Why Weight Loss Happens in Waves on GLP-1 Medications

One of the biggest misconceptions about weight loss is that every pound lost represents fat. In reality, the scale reflects multiple variables:

• Fluid shifts

• Glycogen storage

• Hormonal changes

• Digestive content

• Inflammation levels

Fat loss happens gradually. The scale, however, moves based on all of these factors combined.

So when weight fluctuates, it does not automatically mean progress has stopped.

In the first few weeks of GLP-1 therapy, many people experience a rapid drop.

This is largely due to changes in insulin levels and glycogen storage.

Glycogen — the stored form of carbohydrate in the liver and muscles — holds onto water. For every gram of glycogen, the body stores approximately 3–4 grams of water.

When insulin stabilizes and appetite decreases, glycogen stores shrink. As glycogen decreases, the associated water is released.

That early drop feels exciting — but it sets unrealistic expectations for what comes next.

Because after the fluid shifts stabilize, fat loss continues at a slower, more steady pace.

Even after the initial phase, glycogen continues to fluctuate.

A higher carbohydrate meal, increased sodium intake, stress, or poor sleep can increase water retention. That can temporarily increase scale weight — even if fat loss is ongoing.

This is why many patients see:

• A week with no movement

• A slight gain

• Then a sudden drop

The body is not regaining fat overnight. It’s managing water.

For many women, hormonal fluctuations significantly influence scale patterns.

Estrogen and progesterone shifts can:

• Increase fluid retention

• Slow digestion

• Increase perceived bloating

This often creates what feels like a “plateau,” especially in the week before menstruation.

However, when hormone levels shift again, the retained fluid releases — and the scale drops.

Without understanding this cycle, it’s easy to assume the medication has stopped workin

Many patients describe a pattern:

Two to three weeks of minimal change — followed by a sudden drop of two to four pounds.

This is commonly called the “whoosh effect.”

While not formally defined in medical literature, a plausible explanation is that as fat cells shrink, temporary water retention fills the space. Once the body releases that retained fluid, the scale drops quickly.

In other words, stalls often precede visible progress.

Fat loss is not a daily event. It is a metabolic remodeling process.

GLP-1 medications work by:

• Improving insulin sensitivity

• Reducing appetite signaling

• Slowing gastric emptying

• Stabilizing blood sugar

These changes support gradual fat loss — but they do not override normal fluid physiology.

Escalating doses too quickly because of a temporary stall can increase side effects without improving outcomes.

Consistency, not panic, produces long-term results.

Weight loss on GLP-1s should be evaluated over 4–6 week trends — not daily numbers.

When progress slows, ask:

• Has appetite control improved?

• Are portions naturally smaller?

• Is energy more stable?

• Are cravings quieter?

These markers often improve before the scale reflects fat loss.

Understanding that weight loss happens in waves reduces anxiety, improves adherence, and prevents unnecessary discontinuation.

And adherence is what creates sustainable metabolic change.