How it works: Lipase inhibitor blocks fat absorption

Effect: An average of 8.6% body weight in 12 months*

Prices from:£249.00 / month


*Based on weight loss in orlistat-treated patients after 1 year. Rössner, S., Sjöström, L., Noack, R., Meinders, A.E., Noseda, G. and (2000), Weight Loss, Weight Maintenance, and Improved Cardiovascular Risk Factors after 2 Years Treatment with Orlistat for Obesity. Obesity Research, 8: 49-61.”

How Alli works for weight loss

Alli works by blocking certain enzymes in your gut, reducing fat absorption by about 25%*. This leads to weight loss as less dietary fat is absorbed by your body. It's most effective when combined with a balanced diet rich in fruits and vegetables, where about 30% of calories come from fat.

* Alli Homepage for HealthCare Professionals, GlaxoSmithKline. Accessed Jan 2024

What are the side effects of Alli?

Common gastrointestinal side effects include:

  • Oily spotting on underclothes

  • Gas with discharge

  • Urgent or increased bowel movements

  • Fatty, oily stools

  • Stomach pain

  • Faecal incontinence

Other possible effects:

  • Headaches, fatigue, anxiety

  • Respiratory or urinary infections

  • Menstrual irregularities, dental problems

  • Low blood sugar (in type 2 diabetes)


Effective treatments for weight loss

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Weight Loss Support

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Weight loss: what you need to know

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