Effect and side effect at the same time
Most side effects are unwanted extras. Appetite on Saxenda® is different, because the documents describe it in two roles. In the pharmacology sections, lower appetite is the mechanism: GLP-1 receptors sit in brain areas that regulate appetite, and liraglutide lowers weight through reduced calorie intake. [1][2] In the safety sections, it can also appear as a reported reaction, counted when a trial participant described it as an adverse event.
How each document treats the second role differs, which is why a quick search can seem contradictory.
| Document | Adults on Saxenda® | Placebo | Notes |
|---|---|---|---|
| Canadian monograph, Table 3 [3] | 10.0% (337 of 3,384) | 2.3% (45 of 1,941) | Reactions in ≥1% and above placebo |
| Canadian patient information [3] | “Very common” | — | Listed as lower appetite |
| US label, Tables 2–3 [1] | Not listed | — | Mechanism described in section 12 |
| EU SmPC, section 4.8 [2] | Not listed | — | Satiety and hunger effects described in section 5.1 |
| MedlinePlus, liraglutide [7] | Listed | — | Report if severe or it does not go away |
What controlled studies measured
A five-week crossover study in 49 adults with obesity and no diabetes compared liraglutide 1.8 mg, liraglutide 3 mg and placebo. Both doses raised ratings of satiety and fullness after a meal, lowered hunger and expected food intake, and reduced the amount eaten at a free-choice lunch by roughly 16%. Energy expenditure did not rise. [4] The study was funded by the manufacturer and was short, but it is the basis for the mechanism described in the Canadian monograph. [3]
A 16-week placebo-controlled study at Mayo Clinic added a different angle. In 35 adults who completed it, liraglutide 3 mg reduced the desire to eat something sweet, salty, savoury or fatty and lowered the volume of a nutrient drink people could finish, while body fat fell without a measurable loss of lean mass. [5] A systematic review of 12 randomised trials of GLP-1 medicines in adults with obesity reported the same general picture of less hunger, slower stomach emptying and shifts in food preference. [6]
Why appetite drops on a daily injection
- Supported by the labels: liraglutide acts on GLP-1 receptors in appetite-regulating brain areas, and slows stomach emptying. [1][2] The Canadian monograph measured a 23% smaller paracetamol signal in the first hour after a meal, a marker of slower emptying. [3]
- Proposed in research: changes in food preference and in gut hormones such as PYY were observed with liraglutide 3 mg, though how much each contributes is not settled. [5]
- General: nausea, which affected 39% of adults on Saxenda® in the US trial pool against 14% on placebo, can also make food unappealing, especially while the dose rises. [1] MedlinePlus notes that low mood, illness and some medicines reduce appetite on their own. [9]
When less hunger becomes too little food
The label is built around a reduced-calorie diet, not an extreme one. Several warnings in it become more relevant if eating and drinking drop sharply. Nausea, vomiting or diarrhoea can lead to dehydration and, in post-approval reports, kidney injury; the Medication Guide asks you to drink fluids and report digestive symptoms that do not go away. [1] Substantial or rapid weight loss raises the risk of gallstones, which the label lists as a warning. [1]
People with type 2 diabetes who use insulin or a sulfonylurea have a higher risk of low blood sugar on Saxenda®, and in the adolescent trial, where no one had diabetes, symptomatic low blood sugar was reported by 15.2% on the medicine and 4% on placebo. [1] Hunger, shakiness, sweating and confusion are among its signs, so a sudden urge to eat with those symptoms needs checking rather than ignoring. [1]
The EU summary notes that safety has not been established in obesity caused by an eating disorder. [2] MedlinePlus advises seeking help when poor appetite comes with signs of depression or an eating disorder. [9]
Other things that dull appetite
MedlinePlus lists a wide range of causes of decreased appetite: sadness, depression or grief; an underactive thyroid; liver, kidney, lung or heart disease; infections such as hepatitis; early pregnancy; and medicines including some antibiotics and opioid painkillers. [9] Unexplained weight loss beyond what you and your prescriber expect is one reason to look for these.
What the guidance describes
The Saxenda® label pairs the medicine with a reduced-calorie diet and more physical activity, and NIDDK describes weight-management medicines as working alongside healthy eating and activity rather than replacing them. [1][8] MedlinePlus suggests that people who are eating poorly keep a record of what they eat and drink for a day or more, which helps a clinician judge whether intake is adequate. [9]
The label allows the injection at any time of day, regardless of meals, so there is no labelled “best time” for appetite. [1] If loss of appetite seems linked to the medicine, MedlinePlus advises discussing it with your provider rather than stopping on your own. [9]
Saxenda® and Victoza® are registered trademarks of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Severe stomach pain that will not go away, sometimes reaching the back | Stop the injection and call your prescriber or emergency services | Emergency | Medication Guide [1] |
| Unable to keep fluids down, with vomiting or diarrhoea that does not settle | Your prescriber | Today | Medication Guide [1] |
| Shakiness, sweating, sudden hunger or confusion if you use insulin or a sulfonylurea, or are a teenager on Saxenda® | Check blood sugar as instructed and contact your care team | Today | Medication Guide [1] |
| Loss of appetite with low mood, loss of interest, or worry about eating behaviour | Your doctor or a mental health professional | At your next appointment | MedlinePlus [9] |
| Appetite so low that you struggle to eat regular meals for days | Your prescriber | At your next appointment | MedlinePlus [7] |
