Weight Watchers has revealed that the "uncertain economic environment" has caused the company's first-half revenues to fall.

In the first half of 2009, net revenues totalled US$763.1m , down from $837m in the first half of last year.

Net income rose to $106.1m, up from $104m last year when the company was hit by a VAT ruling in the UK. Income in the first six months of this year was reduced by $3.1m in after-tax restructuring charges associated with the group's cost-saving initiatives.

Earnings per fully diluted share were $1.38 for the first half of 2009 versus $1.31 a year ago.

"While we are closely managing our operations for the near-term given this uncertain economic climate, we are continuing to invest in multiple initiatives that will result in a meaningful and substantial improvement in our long-term growth trajectory," president and CEO David Kirchhoff revealed.

The company narrowed its full-year earnings guidance range from $2.50-$2.75 to $2.52-$2.70, excluding restructuring charges.