The honest answer is: it's almost certainly both, but the caloric deficit is the bigger driver.

1100-1200 calories is too low for most adults, and a drop from 2500 to 1200 is going to make anyone exhausted regardless of whether they're on medication. Your body is running on significantly less fuel while your energy demands haven't changed.

That said, GLP-1 RAs can contribute to fatigue through several mechanisms:

• Altered glucose dynamics (more stable but potentially lower average glucose — your body was adapted to higher levels)
• Indirect effect of nausea and reduced food enjoyment on energy
• Possible mild dehydration (many patients drink less because they "forget")
• Disrupted sleep from GI discomfort

My recommendations:

1. Increase your caloric intake to at least 1400-1500 — you'll still lose weight but you'll function as a human being
2. Focus on protein and complex carbs for sustained energy
3. Get bloodwork: CBC, TSH, vitamin B12, iron panel, vitamin D, basic metabolic panel
4. Hydrate — aim for 80+ oz water daily
5. Don't trust the appetite suppression to guide your intake right now — it's overcorrecting

I dealt with exactly this. Month 2-3 was like wading through molasses. Turned out three things were going on simultaneously:

1. I was eating 900 calories some days (the appetite suppression made me forget meals entirely)
2. My vitamin D was 14 ng/mL (severely deficient)
3. I was dehydrated — I'd gone from drinking tons of water to barely any because I just wasn't thirsty

Once I started intentionally eating 1500 cal with protein at every meal, supplemented D3 50,000 IU weekly per my doc, and set water reminders on my phone — the fatigue improved dramatically within 2 weeks.

You have to think of food as medicine on this drug. You can't just let the appetite suppression drive the bus entirely.

Not to be that person but — are you sleeping well? Semaglutide gave me the WORST insomnia for the first month. I'd be tired all day but then lie awake at night. That sleep deprivation compounded with the caloric deficit made me a zombie.

Melatonin 3 mg and a strict sleep schedule helped. Also cutting all caffeine after noon.

following this thread closely because i start next week and i work a physically demanding job (nurse, 12-hour shifts). cannot afford to be exhausted. any tips for managing energy when you can't just "rest when tired"?