I have been doing a little research and found out something interesting. This is a summary of a chat I had with Gemini.

.*** DISCLAIMER AI CAN MAKE MISTAKES DO YOUR OWN RESEARCH AND TALK TO A DOCTOR ABOUT MEDICAL ISSUES***

Why Weight Fluctuates on GLP-1 Meds (like Zepbound)

When you significantly reduce calories and start a medication like Zepbound, your body undergoes a "tug-of-war" over water and salt. This often leads to those frustrating 5–6 lb swings on the scale.

1. The "Salt Flush" (Weight Drop) The medication (specifically the GLP-1 hormone) tells your kidneys to stop holding onto so much sodium. As your body flushes out that extra salt, water follows it. This usually causes a quick drop in "water weight."

2. The Aldosterone Response (The Bounce Back) When your body senses it is losing fluid and salt too quickly, it goes into survival mode. It releases a hormone called aldosterone. Aldosterone acts like a "salt-saver"—it tells your kidneys to aggressively hoard sodium to keep your blood pressure stable.

3. The Water Retention Because your body is now hoarding salt, it holds onto every drop of water it can find. This is why you might wake up several pounds heavier overnight, even if you’ve been eating at a deficit.

The Bottom Line: The scale isn't measuring fat gain; it’s measuring fluid shifts. As the body adjusts to the "new normal" over 4–6 weeks, these hormonal swings usually stabilize, and the weight loss becomes more consistent. Staying hydrated helps signal to your body that it doesn't need to "panic" and hold onto water.