in the remaining two years to alter the results. Save the money. Good.
Let's look at the study:
- 5,145 overweight or obese people with Type 2 diabetes, randomly assigned to intervention or general health counseling sessions.
- Intervention: Diet (12-1500 cal/day for those under 250 lbs, 15-1800 cal/day for those over 250 lbs) and Exercise (~ 3 hrs/week, moderate -- presumably aerobic -- exercise).
- Control: General health counseling
After 11 years, from the article:
... the intensive program did not help.... the two groups had nearly identical rates of heart attacks, strokes and cardiovascular deaths.
“I was surprised,” said Rena Wing, the study’s chairwoman and a professor of psychiatry and human behavior at Brown University’s medical school.
Like many, she had assumed diet and exercise would help, in part because short-term studies had found that those strategies lowered blood sugar levels, blood pressure and cholesterol levels.
OK, so my first question is this: How old were the participants? We're all aware of the statistics we're reminded of in the article, that diabetes roughly doubles (or a bit more) risk of CVD. But if they weren't following a population in which we see significant amounts of such events to begin with, it's no surprise to me when no difference is seen regardless of the intervention.
But assuming this was in a population in which we would expect to see enough events over a decade or so to see meaningful differences, let's look a bit further.
The study participants assigned to the intensive exercise and diet program did lose about 5 percent of their weight and managed to keep it off during the study. That was enough to reduce cardiovascular risk factors.
Since the diet prescriptions included a weight demarcation of 250 lbs, let's use that number as an "average" participant. Five percent of 250 is 12.5 lbs. So the average person assigned to the "rigorous intervention" went from obese to less obese at 237.5 lbs. Those who were less obese to begin with, say someone weighing 180 lbs to start lost a whopping average of 9 lbs. Perhaps this study can put an end to the "lowering the bar of expectations" practice of hyping the trade-offs from nominal changes in body weight. So these people are being congratulated for accomplishing very little.
I can hear it now, this just goes to show how useless ELMM is ... gotta go low carb!! Does anyone out there truly believe that if your average 250 lb person complied with a diet of 1500 cal/day for a decade would still weigh nearly as much? It sounds like this study included a diet phase early on (6 months perhaps?) during which the participants lost weight, and then maintained the losses. Did they continue the exercise? These are details I'd like to see when this study is eventually published up. How many are even following the "rigorous program" to any degree?
We know from countless short term studies that compliance varies greatly. Drop-out rates can be as high as 50% with 30% not being unusual. In the rather more rigorous Shai study, the six year followup offers further insights. In that study, the diets were partly administered for two years in a workplace environment. As I recall, the cafeteria had foods labeled as appropriate for the particular diet and/or with information readily available so participants could make easily informed choices. Presumably even if this labeling stopped, these participants could still recognize their foods improving the likelihood of compliance. We learn that under those conditions ~95% completed the 2 year study, but the adherence rate was only 85%. So was that 85% of the completers which would be roughly 80% of the initial group. They were able to follow up with 95% of those who completed at two years which translated to roughly 80% of the original participants, even if we presume 85% compliance amongst these, we're now down under 70% of the original participants under these rather more ideal conditions. Since all groups regained some weight, it's fair to say that compliance was likely nowhere near 85% at the six year point. So imagine what the compliance might be in this study we're talking about, a decade plus out?
I'd be surprised to learn that the current study was worth the investment at all. I'm thinking not. Here's another thought. Imagine you're an overweight/obese diabetic and have been recruited for a study and are assigned to the general health counseling group. No doubt you are further apprised of all the negative impacts out-of-control diabetes can have on your health. This "control" group didn't do nothing, they may well have undertaken lifestyle changes on their own. Perhaps they lost an average of 2% of their original weights. A control group instructed not to make lifestyle changes would be unethical, so this is not really a true control group after all.
In any case, and again we need to wait for the study publication to get some exacts on this, later in the article we learn:
... the results meant that people with diabetes might have a choice. The group assigned to diet and exercise ended up with about the same levels of cholesterol, blood pressure and blood sugar as those in the control group, but the dieters used fewer medications.
I'd say that's a good thing, no? So the dieters were able to achieve the same result with fewer medications. Isn't that what all the low carbers are after? Isn't that what most of those requiring medications are after? I'd think so.
You know what would be interesting? An analysis of this study data looking at change-in-weight vs. outcomes. If the average weight loss amongst dieters was 5%, no doubt some lost a lot more and others lost none or even gained weight. Also no doubt some of the control group undertook their own lifestyle changes (maybe even low carb!) during the ensuing decade. What I would hate to see is folks getting the take home message some of the low carbers (usual suspects folks, no need to link) are piling on along with the mainstream -- that diet and exercise are ineffective treatments for diabetes. I'm going to call bull and shit on that one.
A final note: Is anyone surprised by these (sketchy) results? I'm not. Lifestyle change is difficult ... most of us here oughta know. Short term studies are always promising for those who complete them and comply. While weight is not an ultimate determinant of health, excessive fat is simply not health improving for anyone. It's not necessarily detrimental to all, or equally detrimental for that matter, but it's unlikely to improve health (and note the word excessive, not a little extra). To me the take-away message (as of now) from this study is that lifestyle change with some medications can be equally effective as more medications. The low carbers who believe their lifestyle change is superior should seize on that and continue to promote low carb, but keep those Shai results in mind. On average ....