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The Science

Interactive mechanism map

A body map of fifteen organs and brain regions. Select one to see each documented effect of GLP-1 receptor agonists, GIP/GLP-1 dual agonists, GIP alone or the native hormones, graded A to D by the kind of evidence behind it, each with a PubMed id or FDA label citation. Debated mechanisms are flagged, not hidden.

By FormBlends editorial teamAssumptions checked September 4, 2026Runs in your browser; nothing is sent to a server

Effects shown for this filter: 14 grade A, 14 grade B, 6 grade C, 5 grade D. Click a node on the map or in the list.

Body map

Interactive body map of GLP-1 and GIP receptor effectsA stylised human outline with fifteen labelled nodes: reward circuits, hypothalamus, brainstem, upper airway, thyroid C cells, heart, liver, stomach, gallbladder, pancreatic beta and alpha cells, adipose tissue, kidney, intestine and skeletal muscle. Each node is coloured by the strongest evidence grade behind its effects. Selecting a node shows its effects and citations beside the map.HypothalamusBrainstem (area postrema, NTS)Reward circuitsIntestine (L and K cells)StomachPancreatic beta cellsPancreatic alpha cellsLiverAdipose tissueSkeletal muscleHeartKidneyUpper airway (sleep apnea)Thyroid C cellsGallbladderColour = strongest evidence grade at that node.Dashed line = debated or animal-only.
Brain:
Gut:
Pancreas:
Metabolic organs:
Heart and vessels:
Kidney:
Other:

Effects: Hypothalamus

Arcuate nucleus neurons carry GLP-1 receptors and sit outside the blood-brain barrier, so a circulating drug can reach them.

  1. C

    Liraglutide reaches the arcuate nucleus and activates POMC/CART neurons; weight loss depends on that region in mice.

    GLP-1 RA

    Secher A et al. J Clin Invest 2014. PubMed 25202980
  2. B

    Semaglutide reduced ad libitum energy intake by about 24% versus placebo in adults with obesity, with lower hunger and fewer cravings.

    GLP-1 RA

    Blundell J et al. Diabetes Obes Metab 2017. PubMed 28266779
  3. D

    GIP receptor cells in the hypothalamus also regulate food intake in mice; whether GIP agonism or antagonism is the better route in humans is unresolved.

    GIP, GIP/GLP-1 RAdebated

    Adriaenssens AE et al. Cell Metab 2019. PubMed 31447324

Read the full explainer for this node

A
Randomised human outcome or phase 3 trial, or an FDA label statement derived from one
B
Human physiology, imaging, pharmacokinetic or large cohort study
C
Animal or cell evidence only
D
Hypothesis or actively debated
Formulashown in full, nothing hidden
grade(effect) = A if from a randomised human outcome or phase 3 trial, or an FDA label statement derived from one
             = B if from a human physiology, imaging, pharmacokinetic or large cohort study
             = C if from animal or cell evidence only
             = D if a hypothesis, or actively debated in the literature
node colour   = strongest grade among the effects shown for the current filter
dashed leader = the node's best grade is D

A grade describes the kind of evidence, not the size or certainty of the effect. A grade A adverse-reaction rate and a grade A outcome trial are both randomised evidence, but they answer different questions. One citation is attached to each effect; the explainer pages carry the fuller reference lists.

Assumptions, checked September 4, 2026

  • Effects and grades were assigned by the FormBlends editorial team from the cited paper or label; they are an editorial reading, not a systematic review.
  • Label statements are taken from the current Wegovy and Zepbound prescribing information on Drugs@FDA.
  • Animal findings (grade C) are shown because they explain mechanisms, not because they predict human effects.
  • Compounded GLP-1 products are not FDA approved and are not covered by these labels or trials.

This calculator is an arithmetic aid for medication a licensed prescriber has already prescribed. It does not recommend a dose. Confirm any result with your prescriber or pharmacist before use.

Sources

  1. Secher A et al. J Clin Invest 2014. PubMed 25202980
  2. Blundell J et al. Diabetes Obes Metab 2017. PubMed 28266779
  3. Adriaenssens AE et al. Cell Metab 2019. PubMed 31447324
  4. Huang KP et al. Nature 2024. PubMed 38987598
  5. Wegovy (semaglutide) prescribing information, FDA label
  6. Borner T et al. Diabetes 2021. PubMed 34380697
  7. van Bloemendaal L et al. Diabetes 2014. PubMed 25071023
  8. Nauck MA et al. J Clin Endocrinol Metab 1986. PubMed 3514343
  9. Deacon CF et al. Diabetes 1995. PubMed 7657039
  10. Nauck MA et al. Diabetes 2011. PubMed 21430088
  11. Urva S et al. Diabetes Obes Metab 2020. PubMed 32519795
  12. Zepbound (tirzepatide) prescribing information, FDA label
  13. Nauck MA et al. J Clin Invest 1993. PubMed 8423228
  14. Holz GG et al. Nature 1993. PubMed 8381210
  15. Willard FS et al. JCI Insight 2020. PubMed 32730231
  16. Nauck MA et al. J Clin Endocrinol Metab 2002. PubMed 11889194
  17. Campbell JE, Drucker DJ. Cell Metab 2013. PubMed 23684623
  18. Pyke C et al. Endocrinology 2014. PubMed 24467746
  19. Newsome PN et al. N Engl J Med 2021. PubMed 33185364
  20. Gastaldelli A et al. Lancet Diabetes Endocrinol 2022. PubMed 35468325
  21. Jastreboff AM et al. N Engl J Med 2022. PubMed 35658024
  22. Samms RJ et al. Trends Endocrinol Metab 2020. PubMed 32396843
  23. Wilding JPH et al. N Engl J Med 2021. PubMed 33567185
  24. Villareal DT et al. N Engl J Med 2017. PubMed 28514618
  25. Lincoff AM et al. N Engl J Med 2023. PubMed 37952131
  26. Kosiborod MN et al. N Engl J Med 2023. PubMed 37622681
  27. Drucker DJ. Cell Metab 2016. PubMed 27423522
  28. Perkovic V et al. N Engl J Med 2024. PubMed 38785209
  29. Gutzwiller JP et al. J Clin Endocrinol Metab 2004. PubMed 15181026
  30. Hammoud R, Drucker DJ. Nat Rev Endocrinol 2023. PubMed 36509857
  31. Malhotra A et al. N Engl J Med 2024. PubMed 38912654
  32. Schwartz AR et al. Proc Am Thorac Soc 2008. PubMed 18250211
  33. Bjerre Knudsen L et al. Endocrinology 2010. PubMed 20203154
  34. Hegedüs L et al. J Clin Endocrinol Metab 2011. PubMed 21209033
  35. Pasternak B et al. BMJ 2024. PubMed 38626916

Educational, not medical advice. Read the medical disclaimer.