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ForumsDosing & ProtocolsNeedle length selection — 4mm vs 6mm vs 8mm by BMI and site

Needle length selection — 4mm vs 6mm vs 8mm by BMI and site

JennaRN Sat, May 30, 2026 at 11:17 PM 7 replies 298 viewsPage 1 of 2
JennaRN
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May 30, 2026 at 11:17 PM#1

Collecting this in one place because it comes up every few weeks and the answer is always assembled from scratch. It is about the titration schedule, and it is deliberately narrow — everything I am not confident about is marked as such.

What is actually established

Holding longer is the underrated move. A step that is uncomfortable at week two is frequently comfortable at week six with no change in dose, because the gastric-emptying component tachyphylaxes while the appetite effect persists. Escalating at week two throws that adaptation away.

The condition it depends on

One condition: holding indefinitely at a dose that is not doing anything is not patience, it is a stall with a nice name. The distinction is whether appetite has changed at all at the current step.

The practical version

The arithmetic in one line: half-life about a week, so steady state at four to five weeks, so a four-week interval is one steady state per step. Two-week intervals mean every step is dosed onto a rising curve.

What I am not sure about

The question I want answered is why the interval is four weeks rather than two, and whether a slower ladder gets to the same place. Not looking for reassurance. Looking for the part I have got wrong.

— JennaRN · corrections welcome and will be edited into this post with credit
30 0Dr.KarenChen, Dr.NateNeph, PharmD_Rodriguez and 27 others
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RetaRick_CA
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May 30, 2026 at 11:54 PM#2
JennaRN said:
A step that is uncomfortable at week two is frequently comfortable at week six with no change in dose, because the gastric-emptying component…

That is correct as far as it goes, and here is where it stops going. The trials generally allowed a step to be held or reduced and then retried, and people who did that mostly arrived at the same place a few weeks later. The end point of the ladder is set by tolerability, not by a schedule, and there is no evidence that reaching the top faster produces a better outcome.

29 24AmyNC_wife, SkepticalSean, Dr.CardioMD and 26 others
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Dr.SportsMedIN
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May 31, 2026 at 12:31 AM#3
JennaRN said:
A step that is uncomfortable at week two is frequently comfortable at week six with no change in dose, because the gastric-emptying component…

I disagree that the ladder is purely tolerability. The maintenance and regain data cluster at the top doses, so a ladder abandoned halfway leaves you outside the evidence base for the part that matters most — keeping it off.

28 23adam_van, Dr.SurgeonPGH, rachel_ABQ and 25 others
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PeptideChemSF
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May 31, 2026 at 1:08 AM#4

Short answer first, then the reasoning. Four weeks is the pharmacokinetics, not caution. With a one-week half-life you need four to five half-lives to reach steady state, so at two weeks you are dosing on top of a concentration that has not finished rising. Escalating then stacks exposure and you get the side-effect burden of the higher dose before you have seen the benefit of the current one.

27 22ricardo_MIA, BrianDallas92, labquiet_amy and 24 others
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NurseLeah_Nash
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May 31, 2026 at 4:35 AM#5
RetaRick_CA said:
The trials generally allowed a step to be held or reduced and then retried, and people who did that mostly arrived at the same place a few weeks…

Second this.

Last edited: May 31, 2026 at 5:35 AM
26 21Dr.NateNeph, PharmD_Rodriguez, julia.endo and 23 others
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