The main finding
In one sentence: In a 56-week trial of 3,731 adults without diabetes, daily liraglutide 3.0 mg (Saxenda, Victoza) plus lifestyle counselling led to a mean weight loss of 8.4 kg, compared with 2.8 kg for placebo plus counselling.
Group averages, not an individual prediction. A trial result describes what happened to a defined group over a defined time.
On this page
Why this study matters
Liraglutide was the first daily injectable medicine in the GLP-1 family to be studied at a 3.0 mg dose for weight management. SCALE Obesity and Prediabetes was the main trial behind that use. It answers a simple question: when added to diet and exercise advice, how much more weight do people lose with liraglutide than with a dummy injection? For a Canadian reader, this is the core evidence for a medicine that has been available for several years and is still prescribed.
Who was in the study
The trial enrolled 3,731 adults who did not have type 2 diabetes. They had a body mass index (BMI) of at least 30, or a BMI of at least 27 with high cholesterol or high blood pressure, treated or not. BMI is a number that compares weight with height.
At the start, the mean age was 45.1 years, the mean weight was 106.2 kg, and the mean BMI was 38.3. Most participants (78.5%) were women, and 61.2% had prediabetes, meaning blood sugar that is higher than normal but not high enough to be diabetes. The trial ran for 56 weeks.
What the researchers did
This was a randomized, double-blind trial. Randomized means chance decided who got which treatment. Double-blind means neither participants nor staff knew who was getting the medicine. Placebo is an injection that looks the same but contains no medicine.
People were assigned in a 2 to 1 ratio: 2,487 received liraglutide 3.0 mg by daily injection under the skin, and 1,244 received placebo. Both groups received counselling on lifestyle changes.
The trial had three main outcomes: the change in body weight, the share of people losing at least 5% of their starting weight, and the share losing more than 10%.
What they found
At week 56, people in the liraglutide group had lost a mean of 8.4 kg, and people in the placebo group had lost a mean of 2.8 kg (R32-C79). The difference was -5.6 kg, with a 95% confidence interval of -6.0 to -5.1. A confidence interval is the range in which the true difference most likely sits. Because the whole range is well below zero, the result is unlikely to be due to chance.
| Outcome at 56 weeks | Liraglutide 3.0 mg | Placebo |
|---|---|---|
| Mean weight lost | 8.4 kg | 2.8 kg |
| Lost at least 5% of starting weight | 63.2% | 27.1% |
| Lost more than 10% of starting weight | 33.1% | 10.6% |
The abstract also says liraglutide was associated with improved metabolic control, but the summary we reviewed does not give figures for that.
The analysis used a method called "last observation carried forward". If someone stopped coming to visits, their last recorded weight was treated as their final weight. This method can overstate benefit if many people dropped out.
Side effects and people who stopped
The most frequently reported side effects with liraglutide were mild or moderate nausea and diarrhea. Serious events occurred in 6.2% of the liraglutide group and 5.0% of the placebo group.
The published summary we reviewed does not report how many people stopped treatment in each group, or how many stopped because of side effects.
What this study does not tell you
- The trial lasted 56 weeks. It does not show what happens over several years, or what happens to weight after the medicine is stopped.
- The summary we reviewed does not report dropout numbers, and the analysis method may make results look better if dropouts were common.
- Everyone in the trial was free of type 2 diabetes. Results for people with diabetes were studied in a separate trial that is not covered here.
- Both groups got lifestyle counselling, so the result shows what liraglutide adds on top of that support, not what the medicine does alone.
- The trial did not compare liraglutide with other weight-management medicines. Results from different trials cannot be lined up against each other because the participants and methods differ.
- The trial was funded by the maker of liraglutide.
What it means in Canada
This page describes one trial and does not say whether liraglutide is right for anyone. To learn about the medicine itself, see liraglutide in Canada. Information on what provincial plans pay for is at public drug coverage by province, and compare services lists how different weight-management programs work.
Common questions
How much weight did people lose on liraglutide 3 mg in the SCALE trial?
After 56 weeks, people on liraglutide lost a mean of 8.4 kg and people on placebo lost 2.8 kg, a difference of 5.6 kg.
What share of people lost at least 5% of their weight with liraglutide?
63.2% of the liraglutide group lost at least 5% of their starting weight, compared with 27.1% of the placebo group.
What were the most common side effects of liraglutide in SCALE?
The most frequent side effects were mild or moderate nausea and diarrhea. Serious events occurred in 6.2% of the liraglutide group and 5.0% of the placebo group.
Related reading
Other studies in this library that bear on the same question.
SCALE Sleep Apnea: liraglutide for people with sleep apnea
Liraglutide in adolescents with obesity
S-LiTE: exercise, liraglutide, or both after diet weight loss
STEP 8: semaglutide versus liraglutide head to head
S-LiTE: one year after stopping liraglutide or exercise
Source
Original paper: Xavier Pi-Sunyer, SCALE Obesity and Prediabetes, The New England journal of medicine, 2015. PubMed: https://pubmed.ncbi.nlm.nih.gov/26132939/. DOI: https://doi.org/10.1056/NEJMoa1411892. Funding: The trial was funded by Novo Nordisk, the maker of liraglutide. How we summarized it: abstract and extracted data.
This page explains a published study. It is not medical advice and does not describe whether a medicine is right for you. Talk to your doctor, nurse practitioner or pharmacist about your own situation. Reviewed and signed by two pharmacists registered in British Columbia, 2026-09-18.
Evidence records behind this page
Each record is a row in the clinical evidence file, taken from the published paper named above. The caution column is the limit the researcher recorded for that number.
This table scrolls sideways.
| Record | What the paper reports | Type | Population | Caution | Source |
|---|---|---|---|---|---|
| R32-C79 | In SCALE Obesity and Prediabetes, adults without type 2 diabetes receiving liraglutide plus lifestyle counselling lost a mean 8.4 kg over 56 weeks, compared with 2.8 kg with placebo plus counselling. | direct evidence | Adults with overweight or obesity without T2D; 61.2% had prediabetes | 56 weeks; attrition details unavailable in abstract. Three-year extension 28237263 excluded because correction-linked. No across-trial comparison. | PubMed 26132939 |