GLP-1 receptor agonists are a popular class of medications used to help manage type 2 diabetes and, more recently, support weight loss. Semaglutide injections, in particular, are commonly prescribed for these purposes. Some people report fatigue as a side effect when starting these injections, especially during the initial adjustment period.
If you’ve recently started a GLP-1 medication or are considering one and are worried about feeling unusually tired, here’s what you need to know about the possible link between GLP-1s and fatigue so you can make an informed decision.
Key Takeaways
- GLP-1 medications mimic natural hormones that help regulate appetite, insulin production, and blood sugar levels, making them effective for managing type 2 diabetes and supporting weight loss.
- Fatigue isn’t an official side effect of GLP-1 medications, but many people experience temporary tiredness, especially when first starting treatment.
- The first few weeks of treatment are when fatigue is most common, as your body adjusts to metabolic and digestive changes caused by the medication.
- Balanced nutrition is important because GLP-1s reduce appetite, so eating smaller, nutrient-dense meals with lean proteins, complex carbs, and healthy fats can help maintain steady energy levels.
What Are GLP-1 Medications?
Glucagon-like peptide-1 receptor agonists, commonly known as GLP-1s or GLP-1 RAs, are medications that mimic the effects of the natural hormone GLP-1 your body releases after eating. This natural hormone plays several key roles: it helps you feel full, signals the pancreas to produce and release insulin, and assists in regulating blood sugar levels.
Originally developed to help manage type 2 diabetes, GLP-1 medications are effective at stabilizing blood sugar. However, because they also slow digestion and promote feelings of fullness, many people who take them experience weight loss as a secondary effect.
Over time, several GLP-1 medications first approved for diabetes management have inspired companion drugs specifically designed for weight loss. For instance, semaglutide treatment is now used both for diabetes management and as an obesity treatment. Ozempic, a GLP-1 medication for type 2 diabetes, contains semaglutide as its active ingredient, the same ingredient found in Wegovy, which is FDA-approved for weight management.
Beyond diabetes and weight loss, GLP-1s have also been linked to improved heart health, with research showing they may lower the risk of cardiovascular disease, heart attack, and stroke. Emerging studies are exploring whether GLP-1s could also help slow the progression of kidney disease, though current findings are still preliminary.
Types of GLP-1 Medications
There are several different types of GLP-1 medications you can potentially use, both for managing diabetes or for weight loss. The three most common active ingredients used in GLP-1s are semaglutide, liraglutide, and tirzepatide.
Semaglutide-based GLP-1s include Ozempic (diabetes medication), Rybelsus (diabetes), and Wegovy (weight loss medication). The semaglutide dose varies between these medications—Wegovy is typically prescribed at a higher dose (2.4 mg) for weight loss, while Ozempic is used at lower doses (0.5-1.0 mg) for diabetes. Higher doses of semaglutide, such as those in Wegovy, are associated with a greater likelihood of fatigue compared to lower doses like Ozempic. It’s important to consult a healthcare provider to determine the appropriate semaglutide dose and to gradually adjust the dose to help minimize side effects like tiredness.
Liraglutide-based GLP-1s include Victoza (diabetes) and Saxenda (weight management). Tirzepatide-based medications include Mounjaro (diabetes) and Zepbound (weight loss).
Common GLP-1 Side Effects
The most common side effects when taking GLP-1 medications are gastrointestinal problems, such as nausea, vomiting, diarrhea, constipation, abdominal pain, and bloating. However, some users also report mild fatigue, mood swings, and sleep disruptions, even though these are less common than gastrointestinal side effects. Non-gastrointestinal side effects are also common, such as headache, dehydration, and injection site reactions.
Every GLP-1 medication has slightly different side effects, so if you know which one you’re going to be starting, it’s a good idea to take a look at the side effects for that specific drug so you know what to be aware of.
What Causes Fatigue When Taking GLP-1s?
Drug manufacturers don’t typically list fatigue as a side effect caused by their medications, but many people who use them report feeling unusually tired. Some people experience semaglutide related fatigue or semaglutide fatigue, which is distinct from general tiredness. So, do GLP-1s actually cause fatigue, or is something else at play?
The truth is that GLP-1s don’t directly cause fatigue, but they can contribute to tiredness for a few different reasons related to how they affect your metabolism and digestive system. When starting semaglutide, people often eat significantly less due to appetite suppression, leading to a significant reduction in food intake and fewer calories consumed. This reduced caloric intake semaglutide creates a calorie deficit, which can cause you to experience fatigue or feel tired as your body adapts. The way your body processes food and stores energy also changes, as semaglutide affects how your body uses food and stores energy, resulting in metabolic shifts. These changes can lead to temporary energy crashes, especially during the initial adjustment period, which typically lasts a few weeks to a couple of months and may make these symptoms more pronounced.
Metabolic Adjustments
When you begin taking a GLP-1 medication, your body undergoes several metabolic changes. Semaglutide changes the way the body processes food and stores energy, leading to metabolic adaptations that can cause temporary fatigue. These drugs slow digestion, help control blood sugar, and reduce appetite. While these effects are beneficial, the adjustment period can temporarily affect your energy levels—especially during the first few weeks of treatment or when your dosage increases.
Gastrointestinal Side Effects
The most common side effects of GLP-1 medications are gastrointestinal, including nausea, diarrhea, vomiting, constipation, and abdominal discomfort. These symptoms can sap your energy and, if persistent, may lead to fatigue. In particular, gastrointestinal issues like vomiting or diarrhea can leave you feeling drained or physically exhausted, especially if dehydration or electrolyte imbalance occurs. Additionally, fluid loss from vomiting or diarrhea can cause dehydration, which is another common cause of tiredness. Staying hydrated is especially important while taking GLP-1s.
Blood Sugar Fluctuations
GLP-1 medications help regulate blood sugar, but as your body adjusts, particularly if you’re eating less, you might experience occasional fluctuations in blood glucose levels. Low blood sugar can occur, especially in people with diabetes, and is a known cause of fatigue, shakiness, sweating, and confusion. Maintaining good blood sugar control is important to prevent energy crashes and support stable energy levels. Low or rapidly changing blood sugar can make you feel sluggish or fatigued until your body stabilizes.
In short, while GLP-1s themselves don’t inherently make you tired, the metabolic changes and side effects they trigger can lead to temporary fatigue for some users.
How Long Does Fatigue from GLP-1 Medications Last?
The duration of fatigue can vary widely from person to person, depending on individual factors such as metabolism, dosage, and how the body adapts to the medication.
Fatigue tends to be most common during the first few weeks after starting a GLP-1 medication. Even at the lowest starting dose, your body is adjusting to changes in appetite, digestion, and blood sugar regulation, all of which can temporarily affect your energy levels.
Early Phase (Weeks 1 through 4)
During the initial phase, starting semaglutide or receiving semaglutide injections often leads to daytime fatigue. This is your body’s adjustment period as it gets used to the effects of the medication. Some people report difficulty sleeping during the early weeks of treatment, which can further contribute to tiredness and decreased energy. Side effects like nausea or changes in eating habits can also contribute to low energy during this time.
Adaptation Phase (Weeks 5 through 12)
As your body becomes more accustomed to the medication, fatigue usually decreases. However, it can still occur when you increase your dose, since each adjustment may trigger new metabolic and digestive changes. During this adaptation phase, changes in sleep patterns and occasional sleep disruptions may also occur, which can contribute to feelings of tiredness.
Maintenance Phase (After 12 Weeks)
Once you reach a stable, ongoing dose, most people find that fatigue naturally subsides. By this point, your body has adapted to the GLP-1’s effects. Some mild tiredness can still happen occasionally, especially if you become dehydrated or aren’t eating enough, but for most people, energy levels return to normal over time.
How to Manage Fatigue from GLP-1 Medications
If you’re feeling more tired than usual while taking a GLP-1 medication, there are several practical steps you can take to help reduce fatigue and support your overall energy levels. A personalized treatment plan can help combat fatigue and support your weight loss journey or health journey, ensuring your approach is tailored to your unique needs and goals.
Stay Hydrated
Dehydration is one of the most common contributors to fatigue while taking GLP-1s, especially if you’ve experienced side effects like nausea, diarrhea, or vomiting. Make sure to drink water consistently throughout the day, and consider adding no-sugar electrolyte drinks or powders to replenish essential minerals. Staying well-hydrated can make a noticeable difference in how you feel.
Adjust Your Diet
Eating a balanced, healthy diet is key to maintaining your energy. Ensure you’re getting enough lean protein, complex carbohydrates, and healthy fats. Since GLP-1s often reduce appetite, it’s important to make the most of smaller meals by prioritizing nutrient-rich foods. If you’re unsure about your dietary balance, a registered dietitian can help you create a plan tailored to your needs and energy levels.
Exercise Regularly
Consistent light physical activity can boost circulation, improve metabolism, and help combat feelings of fatigue. Activities like walking, swimming, or yoga for at least 20 minutes a day can make a big difference—but any form of movement is beneficial. Listen to your body and increase intensity gradually as your energy improves.
Get Quality Sleep
Poor sleep can worsen fatigue, so aim for a consistent bedtime and wake-up routine. Create a restful environment by minimizing noise, limiting screen time before bed, and using blackout curtains if needed to avoid disrupted sleep. Quality sleep hygiene supports your body’s ability to recover and adapt to the medication’s effects.
Monitor Blood Sugar Levels
If you’re taking a GLP-1 medication for type 2 diabetes, regular blood sugar monitoring is essential. Tracking your levels can help you identify fluctuations that might be contributing to tiredness. Keeping a record of your readings can also provide valuable insights for your healthcare provider when determining whether your dosage or treatment plan needs adjustment.
Know What to Expect From GLP-1 Fatigue
Although fatigue isn’t officially listed as a side effect of GLP-1 medications, many people experience tiredness, especially during the first few weeks of treatment. This fatigue is often connected to other factors such as gastrointestinal side effects, dehydration, or changes in blood sugar as the body adapts to the medication. The encouraging news is that these symptoms are typically temporary and can be managed with a few simple lifestyle adjustments. At the same time, many individuals find that semaglutide supports positive outcomes like shedding pounds and improved health as part of their weight loss journey or overall health journey.
Staying well-hydrated, eating a balanced and nutrient-rich diet, exercising regularly, getting good-quality sleep, and keeping track of your blood sugar can all help you maintain your energy while taking a GLP-1. Nutrition, in particular, plays a key role in how your body responds, so if you’re feeling unusually tired, it may be time to take a closer look at your eating habits.
You don’t have to navigate this process on your own. Schedule a free consultation with a registered dietitian who can help you optimize your nutrition, manage side effects, and lose weight safely and effectively while using a GLP-1 medication, all at no cost to you.
Frequently Asked Questions About GLP-1s and Fatigue
Do GLP-1 Medications Cause Fatigue?
Fatigue isn’t an officially listed side effect of GLP-1 medications, but many people experience fatigue, especially during the first few weeks of treatment or when starting higher doses. This semaglutide related fatigue is described as physical weakness or low energy, and is distinct from general tiredness or sleepiness. It is often linked to dehydration, changes in appetite, blood sugar fluctuations, or your body adjusting to the medication.
Is Any Specific GLP-1 More Likely to Cause Fatigue?
No, the likelihood of fatigue with GLP-1 medications like semaglutide depends on the semaglutide dose. Fatigue is reported to be more common with higher doses of semaglutide, such as those used in Wegovy, compared to lower doses like Ozempic. It’s important to consult a healthcare provider to determine the appropriate semaglutide dose and to gradually adjust the dose to help minimize side effects like fatigue. All GLP-1 medications have similar gastrointestinal side effects that can contribute to fatigue, but the risk increases with higher doses.
Why Does Dehydration Cause Fatigue While Taking GLP-1s?
GLP-1 medications can cause gastrointestinal side effects like nausea, vomiting, or diarrhea, which can lead to dehydration. When your body loses fluids and electrolytes, it can leave you feeling drained or physically exhausted. This feeling drained state is a common cause of fatigue, so staying hydrated is key to preventing it.
