If you are already at the weight to which you normally gravitate, then I would say "no," definitely not in the long-term. I know that for me (I'm 5'7, 122-23), when I'm training seriously (60+ miles / week including quality workouts), I would have to basically not eat anything (or less than 1200 calories / day) to get down to 119 / 120, or alternately, I would have to consistently increase my caloric intake by about 1000 calories / day to get to 128-29. If you have to drastically reduce calorie consumption to get to 120, then I'd say that it won't help you, performace-wise. If, on the other hand, cutting out one snack gets you there, then who knows.