Break Bad Habits by Keeping Your Plan Simple

The idea of the if-then plan is that you identify a habit's triggers (the "if") and then come up with a new reaction to the trigger (the "then"). For example, if a situation arises where you'd normally buy a candy bar, you have a banana instead. Over time, this replaces the bad habit with a good one. The problem is that we tend to do this with multiple triggers and multiple plans. So, instead of just creating a plan for snacking in general, we create a plan for each snack. This isn't effective:

The take-home result? The women in the single if-then plan condition and those in the control condition showed a reduction in their snacking from baseline to follow-up (2.01 to 1.47 average daily snacks, and 2.45 snacks to 1.45, respectively). By contrast, the women in the multiple if-then plan group showed no significant reduction in snacking (1.95 daily snacks at baseline vs. 1.83 at follow-up)...

"Although multiple plans for the target behaviour should intuitively provide people with more opportunities to successfully act upon one's intentions, the present findings show, both with behavioural and cognitive measures, that formulating multiple implementation intentions is ineffective when fighting unhealthy snacking habits," the researchers said.

Basically, if you're trying to create a good habit, stick with one if-then plan per goal. If you don't, you'll likely just end up confused and won't actually form that new, healthier habit.