I'm going to throw an unsolicited plug for Weight Watchers in here.

Both my kitten and I had put on some weight over the years, she started Weight Watchers in January and I participated to support her. We both lost the amounts we wanted to. kitten's now a lifetime member and gets the program free so long as she doesn't go more than two pounds over her goal weight.

The reason I plug them is because it's a rational way to weight loss. It's a not a diet, it's not a special food plan, it's a lifestyle program to learn normal, healthy eating habits with a support group structure that worked well for us. You could do the same thing by counting calories and fat yourself, but their program and tools make it easier.