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Int J Obes Relat Metab Disord. 2000 Mar;24(3):306-13.

One-year treatment of obesity: a randomized, double-blind, placebo-controlled, multicentre study of orlistat, a gastrointestinal lipase inhibitor.

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Centre for Obesity Research, Luton and Dunstable Hospital, UK.



To assess the efficacy and tolerability of orlistat (Xenical) in producing and maintaining weight loss over a 12-month period.


Patients were randomized to double-blind treatment with either orlistat 120 mg or placebo three times daily, in conjunction with a low-energy diet, for 12 months.


Five centres in the UK.


228 obese adult patients with body mass index between 30 and 43 kg/m2 and mean weight 97 kg (range 74-144 kg).


All patients were prescribed a low-energy diet, providing 30% of energy from fat, designed to produce an individually tailored energy deficit of approximately 600 kcal/day, for a run-in period of 4 weeks and then 12 months, plus orlistat 120 mg or placebo three times daily.


Change in body weight (the primary efficacy parameter), waist circumference and adverse events were reviewed regularly, together with serum lipids, insulin, glucose and plasma levels of fat-soluble vitamins and beta carotene.


Based on an intent-to-treat analysis, after 1 y of treatment patients receiving orlistat had lost an average of 8.5% of their initial body weight compared with 5.4% for placebo-treated patients; 35% of the orlistat group lost at least 5% of body weight compared with 21% of the placebo group (P < 0.05), and 28% and 17%, respectively (P = 0.04) lost at least 10% of body weight. Orlistat-treated patients showed significant decreases (P < 0.05) in serum levels of total cholesterol, low density lipoprotein cholesterol, and in the low density lipoprotein: high density lipoprotein ratio in comparison with placebo. Both groups had similar adverse-event profiles, except for gastrointestinal events, which were 26% more frequent in the orlistat group but were mostly mild and transient. To maintain normal plasma levels of fat-soluble vitamins, supplements of vitamins A, D and E were given to 1.8%, 8.0% and 3.6%, respectively, of orlistat-treated patients, compared with 0.9% of placebo-treated patients for each vitamin type. After 1 y, the decrease in vitamin E and beta carotene was significantly greater in orlistat-treated patients compared with those receiving placebo (P < 0.001). No significant change was found in the mean vitamin E:total cholesterol ratio in either group after 52 weeks.


Orlistat, in conjunction with a low-energy diet, produced greater and more frequent significant weight loss than placebo during 1 y of treatment. One-third of orlistat-treated patients achieved clinically relevant weight loss (> or = 5% initial body weight). There was also an improvement in relevant serum lipid parameters. Fat-soluble vitamin supplements may be required during chronic therapy. Orlistat was well tolerated and offers a promising new approach to the long-term management of obesity.

[Indexed for MEDLINE]

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