Does Habit formation really take only 21 days?
- Sandhya Gokal
- Jul 2
- 9 min read
If you’re like me, and probably 99% of the world’s population…
You probably wish that when you decide to change things, they change overnight.
You finally put your foot down and decided it was time to lose weight. But the scale doesn’t go down to your ideal weight immediately. What is this craziness?
You walk into a grocery store, determined to stock up on all the vegetables you find. But for some reason, you still keep reaching for the chips in the cupboard rather than chopping up carrots and dipping them in the gourmet hummus that looked deliciously nutritious in the store. Huh?
Or maybe you screenshotted some pictures of built bods thinking, “That’s what I’m going to look like once I start on my weight training.” But the next day, your muscles still feel pretty noodle-like - maybe even more than normal depending on the intensity with which you attacked the weights.
There’s a pretty myth that says behaviour change takes 21 days. So maybe, in the above 3 scenarios, you recall this fact and decide to keep going for 21 days.
But will you see results? And more importantly, will the behaviour become a habit?
That’s what we’re gonna explore today.
How habit formation works
To understand why it takes a particular amount of time to change a habit, we first have to look at how a habit is formed.
Charles Duhigg, in his iconic book “The Power of Habit” proposes that habits form when you have a cue, an action and a reward. When this cycle is repeated enough times, a habit forms.
A smoker feels stressed. They smoke a cigarette. They are rewarded with a sense of calm.
But let’s go one level deeper.
When you first do an action, the brain forms a neural pathway for this action. Electrochemical impulses fire down neurons, which are like roads, connecting it to other neurons (roads) in order to make your body respond in a particular way. These roads are called a neural pathway.
The more you do an action, the faster these electrochemical impulses move down the neural pathway.
At first, the neural pathway is clunky. If it was a road, it would have potholes, not be paved properly, with bumps and splits in the concrete.
As you do the action more and more, the pathway becomes smoother - the road gets built up, paved and smoothed out.
Once the brain recognises that, “Hey, we’re using this pathway so much, it’s certainly an efficient one. Let’s make it even faster to do this action.” A myelin sheath forms around the neural pathway - it becomes a motorway with a tunnel where there are no traffic lights, no roundabouts and everything is done to make the pathway as smooth as possible.
And suddenly, that action is a habit. It is done without conscious thought or effort.
This is how we drive. This is how we complete our morning routine.
And without conscious effort, this is how we eat.
Where the 21 day rule came from
The 21 day rule is actually quite similar to the 10K steps goal. They both came about as a result of pop culture and reference to one specific resource, in this case the book “Psycho-Cybernetics”, written by a plastic surgeon Maxwell Maltz.
Just a quick observation. If you were going in for plastic surgery, then your expectation is that something is going to be significantly different. That’s why you’re getting surgery done! So, your expectation is already laying the foundation for the neural rewiring that is needed for a drastic behaviour change. And in this situation, it would indeed be an overnight change.
But the reality can be quite different. Most of us choose to change habits that have built up over years and years. Some of these habits are rooted in subconscious messaging that tells us a particular behaviour keeps us safe or happy.
This is particularly true when it comes to food, which is so essential for survival and has an incredible amount of variety. Food habits that form in response to a particular event in our lives can take years to overcome.
An example of this is if you are given candy when you are sad as a child, that can form a habit which follows you deep into adulthood, where you still turn to chocolate and sweets whenever sadness hits or you’ve had a particularly stressful day. And you might not even realise it.
And the secret truth is that we all expect behaviour change to happen way faster than it actually does. Our expectation does not match the reality - and this can lead to disappointment, the feelings of failure and shame.
So if not 21 days, then how long?
A 2024 study summed it up nicely - While habits can start forming within 2 months, it varies significantly across individuals. Another source states that it takes 18 to 254 days for a habit to form. James Clear, the author of “Atomic Habits”, says it takes at least 66 days for a new habit to form.
Which basically means…
It depends.
It depends on the habit that you’re trying to cultivate. Is it an extension of something you do already, like adding a 1 minute run into your daily walk? Or is it something completely new?
It depends on the obstacles you have to overcome - I mean, if you’re trying to eat more star fruit (also known as carambola, how neat!) in the dead of winter, that’s gonna be a pretty tough challenge since it mostly grows in tropical weather. So your access to star fruit is going to be limited and it’s going to be immensely frustrating to try and go to that specialty tropical fruit world during your busy week.
It depends on the complexity of the habit. Are you trying to turn your entire diet from the fast food, convenience food, frozen food type to a raw food, vegan diet with no sugar? That’s probably going to take a significantly longer time than you expect, since it involves
Rewiring a huge amount of neurons in your brain so that the new action becomes a habit
Retraining your taste buds to prefer new vastly different tasting food - something that can take up to 10 days but in this case will probably take a LOT longer.
Adjusting your purchasing habits so that you don’t automatically head to the frozen food aisle and skip the fresh food section. Did anyone else hear the Woolworths theme song in their heads just now? No? Just me then.
Re-examining your time management. Just coz it’s raw, doesn’t mean you don’t need to prep it! And food prep seems to take a long time when you’re just starting out. I know dhal takes me twice as long to make as it does my mum
And lastly, it depends on the kind of person you are. Are you a go with the flow kinda person, or do you prefer structure and routine?
Does Tracking behaviour help habit formation?
In 2009, a study looking at how habits are formed gathered 96 volunteers who recorded whether they completed a pre-chosen activity. In this study, it took participants 18-254 days to achieve a 95% success rate in their chosen activity.
In one of the best personal development programs I have ever done, Lifebook (highly recommended!) the Mastery stage involves tracking habits to get a better overall understanding of where you stand in relation to where you want your life to be.
Fitbit, Garmin and other fitness trackers automatically track your steps, and My Fitness Pal helps you track your food.
Tracking works because of one simple underlying philosophy - you are bringing conscious awareness to the activity.
“Huh? But Sandhya, just 2 sections ago you said that habits form to STOP me from having to think consciously about the action.”
Yes. But to form a habit, you first have to consciously do it. Then the brain has to recognise that it is beneficial and rewards you in some way. And THEN it optimises the pathway.
By bringing conscious awareness to the activity you want to habitulise, you are increasing the consistency of the action, thereby allowing your brain the opportunity to recognise it’s worth
And the number of consistent days is what differs based on the dependent factors we discussed above.
Why are we even talking about behaviour change?
Because it’s easier said than done.
Understanding the hows and why of behaviour change is one of the most important things you can learn if you’re on a healthy eating journey.
Human behaviour accounts for a large proportion of the risk of preventable deaths such as heart disease, diabetes and cancer.
And of those preventable conditions, food is one of the main factors that can be changed to reduce your risk of almost every preventable condition.
As well, it’s my experience that when someone understands something, they are just so much more likely to implement it.
If you know how much screens affect your concentration and memory, you’re more likely to try to give your brain a rest by not doom scrolling all day (or setting aside certain times to dedicate to doom scrolling. Also, doom scrolling is so fun to say and type - in my head there’s some ominous music playing each time I read it)
Contrary to the back of my high school jersey, Ignorance is not bliss. There is power in understanding and knowledge. And you know me, I’m all about giving you the secret powers to make healthy eating effortless.
So how can I change my behaviour TODAY?
We’ve discussed a few strategies you can try, but let’s make it even more succinct
Track your habit
This is the easiest way to start behavioural change. There are so many tools out there to help with this! From a simple excel spreadsheet to apps to the old-fashioned pen and book, you can start doing this straight away.
Then keep a record of how many times you do the action.
One advantage of this technique is that you have a way to celebrate your progress that is tangible. You can put in reward intervals as well!
For example, at 21 days of drinking an extra glass of water after a meal you get to buy that coat you've had your eye on. Or you get to go do an escape room with your buddies. Or you can schedule a massage. Part of the fun in this method is just coming up with rewards!
My advice is to choose one habit at a time. Unless you have done some serious soul-searching, changing one habit will make you the most consistent.
And consistency is the key to habit formation.
Give yourself the gift of TIME
We spent a fair bit of time talking about how long it takes to create a habit.
If you want to guarantee success, take the largest number you can find in this article and double it.
Then go about doing your action.
Spend your energy coins wisely
Each of us has a finite amount of energy coins that we can spend each day.
Once those energy coins are gone, we experience things like exhaustion, lack of motivation and couch potato syndrome (oops, this isn’t a real thing but I’m sure you’ve been there before)
If you have kids, you definitely know what I mean.
Not everyone uses all their energy coins everyday.
And we all have different amounts of energy coins.
So you need to be sure that the behaviour you’re trying to change doesn’t cause you to overextend your spending.
In simpler terms - choose the smallest variant of your action that you can manage to fit into your day consistently without burning out.
Doing a small action everyday beats doing a huge, dramatic action once. Every. Single. Time.
What’s in your future?
I have a secret fascination - daydreams. In year 12 I spent a whole heap of time studying how daydreams affect our future and the effect of visualisation on our perception of the future. One of my favourite fantasy books, Dreamer by Melaina Faranda, focuses on lucid dreaming.
Visualisation is a tool used by athletes, surgeons, students and pharmacists (at least one I know of) which makes success more likely.
You imagine a future outcome the way you want it, in as much detail as you can pack in. Make it as realistic as possible. And repeat this on a daily basis alongside doing the action.
You can try visualising 3 months into the future, 5 years, 10 years, when you’re 80, whatever works for you.
Make sure to choose a time frame that won’t overwhelm you - I have worked with clients where 12 months into the future is too overwhelming.
And choose a time that is believable to you. Another of my clients didn’t believe that she would make it to 80 years of age, so using 80 years old as a benchmark was completely useless.
So what are you going to do next? Change your behaviour and change your world? I'll see you on the other side!
If you're struggling with behaviour change, why not book a call with me? We can talk about strategies to get your health behaviours in line with what you want your future health status to be. Go on, do it!
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