GLP-1 Drugs: Pros, Cons, and Dietitian Tips for Managing Side Effects

By: Janelle Huybers, Registered Dietitian

Looking to Start a GLP-1 Medication? Start Here

GLP-1 weight loss medications seem to have gone mainstream, meaning more and more people are talking about them, trying them, or considering them as part of their weight management journey. As dietitians, we support our clients with the approach they choose, helping them make the most of it safely and effectively.

GLP-1 receptor agonists (GLP-1 RAs) such as semaglutide, liraglutide, and tirzepatide can lead to significant weight loss, but there are pros and cons. Read on and get unbiased information on what to expect and learn about solutions to common concerns. 

What the Research Says: Efficacy, Benefits, and Limitations

• In many clinical trials, GLP-1s produce 15-25% body weight loss over roughly 1 year in people with obesity under good care. (MDPI)
• But weight loss tends to plateau, and when the medication is stopped, many people regain a large proportion of what was lost. One source notes that two-thirds (≈ ~66%) of weight loss can return within a year of stopping. (pcom.edu)
• Also, a large part of the weight lost can be lean mass, such as muscle, which has implications for metabolism and long-term health. For example, semaglutide may have lean mass loss that represents ~45% of total mass lost; for Tirzepatide this may be closer to ~25%. (Oxford Academic)

Mindset: Preparing for the GLP-1 Pros and Cons

Starting a GLP-1 RA isn’t just about imagining the “best version of you”—it also means thinking ahead to what can go wrong or what you’ll have to sustain. Below, we have gathered some of the clinically known pros and cons of the medications.

Weight Loss Medications – What Are The Pros?

• Reduced appetite, satiety improvements, less reward from high-sugar or high-fat foods.
• Potential improvements in metabolic health, such as improved blood sugar control and reduced cardiovascular risk.
• Possibility of steady, clinically meaningful weight reduction.

Weight Loss Medications – What Are The Cons?

• Side effects (see below) that can be uncomfortable, especially early on. Other side effects, such as losing muscle mass and loose skin, are results of weight loss in themselves and can often be offset with nutrition and physical activity. Up to 45% of weight lost on semaglutide can be lean tissue. For women, this risks metabolism slowdown, osteoporosis, and fatigue.
• Duration, access and cost: Many patients need to stay on medication long-term or indefinitely; insurance, regulatory approvals, prescription requirements and costs can pose barriers.
• “Medication dependence”: For most, when you stop the medication, appetite returns. Because stopping can lead to regain, many people fear they’ll be “on this forever.” Right now, the research in this area is still developing, but points towards most people needing medications longterm. Planning a sustainable path is essential, thinking about both options, with and without medication.
• Changing identity and self-image can be hard: going from heavier body to smaller body (if loss is large) means shifts in social interactions, expectations (yours and others’), body image, and sometimes dealing with loose skin, etc. This aspect of weight loss (not only from medications) can be greatly underestimated yet have a huge impact on long-term success. 

Weighing It Out: Questions You Should Be Asking

• What are your goals: health endpoints (e.g. reduce diabetes risk, improve mobility), aesthetic, self-confidence, etc.? Are you willing to commit to long-term behavioural changes?
• Are you ready for possible discomfort and for a period of adjustment (nausea, reduced appetite, etc.)?
• Do you have support (medical, nutritional, physical, psychological)?
• What happens if the medication needs to be discontinued? Do you have a plan for maintenance?

Shifting self-identity matters: for example, seeing yourself not merely as “someone trying to lose weight” but “someone living healthfully, moving well, sustaining a smaller body.” It means internalizing that sustained weight loss isn’t just a phase; it’s a lifestyle.

Common Questions Our Dietitians Are Asked

1) Will I have sagging skin?
Possibly, especially with large or fast losses, not from the medications themselves. Genetics, age, and history of weight cycling matter. Building muscle and nourishing your skin from the inside (protein, healthy fats, hydration) help. Medical or cosmetic interventions are an option if it significantly impacts confidence or comfort.

2) Will this affect my hair? Some women report hair shedding during rapid weight loss (often from stress or nutrient gaps, not the medication itself). Like skin, this is due to weight loss, not the medication. Adequate protein, iron, zinc, and B-vitamins are protective.

3) How do I keep my curves? You can’t fully control fat distribution, but resistance training can help preserve shape and strength. Many women find that muscle adds back contour after fat loss.

4) Is it safe if I want children? GLP-1s are not recommended in pregnancy or while breastfeeding. If planning a pregnancy, discuss timing carefully with your healthcare provider. Always make sure you’re using some form of birth control while on these medications. On the flip side, since GLP-1s can help with PCOS and obesity, GLP-1s may in the long term increase fertility. 

Glp-1 Side Effects: How Common, How Bad, and How to Manage Them

LOSS OF LEAN MUSCLE MASS

Approx Incidence*: Variable; semaglutide ~ 45% of total weight lost; tirzepatide ~ 25%. (Oxford Academic)

Typical Onset / Worst Time: Over the course of weight loss, especially rapid phases.

Strategies & Mitigation: Emphasize resistance/strength training; ensure sufficient protein (often 1.2-1.6 g/kg body weight/day, sometimes more depending on the individual and activity); do not overly restrict calories; monitor body composition, not just scale.

Vomiting also occurs in about 8–24% of cases (ScienceDirect) and often appears early, sometimes triggered by certain foods or large meals. Management strategies are similar to those for nausea. Eating small, bland meals, avoiding lying down after eating, and taking antiemetic medication if prescribed should help. It’s also important to eat slowly to help minimize symptoms.

More Rare / Serious Risks Related to GLP-1 Usage

• Pancreatitis, gallbladder disease: less common, but reported. (GOV.UK)
• Thyroid C-cell tumor risk (based on animal studies): medications have boxed warnings for people with personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia type 2. (pcom.edu)
• Gastroparesis / slowed gastric emptying: may make side effects worse in those with underlying motility issues. (pcom.edu)
• Hypoglycaemia risk: usually small in non-diabetics, but possible especially if other glucose-lowering meds are used or fasting. (GOV.UK)

Does the weight come back after using GLP-1 medications?

• In a study, stopping semaglutide treatment after ~68 weeks resulted in weight regain, though even at 120 weeks, there was still a net loss compared to baseline (but less than at peak). (MDPI)
• Many people come off medications early: some data show that > 30% might stop within first 4 weeks due to side effects, cost, or other barriers. Early discontinuation reduces benefits. (Health)

Bottom Line: Whether or not you’ll take this medication for life or not is unknown, but be prepared to.

Working With a GLP-1 Dietitian: Why It Matters

A dietitian with knowledge in supporting clients on GLP-1 medications enhances patients’ journey and optimizes long-term benefits. A registered dietitian:

• Helps design a meal plan that supports your calorie goal, ensures micronutrient adequacy, and distributes protein across the day.
• Can anticipate and adjust for side effects (e.g. targeting meals to reduce nausea, etc.).
• Provides accountability, troubleshooting, and personalization (food preferences, cultural foods, cost, lifestyle).
• Supports maintenance phase: teaching skills for keeping weight off when medication is stabilized or possibly reduced.

Physical Activity During GLP-1 Medications

Preserving and supporting lean mass, metabolic rate, and function during weight loss is critical.

• Resistance training, such as weights, resistance bands, and bodyweight exercises 2-4 times per week is ideal. Focus on major muscle groups.
  
• Also include aerobic / cardiovascular activity (moderate to vigorous) to support cardiovascular health, energy expenditure, and mood. Aim for something like 150-300 min/week depending on fitness level.
  
• Include balance / flexibility / mobility work (yoga, stretching) so that as weight changes, you’re not losing ease of movement.
• Protein intake is essential: many studies suggest 1.2-1.6 g protein per kg body weight/day; for some individuals, more, especially with high resistance-training load. Pairing protein with resistance training helps limit lean mass loss.

Practical Tips: What to Do Before & During Your GLP-1 Journey?

1) Screening & Medical Clearance

• Make sure to have a medical evaluation (history of pancreatitis, thyroid cancer, GI motility issues)
• Discuss all medications & supplements with your provider to avoid interactions.

2) Gradual Dose Escalation

• Starting low, increasing slowly is almost always the better path to reduce the intensity of side effects.

3) Dietary Strategies for Tolerance

• Eat smaller, more frequent meals rather than large ones.
• Focus on bland, easy-to-digest foods during dose ramps or when you’re feeling off.
• Avoid high-fat or spicy meals early on.
• Keep well hydrated; fluids help with many GI side effects and reduce the risk of dehydration.

4) Supplementation (only if appropriate, check with provider or dietitian)

• Good multivitamin/mineral, if diet is restricted.
• Possible use of probiotics for gut health.
• Magnesium or fibre (gradual increase) for constipation.
• Ginger, peppermint or antiemetics for nausea.

5) Mental / Psychological Preparation

• Work with a coach, therapist, or support group to handle emotional eating, identity issues, and body image changes.
• Visualize your path, including possible setbacks.

Build sustainable habits (sleep, stress management, social supports) because weight loss under medication is easier when other lifestyle factors are well-managed.

GLP-1 Timeline: What Are The Key Stages?

• First few weeks: side effects are more common; appetite changes, fullness, nausea for some. Energy levels may vary. (Tip: Meet with a dietitian before you start).
  
• 3-6 months: often the period of rapid weight loss, improvements in metabolic markers, but also risk of lean mass loss if resistance training & protein are not adequate.
  
• 6-12 months: weight loss often slows; habit building becomes important; side effects often lessen; maintenance and sustainability require new routines.
• After 1 year or more: decisions about continuing medication, tapering, or maintaining lifestyle changes are important. Many people stay on medication long-term; others may reduce dose but need strong behaviour & identity support to maintain.

Putting It All Together: Your GLP-1 Decision Plan

Here’s a possible checklist to use before starting:

• Have I discussed with a medical provider whether I’m a good candidate (medical history, possible contraindications)?
  
• Do I know what dose schedule will look like (when increases happen, expected side effects)?
  
• Have I set realistic goals (health, mobility, quality of life) beyond the number on the scale?
  
• Am I ready to commit to resistance training + adequate protein + regular follow-ups?
  
• Do I have a dietitian or nutrition plan in place?
  
• What is my “maintenance” plan if I reach my weight goal? What if I discontinue medication?

Final Thoughts

GLP-1 medications are a powerful tool. For many people, they unlock a window of opportunity: appetite is reduced, satiety improves, weight begins to come off. But they are not sufficient on their own. Sustained weight loss — keeping off what you lose, preserving strength, living well — requires a combination of mindset, identity transformation, resistance food training, nutritional support, medical monitoring, and planning for the long haul.

If you go in eyes open, with realistic expectations, good support, and a readiness to do more than “take a pill,” you increase your chances greatly for long-term success.

Author:

Janelle Huybers, RD, DDEPT, is a Registered Dietitian passionate about helping people live healthy, active, and balanced lives. Growing up on a farm and as a young athlete, she developed an early appreciation for the role of nutrition in wellness and disease prevention. Janelle’s counselling focuses on creating personalized, practical, and enjoyable approaches to healthy eating, empowering clients to build a positive, lasting relationship with food.

“I accept that health is defined differently by everyone, and that there is no one-size-fits-all approach to healthy living.”

Sources:
https://www.mdpi.com/2218-273X/15/3/408
https://www.pcom.edu/south-georgia/news/safety-benefits-and-side-effects-of-glp-1-weight-loss-medications.html
https://academic.oup.com/endo/article/166/2/bqae167/7954557
https://www.sciencedirect.com/science/article/pii/S0002916525002400
https://www.gov.uk/drug-safety-update/glp-1-receptor-agonists-reminder-of-the-potential-side-effects-and-to-be-aware-of-the-potential-for-misuse
https://www.health.com/weight-management-glp1-short-term-use-8653655Health