Should You Be in a Calorie Deficit for Life?

Eating in a calorie deficit is necessary for weight loss. That much is clear. But just how long, exactly, should you do it for? Find out here.

 Fitness female doing skipping workout outdoors on a sunny day. Horizontal shot

Eating in a calorie deficit is necessary for weight loss ?️

We've made that exceedingly clear in past articles (and you're probably already aware of the fact yourself, anyway!) Although … there is something super important we failed to cover on the topic.

Because at this point, you know:

The only thing missing? It’s how long, exactly, you should be in a calorie deficit. One month? 3 months? A year – or indefinitely? Let’s find out.

Only be in a calorie deficit for as long as you need for weight loss

The simple answer to your question is: only stay in a calorie deficit for as long as you need for weight loss.

Going beyond the necessary time frame can bring about some nasty side effects (which we’ll cover in more detail in just a bit).

In the meantime, though, you must be wondering … “How would I ever know the necessary time frame?”

Don't worry. I was just about to dive into a step-by-step explanation of how you could determine that.

Just note that there'll be some element of mathematics to it – so stay patient!

Calculating how long you should be in a calorie deficit for

First, know this: experts have determined that a safe rate of weight loss is anywhere between 0.5 to 1 kg per week. Keep this in mind as we work through the following example. Now, let’s assume that you have the following stats:

  • Current bodyweight: 70 kg
  • Current body fat percentage: 30%
  • Goal body fat percentage: 20%

That would mean that you'd essentially need to drop roughly 10% of your body weight (which translates to about 21 kg) – but in fat mass. Doing more math, that'll also mean:

  • Fastest-possible scenario (1 kg weekly): 21 weeks of eating in a calorie deficit to lose weight
  • Slowest-possible scenario (0.5 kg weekly): 42 weeks of eating in a calorie deficit for desired weight loss

There you have it. That's a general guideline for how long you should be in a calorie deficit to lose weight.

In other words: you need to have a very clear goal in mind even before you get to losing weight. You can’t approach it with a mindset of “Alright, let’s just eat fewer calories – and see where that takes me.”

At best, it’ll prove to be an unsustainable approach. And you’ll fall right off the bandwagon (yes, that’s the best-case scenario!)

But at worst? You could run into the possibility of eating in a calorie deficit for an indefinite amount of time! A dangerous situation.

It can be dangerous to stay in a calorie deficit for the long-term

But wait. Why is staying in a calorie deficit for the long-term dangerous?

Well, there are 2 primary reasons.

Physical health

Research finds that the longer you stay in a calorie deficit, the higher your risk of losing precious muscle mass. Meaning?

You could, ultimately, be losing weight – but end up with a ‘skinny-fat’ physique. Which isn’t ideal.

Despite landing squarely in the supposedly healthy BMI category, a person with a skinny-fat physique still stands a greater risk of suffering from chronic diseases thanks to their higher percentage of fat mass relative to muscle mass.

Thus, highlighting the importance of avoiding being in a long-term calorie deficit.

Mental health

Let’s be honest. A person on a diet isn’t the most fun individual to hang around.

You always must be mindful of what you put in your mouth, plan your schedule according to your calorie budget, and (maybe) even straight-out refuse food from your loved ones.

Doing all these daily can put a damper on your mood.

Plus, there's also the consideration that eating in a calorie deficit can start to mess with your head. There's a real possibility that you could begin to struggle with your relationship with food – or worse, your body image – as you try to achieve your weight loss goal.

What if the necessary calorie deficit for weight loss is too long?

Circling back to our previous example … you would have noticed that, in the longest-possible scenario, you’d have to diet for 42 weeks.

That’s 10 months and 2 weeks.

For most, that'll sound like an impossibly long period to be mindful about your calorie intake – and being careful about managing your calorie intake.

What should you do in cases like this? Well, you could always opt for something called a diet break.

This is where you intentionally eat in calorie maintenance for a period to regain your sanity and feel normal again – before heading right back into a calorie deficit for whatever period’s needed.

Wondering what that looks like?

Here’s an example. You could alternate between 1) 12 weeks of eating in a calorie deficit and 2) 2 weeks of eating in calorie maintenance until you've reached your weight loss goal.

I'll be honest. This will lengthen your overall dieting time for sure. You'll spend more than 42 weeks losing weight, but for all the well-being benefits it could bring about, it's more than worth it.

Here's something you should stick to life for

Bottom line? The only thing you should stick to life for when it comes to losing weight – and, subsequently, keeping it off? It’ll be staying physically active (i.e. NEAT, all forms of cardio, and strength training).

Oh, and if you need help with strength training: you know where to get it.

GymStreak's an AI-powered smart personal trainer app that not only programs but also guides you through every step of your workout routine, no matter your fitness goals.


Finkler, E., Heymsfield, S. B., & St-Onge, M.-P. (2012). Rate of weight loss can be predicted by patient characteristics and intervention strategies. Journal of the Academy of Nutrition and Dietetics, 112(1), 75–80.

Romero-Corral, A., Somers, V. K., Sierra-Johnson, J., Korenfeld, Y., Boarin, S., Korinek, J., Jensen, M. D., Parati, G., & Lopez-Jimenez, F. (2010). Normal weight obesity: A risk factor for cardiometabolic dysregulation and cardiovascular mortality. European Heart Journal, 31(6), 737–746.

Trexler, E. T., Smith-Ryan, A. E., & Norton, L. E. (2014). Metabolic adaptation to weight loss: Implications for the athlete. Journal of the International Society of Sports Nutrition, 11, 7.