Look AHEAD at four years: weight, fitness and heart risk factors

Why this study matters

Short programs often produce weight loss that fades. The bigger question for anyone living with type 2 diabetes is whether the benefits last. This report from the Look AHEAD (Action for Health in Diabetes) trial follows people for four years. It asks whether an intensive lifestyle program keeps weight off and keeps heart-related risk factors better than standard diabetes education. It does not report heart attacks or strokes, which were the trial's main goal.

Who was in the study

The trial enrolled 5,145 adults with type 2 diabetes and overweight or obesity. About 59.5% were women, and the average age was 58.7 years. The trial ran at many centres. More than 93% of participants provided outcome data at each yearly check. This report covers the first four years.

What the researchers did

This was a randomized controlled trial. Randomized means chance, not choice, decided which group each person joined. This keeps the groups similar at the start.

One group received an intensive lifestyle intervention aimed at weight loss through eating fewer calories and being more active. The other group received diabetes support and education, which served as the control group. A control group is the comparison used to judge whether the program made a difference. No weight-loss medicine was part of either program.

The researchers measured weight, treadmill fitness, HbA1c, blood pressure and blood fats every year. HbA1c is a blood test that reflects average blood sugar over about three months. The results below are averages across the four yearly visits, not the values at the end of year four alone.

What they found

The main finding is the average weight change across four years. The intensive lifestyle group had lost 6.15% of their starting weight on average. The diabetes support and education group had lost 0.88% (R32-C91). The paper reports the difference as statistically significant, which means it was unlikely to be due to chance. The summary does not report a confidence interval, which is the range the true difference would likely fall within.

Other results, averaged across four years:

The cholesterol and triglyceride results are reported in mg/dL, the unit used in United States laboratories. Canadian labs usually report these in mmol/L. We have not converted the numbers.

One result went the other way. LDL cholesterol (often called "bad" cholesterol) fell more in the comparison group (12.84 mg/dL) than in the lifestyle group (11.27 mg/dL). The paper explains that more people in the comparison group were started on cholesterol-lowering medicines.

At the four-year point itself, the lifestyle group still had greater improvements than the comparison group in weight, fitness, HbA1c, systolic blood pressure and HDL cholesterol.

Side effects and people who stopped

The published summary we reviewed does not report side effects. It also does not report how many people in each group stopped taking part, though it states that more than 93% provided data at each yearly visit.

What this study does not tell you

• The headline numbers are averages across four yearly visits. They are not the same as the result at the end of year four.
• Better risk factors do not prove fewer heart attacks or strokes. The trial's heart outcome report is not part of this page.
• The program involved a lot of contact and support. Lower-intensity programs may not produce the same results.
• The results cannot be compared directly with medicine trials. Different people, different comparison groups and different measurements were used.
• The summary we reviewed does not state who funded the study.

What it means in Canada

This report shows that a structured lifestyle program held onto a meaningful part of its early weight loss over four years for adults with type 2 diabetes. It does not involve any medicine. For information about how lifestyle programs sit alongside medicines, see semaglutide in Canada and tirzepatide in Canada. For what provincial plans cover, see public drug coverage by province. To find lifestyle and diabetes programs, see compare services.

Related reading

Other studies in this library that bear on the same question.

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