How Long Should You Stay in a Calorie Deficit?
How long you should spend in a calorie deficit depends on how fast you can lose fat without losing muscle, and how lean you want to get.
Once you know how much fat you need to lose, and how much fat you can lose per week without losing muscle, you can easily calculate an estimate for how long your body should stay in a calorie deficit before taking a diet-break.
You’re about to start a diet…
You already know you need to eat fewer calories than you burn.
You know roughly how much protein you need to eat every day to support lean mass and your metabolism.
Maybe you even have a meal plan mapped out (and if not, we’ll have you covered there soon with our next tool coming out…)
But there’s still one question you haven’t been able to answer:
How long should you stay in a calorie deficit?
There are countless theories for the “ideal” length of time you should stay in a deficit.
Some say you should diet for no longer than 6 months.
Others say you can go as long as you want.
Some even say you shouldn't diet for more than 4-6 weeks before taking a diet break, giving your body a break before dipping back down into another dieting phase.
But the truth is like most things when it comes to your fitness…
There is no one-size-fits-all answer.
How long you should spend in a calorie deficit depends on how fast you can lose fat, without losing muscle, and how much total fat you have to lose to reach your goal from where you currently are.
Well… How fast can you lose fat without losing muscle?
That depends on:
How much protein you’re eating (if you don’t know, you can use our calculator to find out)
Whether or not and how much you’re strength training throughout the week
What the quality of your sleep is like
And how aggressive your calorie deficit is
To be safe, we don’t recommend trying to lose more than 1% of your total body weight per week.
With a moderate approach, you would aim for between .5-.75% of your total body weight per week.
And with a more aggressive approach, aiming for between .75-1% per week.
So if we know your starting point, and where your goal composition is, it’s fairly easy to calculate how long you should probably stay in a deficit.
Why is the answer a range instead of a hard cut-off?
Because even the best calculator in the world can only give you an estimate…
There are hundreds of other factors that impact how long you should stay in a deficit.
And that’s why it’s important to pay attention to something called your bio-feedback.
i.e. signals your body is sending you that don’t show up on the scale.
Examples of bio-feedback signals would be changes in your:
Hunger cues and cravings
Sleep quality & quantity
Recovery from your workouts
Fatigue and energy throughout the day
Feelings of stress and how well you’re managing stressors from your day-to-day life
The longer you are feeding your body less than it needs to sustain itself (i.e. a calorie deficit), the more it will start to signal it wants you to stop.
If you paid attention:
You would notice your sleep quality and the number of nights you have a “bad” night's sleep start to increase.
You have more intense, and more frequent periods of hunger throughout each day.
You wouldn’t be recovering as well as you normally do from your workouts.
You would have more high fatigue/low energy days' throughout the week.
Of course, all of these things are normal to a point during a dieting phase (occasional bad night’s rest, periods of hunger, etc.)
But if you track these, you’ll know when your body is reaching its breaking point.
(we provide a weekly bio-feedback check-in form you can use with yourself to know exactly when this is happening in FS Premium)
This point could be a lot sooner, or a lot later than what this calculator estimates.
If your body is responding well at the end of this time frame, you’re still losing weight, and your biofeedback isn’t out of control, then you would be more than fine to keep going.
If you’re hitting plateau after plateau, and your bio-feedback is 10x worse than when you started the deficit before the minimum length hits? Then you might want to take a diet break sooner.
The bottom line is:
How long you should spend in a calorie deficit depends on how fast you can lose fat without losing muscle, and how your body is responding to your diet and training.
