If you’re trying to lose weight, a calorie deficit is (probably) where you need to focus. But that doesn’t mean you should diet forever! 

How long should you be in a calorie deficit? How long will it take to see results? And what are the signs you should stop dieting altogether?

I’m going to break it all down for you in this post.

There’s a big debate about how long you should be in a calorie deficit. And instead of slapping a number on it, my thought is this: You’re an individual, so why don’t we look at YOUR bio-individual response to guide us. Yea?

Here’s me in a “forever deficit” on the left thinking I just needed to eat less, move more, so I could lose weight. Once I learned the how long I should be in a calorie deficit and ate for my metabolic needs, everything changed.

Here are a few other nutrition resources you might find useful if you are looking for how to eat to lose fat and build muscle:

Counting Macros 101: A Step-By-Step Guide to Counting Macros for Fat Loss

The Best Macros for Fat Loss, Muscle Gain for Women

Counting Macros For Weight Loss? Don’t Make These Mistakes

Macro Food List For Meal Prep

How to Eat Clean for Beginners Losing Weight

What is a Calorie Deficit?

Let’s start at the beginning:

Everyone has what’s called a BMR, or basal metabolic rate. This is the number of calories your body uses each day just to keep the lights on—powering your lungs, heart, brain, etc.  No movement or digestion is factored into this equation. This number is fairly low, but of course, a majority of people aren’t just laying down all day. 

This means that all additional movement you do daily—from cleaning and walking around your house (activities like this are called non-exercise activity thermogenesis, or NEAT), to purposeful exercise like running or strength training, even digesting what you eat—will add to the number of calories you burn. 

For you to maintain your weight, the calories you consume from food—calories in—is equal to the calories you burn—calories out—each day. In a calorie deficit, you’re burning more than you’re consuming, and thus should lose weight.  

To create a calorie deficit, you have two options—consume fewer calories, or increase your energy expenditure. I recommend a combination of both! 

But not before you’ve done one VERY important, often forgotten or skipped altogether thing, which we’ll get to in a moment. 

How Long is the Typical Deficit?

If you Google this question, you’ll find lots of differing opinions. Some people will say 12 weeks is the maximum amount of time you should diet, some say 6 months, and some even say it’s OK to be in a deficit forever!

From my experience, there is no one-size-fits-all answer to this question, and it really depends on several factors, including your dieting history, how much weight you have to lose, and your individual biofeedback. 

For most clients in a deficit, I recommend somewhere between 2-5 months but very much depends on how the body responds.

We’ll get to some triggers it’s time to stop a calorie deficit below.

Why Should You Only Be In a Deficit for a Specific Period of Time? 

Such an important question!

When you eat in a deficit for an extended period of time, your metabolism will slow down. This is mostly due to metabolic adaptation. Your body is smart, it’s trying to do one thing – keep you alive. So, if your body is not getting adequate energy (eating at maintenance) on a typical basis it’s going to adapt to this new lower intake and will de-prioritize important functions so that you can survive.

Another reason your metabolism will slow down is muscle loss—when you aren’t consuming enough calories via food, your body will break down fat stores and muscle for energy. Muscle loss is actually really common in a calorie deficit.

Related: The Best Macros for Fat Loss and Muscle Gain for Women

In fact, most people who have done restrictive diets like 1200-1500 calories a day and lose weight, guess what, it’s mostly coming from muscle loss. This is not good as muscle is an organ of longevity and directly linked to serious health deterioration as we age.

Muscle tissue burns more calories than body fat, so just having more muscle on your body means you’ll burn more calories than you would otherwise. On the flip side, if you have less muscle on your body, your BMR will be inherently lower and thus it’ll be hard to maintain weight loss. 

So remember that very important thing I mentioned earlier that you need to be doing before you ever start a calorie deficit? 

It’s eating at maintenance first.

In order to preserve muscle mass—and see more weight loss down the line if that’s your goal—you need to give your body a break from dieting, either at maintenance or in a calorie surplus, to help increase your BMR and restore your metabolism.

The best way to combat this is eating the proper macro-nutrient breakdown for your body’s needs, grab this checklist to get started.

When is a Good Time to Be in a Deficit?

You’re primed for a deficit when you’re eating at maintenance calories or in a surplus and have been for at least 3-5 months. More if you have been a chronic dieter. 

In fact I’ve had clients where their body just never responded to a deficit (because of adaptation) but it responded even better when doing a reverse diet and working into maintenance.

Here’s an example:

I am a perfect example of this my body actually responds better to me being in a reverse and eating at maintenance really consistently than it does in a deficit because of my many years of chronic dating under eating.

12 Signs You Need to Stop Your Calorie Deficit 

How do you know if you’ve been in a calorie deficit for too long?

Here are some signals your body will give you. If you’re experiencing more than one of these symptoms, it’s time to look at coming out of a deficit.

1. Frequent headaches

If you aren’t consuming enough calories or nutrients for an extended period of time, it can result in an electrolyte imbalance, which can cause headaches.

2. Lethargy

Lack of energy is a direct result of not enough fuel, both quantity and quality. 

3. Chronic fatigue

If you’re feeling extremely run down for weeks on end, it may be a sign that your body needs more calories.

4. Moodiness

As your body tries to acclimate to a lack of nutrients, you may experience mood swings and irritability. 

5. Hitting a weight loss plateau

When you initially start a calorie deficit, it shocks your body and your body responds by burning fat stores in the place of calories that you are no longer consuming. But, our bodies are adaptable, and eventually, it will adjust to this new input, slowing weight loss. If you’re in a deficit and haven’t seen weight loss results in 2 weeks, it’s time to reverse.

6. Uncomfortable hunger

Moderate hunger while dieting is hard to avoid, and is to be expected. But, if you’re so hungry that it affects your day consistently, you aren’t eating enough, time to reverse.

7. Getting sick more often

This is a big one. Without proper fuel (and nutrients), your body is working in overdrive to stay afloat and function optimally. This is prime time for sickness to creep in, too. 

8. Getting injured more often

Sickness and injury tend to go hand in hand. This could look like you are more clumsy and seem to bruise easily or just trip and fall a lot, to your body literally breaking down.

9. Muscle loss

As I mentioned above, when you’re in a deficit for an extended period of time, your body will break down fat stores, and also muscle, for energy. If you’ve been noticing muscle loss, it might be time to come out of a deficit. 

10. Diminished results from the gym

If you’re not eating enough for an extended period of time, your energy levels will be chronically low. This means that you won’t be able to give it your all at the gym. And on the flip side, if you are able to muster up the energy to go, your results will most likely be a no-show—especially if you’re doing resistance training. Your body needs proper fuel to build lean muscle.

11. Trouble with sleep

You may have trouble sleeping in a deficit for a few reasons. If you go to bed hungry, it will be hard for your body to relax and rest. You may also be drinking more water, which can lead to nighttime bathroom breaks, or you may be ingesting more caffeine to deal with less food, and this can affect sleep as well. 

12. Menstrual Irregularity  

Ladies, if your period is irregular, or you’ve lost it altogether, it may be a sign that you’re not eating enough or have been in a deficit for too long. Your body requires fuel to function optimally, optimally including regular monthly cycles.

What Should I Do After a Deficit?

You might be wondering, how do I get out of a deficit and maintain results?

I recommend a reverse diet to maintain your lean gains just like this client did:

FAQs About Calorie Deficits

How do you know if you’ve been in a calorie deficit for too long? 

If you’ve been in a calorie deficit for too long, you may notice the following:

• Frequent headaches
• Lethargy
• Chronic fatigue
• Moodiness
• Weight loss plateau
• Extreme hunger 
• Getting sick more often
• Getting injured more often
• Noticing more muscle loss
• Have little energy for the gym
• Trouble with sleep
• Menstrual irregularity 

How long do I need to be in a calorie deficit to lose weight?

In a standard—and safe—deficit, you’d likely lose .5 to 1 pound per week. You, of course, can go slower than this or faster than this, the latter of which I don’t recommend. 

Keep in mind if you don’t want to lose muscle in the process, you may not lose as fast. Try counting macros to help you lose fat and build muscle.

What happens if you stay in a calorie deficit for too long?

You likely will not be able to maintain any results you saw from your deficit. As the body starts to adapt, you lose muscle mass, and you’ll see diminishing returns on your efforts. I like to think of a deficit as a “get in, get out” type of thing for best results.

How much of a calorie deficit is too much?

This depends on several factors as each person is an individual. That being said, I recommend always eating above your BMR to keep it safe. You need to be able to function at a bare minimum, but also have energy for your daily activities, and ideally regular workouts.

If you’ve had trouble seeing results in a deficit or can’t seem to maintain a deficit long enough to see results, more than likely your metabolism needs a boost. This is exactly what we help with in our nutrition coaching program Health Habit Society. If you’d like to learn more about how we can help, book a call.

Be sure to grab the macros checklist before you go to get started eating for your personal needs