GLP-1 medications are becoming increasingly popular for weight loss. However, it is important to understand how these medications function to lose weight.

Weight loss medications, such as semaglutide and tirzepatide, do much more than just ‘burning fat.’ These medications fundamentally change appetite, hunger, the feeling of fullness, how much food one eats, and how the body processes and regulates blood sugar. Newer drugs, such as tirzepatide, affect more than one hormone pathway. For example, these drugs can treat diabetes and obesity.

Recent studies show that with these medications and weight loss drugs, people can safely lose a significant amount of weight. In 2026, the FDA approved the high dose of Wegovy HD (semaglutide 7.2 mg) for certain adults overweight and with obesity and weight related co-morbidities.

What Are GLP-1 Medications?

GLP-1 stands for glucagon-like peptide-1, a hormone that is secreted after a meal is ingested.
GLP-1 medications stimulate the effect of the hormone.
Semaglutide and tirzepatide fall under this category.

In the United States, semaglutide (Wegovy) and tirzepatide (Zepbound) are some examples approved by the FDA for chronic weight management.

How Do GLP-1 Medications Work to Cause Weight Loss?

They Control Hunger

This is specifically related to weight loss.

GLP-1 receptors are involved in the cognitive and physical regulation of hunger and food consumption. New medicines that target GLP-1 medications have been shown to lessen hunger pangs and increase the sense of satiation or fullness. Additionally, they have the capacity to decrease appetitive food cravings and aid in the control of caloric consumption.

From this, we can infer that use of GLP-1 receptor related therapies may help control hunger, thus facilitating the maintenance of a caloric deficit.

They Help You Feel Full Longer

GLP-1 receptor activating drugs increase satiation.

If you feel satisfaction sooner, you may feel less likely to snack between meals and may even begin to eat less overall, helping with weight loss.

It should be clear that GLP-1 related drugs do not help to “melt fat.”Most of their weight loss effect has to do with the drug aiding the body to regulate hunger, thereby decreasing food consumption.

They Can Slow Stomach Emptying

GLP-1 medications therapy can slow stomach emptying (gastric emptying) after food passes through the stomach.

This may lead to increased fullness and longer satiation, as well as the decreased rise of blood glucose levels after eating a meal.

They Influence Blood Sugar and Insulin

These drugs have functions within blood-glucose regulation as well.

GLP-1 medications stimulation helps to respond to increased blood sugar levels by releasing insulin and inhibits inappropriate glucagon release. These activities result in better blood sugar control, especially in type 2 diabetes patients.

Though many factors are at play, controlling blood sugar levels is also a primary cause for weight loss in patients taking diabetes medications.

Tirzepatide Targets Two Hormone Pathways

Unlike other GLP-1 medications agonists, tirzepatide has the ability to stimulate both GLP-1 and GIP receptors.

It is believed that this unique ability allows tirzepatide to influence different pathways related to appetite, food intake, blood sugar, and energy levels.

The SURMOUNT-1 clinical study showed promising results for tirzepatide, with patients given 10 mg, and 15 mg dosages of the study drug, having a mean (average) weight loss of 19.5% and 20.9%, respectively, at 72 weeks. This was compared to the weight loss of 3.1% on the placebo.

It is no wonder that tirzepatide has quickly gained a place in obesity treatment.

What Does the Research Say About Semaglutide?

Another strong early study for semaglutide weight management research was the STEP 1 study.

This study included overweight or obese participants without diabetes. These participants received either placebo or semaglutide 2.4 mg along with weekly doses, and lifestyle intervention for 68 weeks.

The mean percent of weight loss was:

Treatment	Average Weight Change at 68 Weeks
Semaglutide 2.4 mg	−14.9%
Placebo	−2.4%

Approximately 86.4% of semaglutide participants and 31.5% of placebo participants lost 5% of their weight.

The study noted improvements in other measures such as waist circumference, blood pressure, blood glucose, and several lipid levels.

Do GLP-1 Medications Work Without Diet and Exercise?

These drugs can facilitate some weight loss, but they should not be thought of as substitutes for diet and exercise.

Current FDA approval for Wegovy and Zepbound states that they are for use with reduced-calorie diets and increased physical activity.

During treatment, balanced diets with adequate protein and fiber, and increased physical activity, along with healthy habits such as sleep, remain important.

What are the side effects?

Being digestive and appetite related, GLP-1 medications usually cause gastrointestinal problems.

Some examples of these are:

Nausea
Diarrhea
Vomiting
Constipation
Abdominal pain
Lack of appetite

In the STEP 1 trial, nausea and diarrhea were among the most common side effects with semaglutide, and were of mild to moderate severity.

Some serious conditions can arise, including gallstones and pancreatitis, and other gastrointestinal disorders that can cause kidney failure and be very severe. These drugs should not be used by anyone for any reason.

What Happens If You Stop a GLP-1 Medication?

GLP-1 medications help to facilitate some weight loss, and once discontinued, the appetite tends to return and the weight tends to come back.

This explains why many health organizations place obesity in a lifetime management category, as opposed to a curable category.

Your healthcare provider is the only one who can decide if you need to continue treatment.

Final Thoughts

Medications that stimulate GLP-1 can help people lose weight by reducing hunger and increasing satisfaction, curbing cravings, slowing the emptying of food from the stomach, and enhancing the management of blood sugar levels. Unlike other medications, tirzepatide also targets GIP and thus, partly, another pathway to tackle weight loss.

Several studies have identified significant weight loss with the use of semaglutide and tirzepatide, though they are known to produce variable results. These medications should be used with extreme caution and in combination with changes to diet and exercise under the guidance of a healthcare professional.

People are advised to schedule a consultation with their primary care physician to evaluate if taking a GLP-1 medication for weight loss is safe and adequate based on their health and weight-loss goals.