Liraglutide for Weight Loss: How It Works and What to Expect

Liraglutide is an injectable prescription medication used for chronic weight management. It belongs to a class of drugs known as glucagon-like peptide-1 (GLP-1) receptor agonists. While originally developed to treat type 2 diabetes under the brand name Victoza, a higher-dose version called Saxenda was later approved by the FDA specifically for weight loss.

How Liraglutide Promotes Weight Loss

Liraglutide works by mimicking a naturally occurring hormone in the body called glucagon-like peptide-1 (GLP-1). This hormone is released by cells in the intestine after a person eats. Liraglutide, which shares 97% of its structure with human GLP-1, activates the same receptors to produce its effects.

A primary action of liraglutide occurs in the brain. It targets receptors in the hypothalamus, a region that regulates hunger and food intake. By stimulating these receptors, the medication helps to reduce appetite and increase feelings of fullness, or satiety, leading to a lower overall calorie consumption.

The medication also affects the digestive process directly. It slows down gastric emptying, which is the rate at which food moves from the stomach into the intestines. This delay means food remains in the stomach for a longer period, contributing to a prolonged sense of fullness after meals.

Efficacy and Expected Results

Clinical studies have demonstrated that liraglutide can lead to meaningful weight loss for many individuals when combined with lifestyle modifications. The SCALE (Satiety and Clinical Adiposity—Liraglutide Evidence) trial is a significant study highlighting its effectiveness. In this trial, participants taking the 3.0 mg dose of liraglutide saw better results than those receiving a placebo.

On average, individuals using liraglutide lost between 4 to 6 kg more than those in the placebo group. A higher percentage of people taking the medication achieved specific weight loss milestones. For instance, about half of the participants on liraglutide lost at least 5% of their initial body weight, while about a quarter lost at least 10%, compared to lower rates in the placebo group.

These results were achieved in a clinical setting where participants were also counseled on a reduced-calorie diet and an increased physical activity regimen. The amount of weight a person loses can vary based on adherence to these lifestyle changes. Liraglutide is considered an adjunct to diet and exercise, not a standalone solution.

Administration and Dosing Schedule

Liraglutide, when prescribed for weight management as Saxenda, is administered through a once-daily subcutaneous injection. This means the medication is injected into the fatty tissue just under the skin, typically in the abdomen, thigh, or upper arm. The medication is supplied in a pre-filled pen device, which allows for easy dose selection and administration.

Treatment begins with a low starting dose that is gradually increased over several weeks. This process, known as dose titration, helps the body adjust to the medication and minimize the gastrointestinal side effects that can occur. Patients start with a 0.6 mg dose once daily for the first week.

Each subsequent week, the daily dose is increased by 0.6 mg until the full therapeutic dose of 3.0 mg per day is reached at the start of the fifth week. Patients continue on the 3.0 mg dose for the duration of their treatment, unless advised otherwise by their healthcare provider.

Potential Side Effects and Safety Profile

The most common side effects associated with liraglutide are primarily gastrointestinal. These frequently include nausea, diarrhea, constipation, and vomiting. Such effects are often most pronounced when first starting the medication or after a dose increase and tend to diminish over time as the body adapts.

There are also more serious, though less frequent, risks. Liraglutide carries an FDA-issued boxed warning regarding a risk of thyroid C-cell tumors. This warning is based on studies in rodents where liraglutide caused these tumors; it is not known if this risk applies to humans. Consequently, it is contraindicated for individuals with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.

Other potential risks include pancreatitis (inflammation of the pancreas) and gallbladder problems like gallstones. Symptoms of pancreatitis, such as severe abdominal pain that may radiate to the back, require immediate medical attention. An increased heart rate and a risk of low blood sugar (hypoglycemia), particularly when used with other diabetes medications like insulin, have also been reported.

Who Qualifies for Liraglutide Treatment

The FDA has specific criteria for prescribing liraglutide (Saxenda) for chronic weight management in adults. A person may be eligible if they have a Body Mass Index (BMI) of 30 kg/m² or greater, which is classified as obesity. An individual may also qualify if they are overweight, with a BMI of 27 kg/m² or greater, and have at least one weight-related health condition.

These associated conditions include common health issues such as hypertension (high blood pressure), type 2 diabetes, or dyslipidemia (high cholesterol).

Liraglutide is also approved for use in adolescents. The criteria for adolescents aged 12 to 17 include having a body weight above 60 kg (approximately 132 pounds) and an initial BMI that corresponds to adult obesity (30 kg/m² or higher).

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