The Science · FormBlends network
Understand what a GLP-1 does inside your body, in plain English.
Fourteen mechanisms drawn as diagrams: where the hormones come from, what they do to your stomach, your appetite and your blood sugar, and why weight returns when you stop.
- 14
- mechanisms, each with an original diagram
- Each mechanism gets its own diagram, drawn from the cited papers.
- About 24%
- less energy eaten at a test lunch after 12 weeks of semaglutide
- How much less people ate at a test meal after 12 weeks of semaglutide. Appetite is the main effect.
- 1 to 4 bpm
- mean resting heart-rate rise on semaglutide
- The average resting heart-rate rise on semaglutide. Small, real, and on the label.
Start here
Three ways in, depending on what you need right now
- 01Interactive mechanism mapClick an organ, see what GLP-1 and GIP receptor activation does there, with an evidence grade and citation.
- 02Incretin physiology: where GLP-1 and GIP come from and what they hitYour gut makes two hormones after a meal, GLP-1 and GIP, and every GLP-1 drug copies one of them.
- 03Browse mechanisms14 pages, most recently updated September 4, 2026
Interactive
The calculator
Each runs in your browser, shows its formula, and prints a dated assumptions note. Nothing you type leaves the page.
Reading
Start with these
Each page opens with a plain-English summary, a figure drawn from the data, the numbers that matter, and what it means if you're considering treatment.
Mechanisms
Incretin physiology: where GLP-1 and GIP come from and what they hit
You'll get: Your gut makes two hormones after a meal, GLP-1 and GIP, and every GLP-1 drug copies one of them.
The two gut hormones behind every GLP-1 medicine: which cells release them, how fast the body destroys them, and the organs they act on. Drawn from the primary physiology papers.
Mechanisms
GLP-1 receptor effects by organ: direct, indirect and absent
You'll get: A drug can only act directly on tissue that has its receptor, the lock the drug fits.
Which body tissues have the GLP-1 receptor and which do not, and why that decides whether an effect on the heart, liver or kidney is direct or indirect.
Mechanisms
The GIP receptor and why dual agonism is not just more GLP-1
You'll get: Tirzepatide acts on two gut hormone signals, GIP and GLP-1, while semaglutide acts on one.
What the gut hormone GIP does, why tirzepatide hits two hormone signals instead of one, and why scientists still argue about how that extra signal helps.
Mechanisms
Gastric emptying and tachyphylaxis: why the slowing fades
You'll get: These drugs slow how fast food leaves your stomach, most of all in the first weeks.
How GLP-1 drugs slow the stomach, why that effect is biggest after the first dose and fades within weeks, and what it means for pills and surgery.
Mechanisms
Appetite circuits: hypothalamus, brainstem and reward
You'll get: These drugs help you lose weight mainly by making you eat less.
Where in the brain GLP-1 drugs act to cut hunger and eating, what human studies measured, and which parts are still only shown in animals.
Live updates
What changed since this site was written
Sources checked October 19, 2026, refreshed every six hours.
Newest on PubMed
Papers indexed in the last year matching incretin mechanisms (1,635 in total).
- Tolerability language and gastrointestinal risk in a meta-analysis of GLP-1 receptor agonists in antipsychotic-treated schizophrenia
Schizophr Res · October 18, 2026 · PubMed 42893627
- GLP-1 receptor agonist therapy and incident atrial fibrillation in non-diabetic adults with obesity and chronic kidney disease: a propensity matched cohort study
Int J Cardiol · October 17, 2026 · PubMed 42892471
- GLP-1 receptor agonists in psychiatry: from metabolic care to psychiatric evidence
Eur Arch Psychiatry Clin Neurosci · October 17, 2026 · PubMed 42888290
- GLP-1 receptor agonists in Alzheimer's disease and MCI: a meta-analysis
Alzheimers Dement (N Y) · October 15, 2026 · PubMed 42890838
- Energy-Based Devices for GLP-1 Receptor Agonist-Associated Facial Aging: A Tissue-Specific Safety Framework
Clin Cosmet Investig Dermatol · October 12, 2026 · PubMed 42893183
FDA and enforcement tracker
FormBlends research feed, data as of September 4, 2026.
September 1, 2026 · Adverse-event report update
FDA GLP-1 concerns page updated: 990 adverse-event reports for compounded semaglutide and >730 for compounded tirzepatide (as of May 31, 2026); border screening and fake-pharmacy labelsAugust 28, 2026 · Label or price event
FDA approves Mounjaro (tirzepatide) to reduce MACE risk in adults with type 2 diabetes (SURPASS-CVOT)August 27, 2026 · Court decision
Fifth Circuit affirms summary judgment for FDA in both GLP-1 shortage cases (Nos. 25-10600 tirzepatide; 25-10758 semaglutide)August 24, 2026 · FDA warning letter
FDA warning letters to five peptide vendors: Peak Performance Peptides (735127), Royal Peptides (734884), NuScience Peptides (733652), Peptide Partners (735063), TXP Innovations dba Tex Peptides (735067)August 24, 2026 · FDA warning letter
FDA warning letter: TXP Innovations LLC dba Tex Peptides (Unapproved New Drugs/Misbranded)
Compounded price index
Median all-in cash price per 28 days across providers, as of September 3, 2026.
- semaglutide, month 1 at 0.25 mg/week
- $197
- median of 14 providers
- semaglutide, month 4 at 1 mg/week
- $199
- median of 13 providers
- tirzepatide, month 1 at 2.5 mg/week
- $268
- median of 14 providers
- tirzepatide, month 4 at 5 mg/week
- $299
- median of 12 providers
- September 3, 2026: Index, All, baseline 51 rows. First weekly snapshot. Changes against this baseline will be listed here with the date they were observed.
PubMed lists come from NCBI E-utilities and are not reviewed by us before they appear. Feeds are FormBlends Research data (CC BY 4.0); FormBlends sells compounded GLP-1 drugs and appears in the price index under the same rules as every other provider. Compounded drugs are not FDA approved.
Browse
Sections
18 pages across 2 sections, each sourced to a label, a trial or a dated manufacturer page.
Mechanisms
You'll get: 14 sourced pages, each with a plain-English opener
The two gut hormones behind every GLP-1 medicine: which cells release them, how fast the body destroys them,...
Outcomes
You'll get: 4 sourced pages, each with a plain-English opener
What the SELECT trial found: 20 percent fewer heart attacks, strokes and heart deaths on semaglutide, and...
How the diagrams are made
Every figure is an original SVG drawn for this site from the cited papers and labels, not a redrawn textbook figure. Each carries a title and a description for screen readers. Arrows mean a documented effect; a dashed arrow means the effect is debated or shown only in animals. The mechanism map grades each effect A to D by the kind of evidence behind it.
What this site is not
These pages are educational. They do not tell you whether a medicine suits you, what dose to take or when to stop. Compounded GLP-1 products are not FDA approved and are not interchangeable with brand products; where a page mentions them it says so. Talk to a licensed prescriber about anything that applies to you.