Your first weeks on GLP-1: what to expect and what to do

Body aches in the first few days: is it normal?

Yes. Many people experience muscle aches, joint pain or a general flu-like feeling during the first 24-72 hours after their injection, especially with the earliest doses. It can feel like mild body aches, fatigue and sometimes a headache.

This happens because your body is adjusting to the medication. In clinical trials of tirzepatide (Mounjaro), up to 12% of participants reported fatigue and 5% reported muscle pain. Figures for semaglutide (Ozempic/Wegovy) are similar.

What to do:

• Rest as needed — don't push yourself for the first 2-3 days after your shot.
• Stay hydrated: aim for at least 50-70 oz (1.5-2 liters) of water per day.
• If the pain is severe or doesn't improve within 4-5 days, contact your doctor.

In most cases, these symptoms ease significantly after the first 2-3 doses as your body adapts.

I have zero appetite: how do I eat?

Appetite suppression is one of the main effects of GLP-1 medications: semaglutide and tirzepatide act directly on the brain's satiety centers. Feeling like you don't want to eat at all is an expected response, especially during the first few weeks.

The problem is that eating too little can cause nutritional deficiencies, muscle loss and fatigue. Even if you're not hungry, your body still needs fuel.

Practical strategies:

• Eat by the clock — schedule meals instead of waiting for hunger. 3 small meals + 2 snacks works well.
• Start with protein — fullness kicks in fast, so the first thing you eat should be the most nutritious.
• Keep portions small — a large plate feels overwhelming. Use smaller dishes.
• Choose nutrient-dense foods — Greek yogurt, eggs, nuts, avocado. More useful calories in less volume.
• Protein shakes — if chewing feels like a chore, a shake with protein powder, fruit and milk is a complete meal in a glass.

If you've gone more than 48 hours barely eating, contact your doctor.

Protein: your number one priority

Prioritizing protein is exactly the right move. When you lose weight, a portion (20-30%) can be lean muscle mass. Protein is the single most important factor for preserving it.

How much do you need?

• The general recommendation during GLP-1-assisted weight loss is 1.0-1.6 g of protein per kg of body weight per day (or roughly 0.5-0.7 g per pound).
• Example: if you weigh 180 lbs (82 kg), aim for 82-131 g of protein daily.
• Spread your intake across all meals — your body absorbs 25-40 g per sitting better than 80 g in one go.

Good sources:

• Chicken, turkey, fish, shrimp.
• Eggs (6 g per egg).
• Greek yogurt (15-20 g per serving).
• Legumes (lentils, chickpeas).
• Tofu, tempeh.
• Protein powder (whey or plant-based) as a supplement.

Exercise: how much is too much?

Exercising during GLP-1 treatment is highly recommended — in fact, it's one of the most important factors for preserving muscle mass. But there are nuances.

Is full-body training 4 times a week okay?

It depends on your starting point. If you were already working out before starting the medication, maintaining your routine is reasonable. If you're starting exercise at the same time as the medication, going from 0 to 4 strength sessions per week is a lot at once.

General guidelines:

• Strength training: 2-3 sessions per week of resistance exercises (weights, bands, bodyweight). This is what protects your muscle the most.
• Cardio: 150 minutes per week of moderate activity (brisk walking, cycling, swimming). It doesn't need to be intense.
• Progress gradually: if you're a beginner, start with 2 days of strength + walking, and increase every 2-3 weeks.
• Listen to your body: on post-injection days you may feel more tired or achy. It's perfectly fine to take it easy or rest.

Exercise doesn't counteract the medication — it complements it. But don't compensate for lack of appetite with longer workouts: your body needs fuel to recover.

3 pounds in one week: is that too fast?

Losing 3 lbs (about 1.5 kg) in your first week is common and shouldn't worry you. Much of that initial loss is retained water and gastrointestinal content — not all of it is fat.

What's a healthy pace?

• During the first 2-4 weeks, it's normal to lose faster (2-4 lbs/week) as your body adjusts.
• After that, a sustainable rate is 1-2 lbs per week (0.5-1 kg).
• If you're consistently losing more than 4 lbs per week, talk to your doctor — you may be losing too much muscle mass.

Don't obsess over daily weigh-ins. Day-to-day fluctuations of 1-2 lbs are normal (hydration, digestion, hormonal cycle). What matters is the weekly trend.

Hair loss: why it happens and what to do

This is one of the most common concerns. Hair loss associated with GLP-1 medications is called telogen effluvium and is caused by rapid weight loss, not by the medication itself.

Why does it happen?

When your body experiences a sudden change — stress, surgery, a very restrictive diet or rapid weight loss — a larger proportion of hair follicles enters the resting phase (telogen). About 2-4 months later, that hair falls out. It's temporary.

How common is it?

In the SURMOUNT trials (tirzepatide), alopecia was reported in 4-6% of participants on the highest dose, compared to 1% on placebo. In the STEP trials (semaglutide), the incidence was similar.

What you can do to minimize it:

• Get enough protein: hair is made of keratin (a protein). A protein deficit makes shedding worse.
• Iron and ferritin: ask for a blood test. Low ferritin levels (below 40-70 ng/mL) are linked to hair loss.
• Biotin (vitamin B7): 2,500-5,000 mcg daily. There's no strong evidence it prevents telogen effluvium, but it's safe and may help if you're deficient.
• Zinc: 15-30 mg daily. Plays a role in hair growth.
• Vitamin D: deficient in many GLP-1 patients. Ask your doctor to check your levels.
• Don't lose weight too fast: a more gradual pace reduces your body's stress response.
• Be patient: telogen effluvium is reversible. Hair typically recovers within 6-12 months once your weight stabilizes.

If the shedding is very heavy, diffuse or lasts longer than 6 months, see a dermatologist to rule out other causes.

General tips for the first weeks

• Stay hydrated: aim for at least 70 oz (2 liters) of water per day. Loss of appetite also reduces your thirst.
• Daily multivitamin: a cheap insurance policy against deficiencies. Look for one that includes iron, zinc, B12, folic acid and vitamin D.
• Track your symptoms: keep a daily log of how you feel. It will help you and your doctor spot patterns. Andre does this for you automatically.
• Don't compare: every body responds differently. The person who lost 10 lbs in the first week is not your benchmark.
• Be patient with side effects: nausea, fatigue and digestive discomfort usually improve a lot after the first 3-4 weeks.
• Don't skip meals: even if you're not hungry, your body needs nutrients to function and for your workouts to actually work.

Related guides

• What to eat during GLP-1 treatment — gentle foods, plate structure and nutritional deficiencies.
• Nausea: what's normal and when to consult — why it happens, how long it lasts and warning signs.
• 8 GLP-1 myths — what the science says about muscle, weight, thyroid and more.

Sources: SURMOUNT-1 Trial (Jastreboff et al., NEJM 2022); STEP 1 Trial (Wilding et al., NEJM 2021); Obesity Medicine Association — GLP-1 Nutrition Guidelines (2025); Malkud S., Int J Trichology 2015 (telogen effluvium); Cleveland Clinic — Hair Loss and Weight Loss (2024); Frontiers in Nutrition — Micronutrient Deficits in GLP-1 Users (2025).