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How Long Does it Take to Form a Healthy Habit?


Updated August 22, 2013

Question: How Long Does it Take to Form a Healthy Habit?

Establishing Healthy Behaviors Might Take Longer Than You Think

Conventional wisdom tells us that it takes about four weeks to build a habit. But is that really true? If you're trying to eat more nutritiously, or live an anti-aging lifestyle generally, how long will it take for a new healthy habit to stick?


There's no doubt that establishing regular healthy habits (or breaking bad ones) can improve your longevity. Once healthy behaviors — like quitting smoking, drinking only in moderation, or getting regular exercise — are entrenched into your regular schedule, you're more likely to do them consistently.

Despite that, there's surprisingly little research on how much time is actually required to establish a new habit. University College London epidemiologist Phillippa Lally examined the habit formation process in everyday life. Her study was published in 2010 in the European Journal of Social Psychology.

How is a habit defined? Doing something for the first time takes preparation and intention. With consistency, less attention, thought, or effort must be paid. Lally describes a habit as a behavior that is repeated often enough so that over time, less conscious thought is required to make it happen. Rather, cues in a person's environment or situations begin to trigger the behavior as an automatic response: it's bedtime, so you brush your teeth (teeth-brushing has thus become a habit).

How do you know when it's become automatic? The paper cites the following characteristics of an automatic behavior or habit:

  • it's efficient
  • you're less aware that you're doing it
  • it's unintentional
  • it's less controllable

How long does it take? According to Lally's study, past research suggests that a behavior has become habitual once it has been "performed frequently (at least twice a month) and extensively (at least 10 times)". Lally's own research discovered it can take much longer than that.

Studying habit formation: A total of 82 adults were studied for a period of 12 weeks. They were asked to choose a healthy activity, drinking, or eating behavior that was not already part of their daily routine, and to perform it at a similar time or place each day. They were to identify a cue or situation that could prompt the behavior, as long as that cue happened only once daily. Each subject was to record on a website whether or not they performed the potential habit. No reward of any kind was offered as incentive for repeating the behavior.

Subjects chose actions like running 15 minutes before dinner, eating a piece of fruit with lunch, or meditating.

Time to form a habit: The median length of time it took for a habit to become automatic was 66 days. The range, however, was 18 to 254 days for the habit to be established. In fact, about half of the subjects did not perform their chosen action consistently enough to create a habit.

Interestingly, increased repetition of an action does not always yield stronger habits. Lally found that consistently repeating a behavior early in the process was more effective in creating an automatic action, than repetition later on. Further, after a certain time the habit-forming process plateaus so additional repetition does not further solidify the habit. The relationship between repetition and strength of habit is therefore not linear in this study.

What does this mean for you? Unlike the four-week time frame often cited as a threshold for establishing a habit, Lally's research suggests that many more days and weeks of diligence might be necessary. You needn't be discouraged by this finding; just recognize that behavior change is challenging, and look for ways to support your lifestyle tweaks — performing them consistently and often — to help make them permanent.


Changing Your Habits: Steps to Better Health. US Department of Health and Human Service/National Institutes of Health Public Information Sheet. Accessed August 22, 2013.

Guide to Behavior Change. US National Heart, Lung, and Blood Institute Public Information Sheet. Accessed August 22, 2013.

Phllippa Lally, Cornelia H M Van Jaarsveld, Henry W W Potts and Jane Wardle. "How are Habits Formed: Modelling Habit Formation in the Real World." European Journal of Social Psychology 40; 998-1009 (2010).

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