I've been on a mission since the beginning of the year to get my weight and health under control. I track the calories of everything I eat/drink plus the amount of exercise I get everyday. Then at the end of the week I add it all up and measure my progress (fat%, muscle%, etc...)
I've been able to drop 12 pounds of body fat and increase my muscle percentage over this last year, for the first time in my life, by tracking all this stuff...
It's very focused on weight. If you're not on the extreme end of being "overweight" - tracking how many pounds you weigh is not the correct approach to staying fit and trim. Instead, you need to track body fat % and muscle %.
Most people go on diets, weigh themselves, find they have lost many pounds and proclaim victory. Only later do they find that they have gained that weight back, and them some. This cycle typically continues and that person never finds success.