The idea that habits form in 21 days is a myth.
How Long Does It Take to Form Healthy Habits?
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
We may make hundreds of food decisions every day, yet the vast majority pass under our conscious radar. They happen more automatically, without conscious reflection, deliberation or even awareness. We may be able to take advantage of this mindless eating, though, by harnessing the power of habit formation.
It’s been said that “Most of the time, what we do is what we do most of the time.” Many of our eating habits are indeed just that, habitual. And the busier and more distracted we are, the more likely we are to fall back on habits. That’s what they’re there for. They’re like reflexive subroutines your body uses to free up mental resources. That can work against us, in the case of bad habits, or for us, in the case of good. Imagine if you had to add “buckle seatbelt” to your to-do list every day? If you’re in the habit of buckling up, your hand will start reaching for it without you even knowing.
Once you do something long enough, it worms its way into your brain. Your brain commits the actions to memory, and can whip them out when needed to automate away some of your cognitive workload—essentially becoming second nature. The repetition of a simple action in a consistent context leads to the action being triggered when exposed to that same situation. So, do it enough times and the contextual clue—for example, getting in a car, can automatically lead to the action, reaching for the seatbelt.
Habits are defined as “learned behavioral responses to situational cues.” So, it has two parts, the cue and the action. The cue can be any context. It can be an event or a time, a location, or even a mood, as long as it’s something frequently and consistently encountered in daily life. Do something over and over again in the same context—intentionally or unintentionally—and a habit can form.
How long does it take? You may have heard that habits take 21 days to form. That’s apparently a myth that originated from anecdotal evidence of how long it takes plastic surgery patients to psychologically adapt to their new appearance. If instead habit formation is actually put to the test, the average time for that habit to become automatic is 66 days. Study volunteers were asked to choose an eating, drinking, or activity behavior to carry out daily in the same context. Examples chosen include “eating a piece of fruit with lunch,” “drinking a bottle of water with lunch,” and “running for 15 minutes before dinner.” There was considerable variation in the time it took for these actions to become automatic, from 18 to 284 days, with an average of 66. About two months seems to be what it takes across all sorts of habits. The researchers found that sporadically missing a day resulted in a tiny dip in how automatic it was the next day, but had no longer-term consequences. So, if you stumble or forget on one day, just pick it back up the next.
Sixty-six days might seem like a long time, but be reassured that it does get progressively easier with time, and you only have to maintain your motivation until the habit forms.
The magic of habits lies in their persistence even after we lose conscious motivation or interest. Of course, the reverse can happen too. Habits are great if the contextual cue of using the toilet can mindlessly lead you to the action of washing your hands, but not so great if your brain forever connects a daily happenstance with a not-so-healthful act. If you do pick up a bad habit, how can you go about breaking it? I’ll cover that next.
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- Wansink B, Sobal J. Mindless eating: the 200 daily food decisions we overlook. Environ Behav. 2007;39(1):106-123.
- Cleo G, Isenring E, Thomas R, Glasziou P. Could habits hold the key to weight loss maintenance? A narrative review. J Hum Nutr Diet. 2017;30(5):655-664.
- van't Riet J, Sijtsema SJ, Dagevos H, De Bruijn GJ. The importance of habits in eating behaviour. An overview and recommendations for future research. Appetite. 2011;57(3):585-596.
- Rothman AJ, Sheeran P, Wood W. Reflective and automatic processes in the initiation and maintenance of dietary change. Ann Behav Med. 2009;38 Suppl 1:S4-S17.
- Gardner B, Lally P, Wardle J. Making health habitual: the psychology of 'habit-formation' and general practice. Br J Gen Pract. 2012;62(605):664-666.
- Orbell S, Verplanken B. The automatic component of habit in health behavior: habit as cue-contingent automaticity. Health Psychol. 2010;29(4):374-383.
- Verplanken B, Wood W. Interventions to break and create consumer habits. J Public Policy Mark. 2006;25(1):90-103.
- Singh B, Murphy A, Maher C, Smith AE. Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants. Healthcare (Basel). 2024;12(23):2488.
- Lally P, Van Jaarsveld CHM, Potts HWW, Wardle J. How are habits formed: Modelling habit formation in the real world. Euro J Social Psych. 2010;40(6):998-1009.
Motion graphics by Avo Media
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
We may make hundreds of food decisions every day, yet the vast majority pass under our conscious radar. They happen more automatically, without conscious reflection, deliberation or even awareness. We may be able to take advantage of this mindless eating, though, by harnessing the power of habit formation.
It’s been said that “Most of the time, what we do is what we do most of the time.” Many of our eating habits are indeed just that, habitual. And the busier and more distracted we are, the more likely we are to fall back on habits. That’s what they’re there for. They’re like reflexive subroutines your body uses to free up mental resources. That can work against us, in the case of bad habits, or for us, in the case of good. Imagine if you had to add “buckle seatbelt” to your to-do list every day? If you’re in the habit of buckling up, your hand will start reaching for it without you even knowing.
Once you do something long enough, it worms its way into your brain. Your brain commits the actions to memory, and can whip them out when needed to automate away some of your cognitive workload—essentially becoming second nature. The repetition of a simple action in a consistent context leads to the action being triggered when exposed to that same situation. So, do it enough times and the contextual clue—for example, getting in a car, can automatically lead to the action, reaching for the seatbelt.
Habits are defined as “learned behavioral responses to situational cues.” So, it has two parts, the cue and the action. The cue can be any context. It can be an event or a time, a location, or even a mood, as long as it’s something frequently and consistently encountered in daily life. Do something over and over again in the same context—intentionally or unintentionally—and a habit can form.
How long does it take? You may have heard that habits take 21 days to form. That’s apparently a myth that originated from anecdotal evidence of how long it takes plastic surgery patients to psychologically adapt to their new appearance. If instead habit formation is actually put to the test, the average time for that habit to become automatic is 66 days. Study volunteers were asked to choose an eating, drinking, or activity behavior to carry out daily in the same context. Examples chosen include “eating a piece of fruit with lunch,” “drinking a bottle of water with lunch,” and “running for 15 minutes before dinner.” There was considerable variation in the time it took for these actions to become automatic, from 18 to 284 days, with an average of 66. About two months seems to be what it takes across all sorts of habits. The researchers found that sporadically missing a day resulted in a tiny dip in how automatic it was the next day, but had no longer-term consequences. So, if you stumble or forget on one day, just pick it back up the next.
Sixty-six days might seem like a long time, but be reassured that it does get progressively easier with time, and you only have to maintain your motivation until the habit forms.
The magic of habits lies in their persistence even after we lose conscious motivation or interest. Of course, the reverse can happen too. Habits are great if the contextual cue of using the toilet can mindlessly lead you to the action of washing your hands, but not so great if your brain forever connects a daily happenstance with a not-so-healthful act. If you do pick up a bad habit, how can you go about breaking it? I’ll cover that next.
Please consider volunteering to help out on the site.
- Wansink B, Sobal J. Mindless eating: the 200 daily food decisions we overlook. Environ Behav. 2007;39(1):106-123.
- Cleo G, Isenring E, Thomas R, Glasziou P. Could habits hold the key to weight loss maintenance? A narrative review. J Hum Nutr Diet. 2017;30(5):655-664.
- van't Riet J, Sijtsema SJ, Dagevos H, De Bruijn GJ. The importance of habits in eating behaviour. An overview and recommendations for future research. Appetite. 2011;57(3):585-596.
- Rothman AJ, Sheeran P, Wood W. Reflective and automatic processes in the initiation and maintenance of dietary change. Ann Behav Med. 2009;38 Suppl 1:S4-S17.
- Gardner B, Lally P, Wardle J. Making health habitual: the psychology of 'habit-formation' and general practice. Br J Gen Pract. 2012;62(605):664-666.
- Orbell S, Verplanken B. The automatic component of habit in health behavior: habit as cue-contingent automaticity. Health Psychol. 2010;29(4):374-383.
- Verplanken B, Wood W. Interventions to break and create consumer habits. J Public Policy Mark. 2006;25(1):90-103.
- Singh B, Murphy A, Maher C, Smith AE. Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants. Healthcare (Basel). 2024;12(23):2488.
- Lally P, Van Jaarsveld CHM, Potts HWW, Wardle J. How are habits formed: Modelling habit formation in the real world. Euro J Social Psych. 2010;40(6):998-1009.
Motion graphics by Avo Media
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How Long Does It Take to Form Healthy Habits?
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This is the first video in a three-part series. Stay tuned for How to Break Bad Habits and How to Form Good Habits.
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