Liraglutide

Structure: Acylated GLP-1 analog with 97% homology to native human GLP-1, plus a C16 fatty-acid chain that binds albumin and extends the half-life from minutes to hours.

Dosage:

• Weight management (Saxenda titration): 0.6mg/day for 1 week, increase by 0.6mg/week to 3.0mg/day
• Type 2 diabetes (Victoza): 0.6mg/day for 1 week, then 1.2mg/day, can increase to 1.8mg/day
• Bodybuilding cut (off-label): typically 1.2 to 1.8mg/day; some users only use 0.6 to 1.2mg

Administration:

• Once-daily SubQ injection at the same time each day
• Abdomen, thigh, or upper arm; rotate sites
• Pre-filled multi-dose pen with adjustable dose dial
• Titrate slowly to minimise GI side effects

Key Notes:

• The original "weight loss GLP-1". Pi-Sunyer 2015 (NEJM) showed ~8% body weight loss vs ~2.6% on placebo at 56 weeks in people with obesity.
• Cardiovascular outcomes data (LEADER trial, 2016) is robust: significant reduction in major adverse cardiovascular events in type 2 diabetics with established cardiovascular disease. This evidence base is more mature than for semaglutide or tirzepatide.
• Daily dosing is the main practical disadvantage versus weekly semaglutide and tirzepatide. Adherence is harder; a missed dose has more clinical effect proportionally.
• Generally less weight loss than semaglutide 2.4mg or tirzepatide 15mg in head-to-head trials, but more affordable and increasingly available as a generic.
• Same GI side-effect profile as the rest of the class: nausea, vomiting, diarrhoea, constipation. Mostly during titration.
• Discontinue and seek medical evaluation for severe persistent abdominal pain (pancreatitis), gallbladder symptoms, or signs of medullary thyroid carcinoma (MTC contraindication, applies to all GLP-1 agonists by class labelling).
• Bodybuilding-relevant pitfall: aggressive caloric deficit on a GLP-1 plus insufficient protein and resistance training causes meaningful muscle loss. Mitigate with >2g/kg protein and full training volume.
• Monitor: fasting glucose, HbA1c, lipid panel, amylase / lipase, eGFR / creatinine (modest renal protection in diabetes data, but volume-depleted users can develop AKI from prolonged GI losses).

References:

• Pi-Sunyer, X., Astrup, A., Fujioka, K., Greenway, F., Halpern, A., Krempf, M., Lau, D. C., le Roux, C. W., Violante Ortiz, R., Jensen, C. B., & Wilding, J. P. (2015). A randomized, controlled trial of 3.0 mg of liraglutide in weight management. New England Journal of Medicine, 373(1), 11-22. DOI: 10.1056/NEJMoa1411892
• Marso, S. P., Daniels, G. H., Brown-Frandsen, K., Kristensen, P., Mann, J. F., Nauck, M. A., Nissen, S. E., Pocock, S., Poulter, N. R., Ravn, L. S., Steinberg, W. M., Stockner, M., Zinman, B., Bergenstal, R. M., & Buse, J. B. (2016). Liraglutide and cardiovascular outcomes in type 2 diabetes (LEADER trial). New England Journal of Medicine, 375(4), 311-322. DOI: 10.1056/NEJMoa1603827
• Mehta, A., Marso, S. P., & Neeland, I. J. (2017). Liraglutide for weight management: a critical review of the evidence. Obesity Science & Practice, 3(1), 3-14. DOI: 10.1002/osp4.84