How do injectable weight-loss medications work? Here’s what to know before meeting with your doctor

Joanna Kriehn, MS, RDN, CDCES - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist (CDCES)

Injectable weight-loss medications have risen in popularity. But, before talking with your doctor about prescribing one to accompany your weight-loss efforts, here's what you need to know.

Here’s how injectable weight-loss medications like Wegovy work

Glucagon-like peptide 1, or GLP-1, is a hormone produced naturally in the body. It releases in response to eating, working with your brain and digestive system to slow down how fast food moves through the gut and processes after eating. Wegovy and other brands of injectable weight-loss medication are known as GLP-1 agonist medications which mimic the hormone's action.

GLP-1 receptor agonist medications stimulate the GLP-1 receptors to:

• Slow gastric emptying
• Increase satiety
• Secrete insulin (an essential hormone involved in blood sugar regulation).
• Inhibit glucagon (a hormone involved in blood sugar regulation).

These injectable weight-loss medications reduce cravings and help you feel full on smaller amounts of food.

What injectable weight-loss medications are available?

Liraglutide (sold as Saxenda) was FDA approved in 2014. Used in conjunction with a reduced-calorie diet, it is administered once daily.

Semaglutide (sold as Wegovy) was FDA approved in 2021. It is a once-weekly injection used along with a reduced-calorie diet.

Both medications were initially approved to treat type 2 diabetes. The new indications include treatment of obesity (BMI > 30) without diabetes and in adults with a BMI > 27, along with weight-related health issues. Both medications require a prescription.

How much weight can I expect to lose with these medications?

One study lasting 68 weeks compared liraglutide to semaglutide for weight loss. Patients taking weekly semaglutide lost 15.8% vs. 6.4% for those taking liraglutide. Note, however, that Novo Nordisk manufactures both drugs and funded this study comparing the effectiveness of these drugs.

Reviews of 10 studies found semaglutide was superior among injectable weight-loss medications at reducing participants’ body weight compared to a placebo.

What possible side effects could I experience?

• Nausea
• Diarrhea
• Vomiting
• Constipation
• Abdominal pain
• Headache
• Hypoglycemia
• Dizziness
• Increased heart rate
• Kidney problems
• Fatigue
• Allergic reaction
• Drug interactions

Less common but more severe side effects

Acute pancreatitis
Acute gallbladder disease
Thyroid cell tumors
Depression or thoughts of suicide
Diabetic retinopathy in individuals with type 2 diabetes

Do not use if the following applies:

Personal or family history of medullary thyroid carcinoma (MTC)
Patients with multiple endocrine neoplasia syndrome type 2 (MEN 2)
Individuals with eating disorders including individuals who are overweight and have an eating disorder
Individuals who are fearful of injections

Note:
Because these medications reduce blood sugar, it is recommended to avoid alcohol when taking medicines that can lower blood sugar.

Cost

Many health insurance companies do not cover the cost of these injectable weight-loss medications. However, coverage is more common for individuals prescribed these medications to manage their type 2 diabetes. Out-of-pocket costs for the drug can run around $1,500/month.

What if I stop taking these injectable weight-loss medications? Will I regain the weight?

Weight regain is likely after stopping these medications. Simply put, if you do not address the habits that led to the gain in the first place, weight will come back. However, by making lifestyle changes, you can likely prevent weight regain.

Natural strategies to promote weight loss

Interested in trying to lose weight naturally? These tips can get the scale moving downward.

• Set a realistic weight-loss goal. Losing weight too quickly from underfueling means increased risk of nagging hunger and nutrient deficiencies.
• Eat regular and balanced meals. Sometimes people skip meals as a way to create a negative energy balance. Yet, this can backfire, setting you up for late-night scrounging. To find a template for building a balanced meal, click here.
• Fit movement into your day. If you don’t have time to engage in longer workouts, these fitness snacks will help you stay moving throughout the day.
• Track your intake and follow a calorie budget. MyNetDiary makes it easy to figure out how many calories you need to reach your weight-loss goals. Log as soon as you eat. Don’t let “calorie amnesia” set in.
• Losing weight is challenging, and there’s no reason to go it alone. MyNetDiary offers online assistance through a community forum. Accessible from iOS or the web app, it is a safe place to share successes or ask questions.

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