February 3, 2010 — A randomized placebo controlled trial of orlistat (Alli, GlaxoSmithKline) 60 mg daily for overweight to obese but otherwise healthy subjects showed that the weight-loss agent was not only associated with greater overall weight loss than placebo, but that there was a greater loss of visceral fat with active treatment.
Furthermore, effects were seen within 3 months, investigator Rex Newbould, PhD, head of the Clinical Imaging Center at Hammersmith Hospital in London, United Kingdom, reported at the first International Congress on Abdominal Obesity (ICAO) underway in Hong Kong.
Of the 26 overweight and obese subjects (body mass index [BMI], 25.0 to 35.0 kg/m2; waist circumference >88 cm for women and >102 cm for men) enrolled, 24 completed the 12-week study.
Subjects took orlistat 60 mg 3 times a day and ate a hypocaloric (reduced by 500 kcal) low-fat diet. Subjects received a single dietary counseling session, and an abdominal magnetic resonance imaging (MRI) scan was performed to measure visceral adipose tissue (VAT) at baseline. Body weight and waist circumference were measured at weeks 4, 8, and 12, and a repeat abdominal MRI scan was performed at week 12.
After 12 weeks, orlistat was associated with a significant reduction in body weight, waist circumference, and VAT, according to MRI.
"MRI measures fat more accurately than weight or waist measurement," Dr. Newbould told Medscape Medical News. "It measures the fat inside the fat, and has less 'noise' than other measurements. It measures only fat, whereas weight is a measure of fat, fluid, and other factors."
The change in VAT was correlated with the change in weight (P < .0001) but not waist circumference (P = .35). The mean change in weight was –5.24 kg (–5.6%), in waist circumference was –4.54 cm (–4.3%), and in VAT was –0.60 L (–10.6%).
"Visceral fat is the metabolically active type of fat that is associated with adverse outcomes," Dr. Newbould explained. "We would expect [a loss of VAT] to be associated with improved outcomes."
A similar study was presented by Kaj Stenlöf, MD, executive director of the Clinical Trial Center at Sahlgrenska Academy in Göteborg, Sweden.
He and his colleagues randomized 131 overweight and obese subjects (BMI, 25 to 35 kg/m2; waist circumference >88 cm for women and >102 cm for men) to orlistat 60 mg or placebo 3 times a day plus a hypocaloric low-fat diet for 24 weeks. Subjects were "encouraged to exercise," but were not on a prescribed exercise regimen.
Treatment was well tolerated, Dr. Stenlöf said, and 107 subjects completed the study. The primary adverse effects were gastrointestinal.
Mean change in VAT after 24 weeks of orlistat treatment was –9.39% in the placebo group (P < .0001) and –15.66% in the orlistat group (P < .0001). The percent change difference from baseline to week 24 between the placebo and orlistat groups was 0.227 (P < .0244).
In addition, there was a significant reduction in mean body weight from baseline to week 24 in both groups, with a loss of 5.96 kg in the orlistat group and 3.91 kg in the placebo group (P < .05).
Although only data on VAT were presented at the meeting, Dr. Stenlöf told Medscape Medical News that they are calculating cardiac muscle fat and fat in other muscles, and are computing other parameters, such as blood pressure and blood glucose. These data will be presented this summer at the International Conference on Obesity in Stockholm, Sweden.
"With the over-the-counter formulation of orlistat, there has been a conceptual shift in the treatment of obesity," Jean-Pierre Després, PhD, director of research in cardiology at the Quebec Heart and Lung Institute at Laval University in Quebec City, told Medscape Medical News.
"Instead of overall weight loss, we are now focusing on this high-risk form of obesity, with loss of the more metabolically active visceral fat — the fat that carries a high risk of heart disease."
"We don't know if orlistat induces a preferential loss of visceral fat. Those data are just now coming in, and we heard some new data here," said Dr. Després, who is chair of the ICAO. "We don't know if the loss of visceral fat is part of overall weight loss. The key point is that there has been a paradigm shift to focus on the reduction of this most dangerous form of obesity."
"Orlistat is very safe and is an effective therapy in motivated patients," said Christie M. Ballantyne, MD, professor of medicine at Baylor College of Medicine and director of the Center for Cardiovascular Disease Prevention at Methodist DeBakey Heart Center in Houston, Texas, in an interview with Medscape Medical News. He was not involved in either study.
"I think it has been underutilized because of [gastrointestinal] side effects, but the data are very clear that this provides additional weight loss to a program of lifestyle modification. It has clearly been shown to have favorable effects on metabolism, and the newer data on visceral fat are also encouraging."
"This therapy should be discussed as an option, particularly in patients with comorbidities, because both the efficacy and safety are proven," Dr. Ballantyne asserted.
Both studies were supported by grants from GlaxoSmithKline. Dr. Després has disclosed no relevant financial relationships. Dr. Ballantyne reports being a consultant to GlaxoSmithKline for lipid reduction (Lovaza) and to other companies in field of lipid research, including Merck, AstraZeneca, and Abbott.
First International Congress on Abdominal Obesity (ICAO). Presented January 28, 2010.
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