Alli - the mechanics of fat elimination are less than beautiful

"And what happens to the fat?" I ask.

"Well, it's naturally... it..." says the Alli rep, looking a bit uncomfortable.

"It's eliminated from the body in the usual way" I finish for her, rolling my hands and nodding complicitly. She smiles, relieved.

I'm in Boots, and I'm at the Alli promotional stand chatting to the rep there about the mechanics of the latest word in weight-loss. And we just got down to the crux of the matter.

Alli is an over-the-counter diet drug that stops some of the fat from your diet being absorbed into your body tissue. It can result in 50% extra weight-loss when combined with a recommended low-fat diet. You knew that, didn't you, because it's been marketed all over the UK with massive campaigns and in-store sales drives.

What you might not have known is that Alli is actually a weaker dose of a prescription drug, Orlistat (Xenical), that has been available from GPs as a treatment for obesity for several years.

Orlistat/Alli causes some of the fat you eat to be bypassed by the body and deposited by the digestive system - "in the usual way". It might make "the usual way" a bit
unusual, without going into details, but it should be manageable, provided you stick rigidly to your low-fat diet.

If you don't stick to your low-fat diet, you might experience some very unpleasant changes to your "usual way", including diarrhoea, uncontrollable flatulence, and in worst cases, incontinence.. Some users have even reported these horrifying effects when using Alli correctly, especially at the start of treatment. If you want more details, here's a link to Liv from greenisboring.com's account of the Alli "treatment effects" (not recommended for the squeamish).

I had another question for my rep - "Is Alli selective about the type of fats it blocks? Is it only saturated fats? What about oil-soluble vitamins, Omega 3's and the like?"

For that we had to consult the pharmacist, who advised that no, Alli is not selective. Your good fats, your bad fats - the blocking effect applies to everything fatty, so if you're taking a lipid-based supplement like Evening Primrose or Cod Liver Oil, you might well be flushing some of the beneficial effects of that down the pan too.

It's clear that Alli could help you if you're sticking religiously to a low-fat diet and want an extra helping hand to cut down the amount of fat going into your body (or a hell of a motivation not to stray from your diet). But do be aware - it's not a magic pill, and it needs serious commitment, otherwise your results could be dramatic - in all the wrong ways.

Alli is available from chemists nationwide.