Look AHEAD at eight years: how much weight stayed off?

Why this study matters

Losing weight is one thing. Keeping it off for years is another. This report from the Look AHEAD (Action for Health in Diabetes) trial is one of the longest looks at what happens with a behavioural weight-loss program that continues over many years. For Canadian readers weighing lifestyle programs, medicines, or both, it offers a realistic picture of long-term results without any medicine.

Who was in the study

The trial enrolled 5,145 adults with type 2 diabetes and overweight or obesity. They were randomly assigned to one of two groups. The trial's intervention phase was halted in September 2012, but every participant had the chance to complete eight years first. At least 88% of both groups completed the eight-year assessment. The published summary does not state which countries took part.

What the researchers did

This was a randomized controlled trial. Randomized means chance decided which group each person joined, so the groups were alike at the start.

The intensive lifestyle intervention group received comprehensive behavioural weight-loss counselling over the full eight years. The diabetes support and education group received periodic group education only. This second group was the usual-care comparison. No weight-loss medicine was part of either program.

The researchers tracked weight each year. They also asked participants about weight-control habits, such as the ones people use to manage eating and activity.

What they found

At year eight, the intensive lifestyle group had lost an average of 4.7% of their starting weight. The diabetes support and education group had lost 2.1% (R32-C90). The paper reports this difference as statistically significant, meaning it was unlikely to be due to chance. The summary does not give a confidence interval, which is the range within which the true difference would likely fall.

Across the eight years, people in the lifestyle group reported practising more of several key weight-control behaviours than the comparison group. Within the lifestyle group, these same behaviours separated people who lost 10% or more and kept it off from people who lost weight but regained it. This last comparison is not randomized, because people chose their own habits, so it shows a link rather than proof of cause.

Side effects and people who stopped

The published summary we reviewed does not report side effects. It states that at least 88% of both groups completed the eight-year assessment, but it does not give a separate figure for how many left the program.

What this study does not tell you

• The lifestyle program ran for the full eight years. Results after a shorter program, or after support ends, may differ.
• The link between weight-control habits and keeping weight off is an observation, not a randomized comparison.
• This report covers weight only. The trial's main goal, fewer heart attacks and strokes, is not addressed on this page.
• Everyone in the trial had type 2 diabetes. Results may differ for people without diabetes.
• These percentages cannot be compared with medicine trials, which used different people, time frames and comparison groups.
• The summary we reviewed does not state who funded the study.

What it means in Canada

This report gives a long-term benchmark for what a continuing, high-contact lifestyle program achieved in adults with type 2 diabetes. It involved no medicine. Readers interested in how medicines fit alongside lifestyle care can read about semaglutide in Canada and tirzepatide in Canada. For provincial coverage questions, see public drug coverage by province. To find lifestyle and diabetes programs near you, see compare services.

Related reading

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

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