Losing 5% of body weight and maintaining that loss for four years or more made no difference in strokes, heart attacks, or death rates for heavy people with Type 2 diabetes. So says the Look AHEAD trial, the biggest study ever done on “lifestyle intervention” for diabetes.
Look AHEAD (Action for Health in Diabetes) was a huge trial, involving 16 different treatment centers around the country. It started 11 years ago and enrolled 5,145 people aged 45–76. All had Type 2 diabetes and a BMI greater than 25.
Half the people (controls) were given a standard program of diabetes education, while the intervention group received intensive coaching and support aimed at weight loss. According to The New York Times, people in this group were put on a diet of 1200 to 1500 calories a day. Those who weighed more than 250 pounds were allowed 1500 to 1800 calories a day, a pretty tight restriction. The exercise program was at least 175 minutes a week of moderate exercise.
In 2010, researchers excitedly reported that the program was giving great benefits. People were losing weight, and their heart risk factors seemed to be going down, too. As Diane Fennell reported here,
On average, the lifestyle interventions group had greater improvements in weight, fitness, A1C, systolic blood pressure, diastolic blood pressure, HDL cholesterol, and triglycerides than the control group.
But the reduced risk factors didn’t translate into actual reduced risk. Now the National Institutes of Health have stopped the study because both groups were having the same rate of heart attacks, strokes, angina, and death. Those cardiovascular events were the main outcomes the study was analyzing, so the intervention “didn’t work.”
What Is Happening Here?
How can we explain these findings? I’m not surprised that weight loss didn’t help. It rarely does. People always gain the weight back, and weight doesn’t have that much to do with diabetes in the first place. Many thin people get diabetes, and most overweight people never do. So no big deal there.
But everyone thought that reducing glucose, blood pressure, and cholesterol would prevent heart disease. Everyone thought exercising would improve heart health. In fact, dozens of studies have proved that they do. So why was this time different? It’s hard to explain, especially since the full study data has not yet been released.
I have been suspicious of Look AHEAD all along, because the intervention group received way more attention than the control group. As Diane reported,
Lifestyle intervention … [was] reinforced with individual or group visits on a weekly basis for the first six months of the study, three times a month for the second six months, and at least twice a month for years two through four. The [control group] was given three group sessions a year that focused on diet, physical activity, and social support.
More support has health benefits of its own, so the study was heavily slanted to succeed. Some of the study’s lead investigators, such as study chair Rena Wing, PhD, have focused their entire career on weight loss.
And sure enough, Dr. Wing is reporting Look AHEAD as a success, because it “found that people who are obese and have Type 2 diabetes can lose weight and maintain their weight loss with a lifestyle intervention.”
This is a highly misleading claim. At year four, subjects had gained back roughly half of their relatively modest weight loss. For a 200 pound person, an 8% loss (average for the group) is 16 pounds, and half of that was regained.
The intervention was far more intense than anything people can do outside of a scientific study. In the real world, nobody is seeing health professionals every week for a year to lose weight.
And despite this intense support, they didn’t lose much, and the rates of cardiovascular problems and deaths were the same for both groups. Why?
It could be that study participants were a selected group whose hearts were in pretty good shape. Participants had to pass a prestudy treadmill test, and their blood pressure had to be at least moderately controlled (below 160/100). They were also motivated — they had to log their food intake for a couple of weeks just to get in the trial. So maybe they weren’t at that much risk in the first place.
Dr. Mary Evans of the National Institutes of Health said the positive news is that “both groups had a low number of cardiovascular events compared to previous studies of people with diabetes.”
Although the intervention did not reduce cardiovascular events, the intervention group had less sleep apnea, reduced their diabetes medications, had better physical mobility and quality of life. To me, those benefits are just as significant as heart attacks and strokes, especially since the death rates in both groups were low.
In fact, it’s interesting that this outcome is reported as a failure. Imagine a drug trial in which the drug reduced A1C, blood pressure, cholesterol, and sleep apnea, without affecting heart attacks and strokes one way or another. Would this be reported as a failure?
Please. That drug would become the newest treatment recommendation. Everyone would be prescribing it. But if it’s a “lifestyle intervention,” it’s a failure.
And note that weight loss advocates are spinning Look AHEAD as a success. Dr. Wing says it proves people can, too, keep weight off. Others are saying (spinning) that “lifestyle change doesn’t work, so take more drugs instead.”
My take is that probably the weight-loss focus led to people getting bad dietary advice. The study guidebook says,
The recommended diet is based on guidelines of the ADA and National Cholesterol Education program and includes a maximum of 30% of total calories from total fat, a maximum of 10% of total calories from saturated fat.
That means a lot of carbs, which most of us believe is bad for diabetes. Also, low-calorie diets can stress the body and may cause as many problems as they solve.
The fact is, we KNOW that exercising, eating better, and reducing stress work. We read about it here every week. I suggest we keep eating healthy, moving our bodies, and enjoying life, without counting pounds or calories (just carbs).