[2026 update] People with a low starting BMI: where the evidence stops

People with a low starting BMI: where the evidence stops Writing it up because I had to work it out twice and would rather nobody else did.

Asking about a population rather than about a person.

The published trials in this class mostly enrolled a fairly specific group, and the questions here frequently come from people well outside it. I would like to understand what the honest position is when someone falls outside the studied population: not "it is fine" and not "there is no data", but what the reasoning actually looks like.

Pancreatitis history: the compounds can rarely trigger pancreatitis. A history of pancreatitis makes monitoring for recurrence more important during titration.

I read the opening post twice before replying, because I had assumed the opposite.

Adolescents: a distinct evidence base exists. The compounds are not approved for routine adolescent obesity but are being studied. Adolescent physiology and psychology differ from adults' in ways that matter for this medication class.

Pregnancy and planning: these compounds are not approved for use in pregnancy. Planning windows (how long to wait before attempting pregnancy) are not formally established. Conservative approaches wait several months to allow clearance.

Hypoglycemia risk: in people already on insulin or sulfonylureas, adding a GLP-1 agonist requires insulin dose reduction and close monitoring for hypoglycemia. This is manageable with attention.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

Coming back to post #5, because the follow-up matters more than the original answer.

Gastroparesis: pre-existing severe delayed gastric emptying can worsen with compounds that slow it further. Discussion with a clinician is prudent if this history exists.

Picking up post #5: that is the part I would want checked first.

Medullary thyroid carcinoma history: an absolute contraindication because of the preclinical findings in rodent toxicology. The history (personal or family, especially multiple endocrine neoplasia type 2) is an important screening question.

Worth separating two things that post #5 runs together.

Renal impairment: the compounds are cleared renally to some degree. Dose adjustments might be needed in severe renal impairment. Consulting with a clinician familiar with renal dosing is prudent.

Hepatic impairment: less is known about dosing in significant liver disease than in kidney disease. Extreme caution applies because the liver metabolises a large fraction of many medications.

Disordered eating history: a history of anorexia nervosa, bulimia, or other eating disorders changes the risk-benefit calculation because appetite suppression might trigger relapse. This population requires specialist input.

Hepatic impairment: less is known about dosing in significant liver disease than in kidney disease. Extreme caution applies because the liver metabolises a large fraction of many medications.

Picking up post #10: that is the part I would want checked first.

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

Coming back to post #12, because the follow-up matters more than the original answer.

Adolescents: a distinct evidence base exists. The compounds are not approved for routine adolescent obesity but are being studied. Adolescent physiology and psychology differ from adults' in ways that matter for this medication class.