Here's an interesting article about using your sense of smell to lose weight. NOTE: it is basically an advertisement for their product so take it with a grain of salt. ;-)
And I'm not sure who they are used for their study, but most people I know who have done Weight Watchers lose more than 10lbs every 18 months! And with the Flat Belly Diet, I lost 8lbs the first month.
And, some common sense from Denise Austin:
Find the Key to Weight-Loss Success
Q: Do you recommend cutting carbs or cutting fat to lose the most weight?
A: I'm honestly more into cutting calories, because I like a well-balanced eating plan that includes such good, healthy carbs as whole grains, beans, fruits, and vegetables and about 25 percent good fats, such as lean chicken, fish, avocados, and olive oil. My Meal Plan provides you with low-calorie recipes that incorporate these recommendations.
Remember, weight loss is all about how many calories you eat versus how many you burn through daily movement and exercise!