The science is public.
Most apps ignore it.

Semaglutide and tirzepatide both produce large weight losses — but a meaningful portion of that weight is lean mass, not fat. In the STEP 1 trial of semaglutide, lean mass accounted for roughly 40% of total weight lost in the subset scanned by DXA. Wilding et al., NEJM 2021. In the SURMOUNT trials of tirzepatide, a similar pattern held. Jastreboff et al., NEJM 2022.

The mechanism is straightforward: GLP-1s reduce appetite, which reduces calorie intake, which — without adequate protein and resistance training — reduces both fat and muscle. A meta-analysis of weight-loss studies in older adults found that higher protein intake during caloric deficit preserves significantly more lean mass. Kim et al., Obesity Reviews 2016.

Gastric emptying slows naturally in the luteal phase of the menstrual cycle — the two weeks between ovulation and your period. Gill et al., Gut 1987. GLP-1s slow gastric emptying further. For many women, this stacking explains why nausea, early fullness, and reflux worsen in the back half of their cycle.

Beyond gastric emptying, progesterone-dominant phases are associated with fluid retention, increased appetite (particularly for carbohydrate-dense foods), and changes in sleep — all of which interact with how a GLP-1 “feels” that week. The research here is thinner than the STEP trials, and we are honest about that gap. What exists is suggestive enough to design around, not conclusive enough to guarantee.

The labeled titration schedules for semaglutide and tirzepatide exist for a reason: the longer you spend adapting to each dose, the fewer gastrointestinal side effects you are likely to carry into the next one. Wegovy PI, Zepbound PI.

Practical evidence and clinical guidance converge on a short list of things that help:

• Small, frequent meals rather than three large ones.
• Protein and fiber first, refined carbs last.
• Hydration — sparkling water, broth, electrolytes if nausea is heavy.
• Ginger for nausea — multiple RCTs in chemotherapy and pregnancy populations have shown modest but real benefit. Lete & Allúe, 2016.
• Staying at a tolerated dose longer before uptitrating.

GLP-1 weight loss is not linear. Most people see rapid loss in months 1–3, steady loss in months 4–9, and a plateau as the body reaches a new setpoint — often somewhere between 12 and 20 percent of starting weight, depending on the medication, the dose, and the individual. STEP 5: Garvey et al., 2022, SURMOUNT-4: Aronne et al., 2024.

Plateaus are physiology, not failure. They are what maintenance looks like. A plateau does not mean the medication has stopped working — it means it has worked enough to move your body to a new equilibrium.

Stopping the medication tends to reverse a portion of the loss; ongoing therapy tends to hold it. The long-term question is not whether GLP-1s “work” — the evidence is clear they do — but how your prescriber thinks about dose, duration, and taper for your specific situation.