1000 Calorie Deficit: Is It Healthy & How Much Can You Lose?

A 1000-calorie deficit will help you to lose weight rather quickly, but it may not be worth it in the long run if you want to keep the weight off and be your healthiest self.

Should you do a 1000-calorie deficit? You shouldn’t do a 1000 calorie deficit unless it’s for a bodybuilding competition because one shouldn’t eat in a 1000 calorie deficit unless you need to achieve an unhealthy level of leanness for a very brief period.

Before you make a decision about whether to try a 1000-calorie deficit, it’s important to understand what it might be like, what results to expect, and if it’s really worth it.

After reading this article you’ll learn:

• What a 1000-calorie deficit is
• If a 1000-calorie deficit is healthy
• Who a 1000 calorie deficit is appropriate for
• What you could expect if you implemented a 1000-calorie deficit
• How to accomplish a 1000-calorie deficit

What Does A 1000 Calorie Deficit Mean?

A 1000 calorie deficit means that you are eating 1000 calories less than your body needs to maintain its weight every day, which would encourage weight loss.

A calorie deficit means that you’re eating less than your body needs to maintain your body weight, and in this example, you’re eating 1000 calories less than whatever your maintenance calories are.

For example, If I maintained my weight at 2400 calories then anything under 2400 calories would be a calorie deficit. But if I was implementing a specific 1000 calorie deficit, then that would mean that I should be eating 1400 calories.

• If you want to lose weight aggressively, rather than arbitrarily go into a 1000 calorie deficit, try a mini cut instead (click to read our full guide)

Is A 1000 Calorie Deficit Healthy?

A 1000-calorie deficit isn’t healthy, especially if you’re going straight from eating at maintenance to a 1000-calorie deficit without a gradual transition.

Your body always does best when it can adapt gradually to changes that are made because when you make larger adjustments it will always have an effect on your metabolism (the rate at which you burn calories).

If you were to go from eating at maintenance to a 1000-calories deficit, then your metabolism would slow down significantly to ensure that the calories you are consuming are reserved for basic bodily functions.

If your metabolism slows down, then you’re burning fewer calories and weight loss actually becomes very difficult over time.

In addition, a 1000 calories deficit would almost certainly result in a decrease in muscle mass because muscle costs your body a lot of energy.  So when energy is limited because calories are severely restricted, your body is more likely to get rid of muscle than to preserve it.

If you’re eating so little that your body decides to ditch muscle mass and preserve calories just so you can support bodily functions, then I think it’s fair to say that a 1000-calorie deficit isn’t healthy.

• Being in a caloric deficit is not enough when it comes to losing weight.  Read more in my article: Do Macros Matter For Weight Loss? 

Should You Use A 1000 Calorie Deficit? 

A 1000-calorie deficit isn’t healthy,  but that doesn’t mean that it doesn’t have its place.

A 1000-calorie deficit could be beneficial for those who are competing in a bodybuilding competition and need to be as lean as possible. To be competitive on stage at a bodybuilding show, you do have to go to extreme lengths by drastically reducing your calorie intake.

Although it’s unhealthy to do so, the decrease in calories to this extent is temporary and for a very specific purpose. Those who compete in bodybuilding are aware that being that lean isn’t healthy or sustainable long-term but it is part of the sport.

Other than bodybuilding, there is likely no other reason for someone to get to the point where they’re in a 1000-calorie deficit.

If you’re dieting just to feel better in your body, or to get “lifestyle lean” you shouldn’t get to the point where you’re in this deep of a deficit because it would take a long time to build your metabolism back up from this.

If you try a 1000-calorie deficit and aren’t able to maintain it, then you’ll actually put on weight rather than lose it in the long run, which probably isn’t your goal.

This is because when you try to diet on such low calories, your metabolism will decrease meaning that you won’t burn calories as readily, so when you aren’t able to stick to this low-calorie diet anymore and you eat more than a 1000-calorie deficit, you will gain fat more easily.

An example of this is the contestants from “The Biggest Loser” a TV show where the goal is to lose as much weight as possible in a short timeframe. The contestants lost weight rapidly by using an intense calorie deficit but ended up putting all the weight back on and more when they couldn’t adhere to it anymore.

What Can You Expect Being On A 1000 Calorie Deficit? 

When you’re in a 1000-calorie deficit you can expect to experience an array of symptoms, some positive and some negative.

In my opinion as a Nutrition Coach, the pros do not outweigh the cons, no matter how fast you want to lose weight.  

Pros

• Weight Loss. A 1000-calorie deficit will absolutely result in weight loss as long as you can adhere to it. However, many negative consequences can occur from implementing a drastic caloric deficit.  

Cons

• Low Energy. Such a large decrease in calories won’t provide your body with enough energy to put towards activities other than bodily functions. You may not have enough energy to do household chores or go for a walk.

• Decrease In Metabolism. When your intake is severely restricted your body feels the need to preserve the calories that are coming in for basic bodily functions so you will stop burning calories as readily.

• Increased Hunger Signals. Your body will likely try to encourage you to eat more food so that it can have more energy at its disposable so you may feel much hungrier than normal.

• High Risk Of Muscle Loss. When calories are severely limited, your body won’t want to waste any additional energy so it may decide that your muscle mass isn’t worth keeping and choose to use it as an energy source instead.

Related Articles:

• 200 Calorie Deficit
• 300 Calorie Deficit
• 400 Calorie Deficit

How To Achieve A 1000 Calorie Deficit 

Let’s say you’re someone who understands the adverse effects of eating a 1000-calorie deficit but decide you’d like to do it anyways.  

Below, I’ll share how to structure a 1000-calorie deficit.  But, here’s my advice before starting: 

• Know the reasons why you’re eating in 1000 calorie deficit.  As I said, there is only one valid reason to restrict your calories this much, and it’s if you’re a bodybuilder in the final stages of your competition prep.  If your goal is simply to lose weight quickly, you don’t need to suffer the consequences of being in a 1000-calorie deficit.

• Don’t eat in a 1000-calorie deficit without being guided by a nutrition coach or Registered Dietitian.  Because of the risks involved, including the potential for you to negatively impact your metabolism, you should only implement a 1000 calorie deficit when being advised and monitored by a professional.  Contact us if you need assistance.

Now that you know the ground rules, here’s how to achieve a 1000-calorie deficit.  

Step 1: Find Your Maintenance Calories

To achieve a 1000-calorie deficit you first need to know what your maintenance calories are, which you can determine by tracking your calories for a week.

By tracking your calories you can see exactly how much you’re consuming on average and how this is affecting your body weight. If after a week you see that you’re maintaining your weight, then your weekly average calories are your maintenance calories.

If you’re losing weight, then your maintenance calories are higher; if you’re gaining weight then your maintenance calories are lower. It’s important to find your maintenance before entering a deficit.

If you need a calorie tracker, I highly recommend MacroFactor.  You can check out my review of the app and why I think it’s the best on the market right now

• Related Article: Want To Lose Weight Fast? Eat These 7 Foods To Speed Up Your Metabolism

Step 2:  Start to Gradually Decrease Calories By 200-500

Once you’ve found your maintenance calories you can gradually start decreasing your calories by 200 to 500 calories at a time depending on how aggressive you want to be.

Then you should adhere to this new intake for at least a week before making another 200 to 500 calorie decrease.

My recommendation is that you decrease your calories as little as possible to see how your body responds, because if you don’t need to make an aggressive decrease to see progress then there’s no point in doing so.

Step 3: Avoid Going From Maintenance Calories To 1000 Calorie Deficit 

Under no circumstance should you go straight from maintenance calories to a 1000 calorie deficit; you should always get to a 1000 calorie deficit gradually rather than right off the bat.

The more quickly you get to a 1000-calorie deficit, the more you’ll experience the symptoms above. The more gradually you decrease your calories, the better off you’ll be.

In fact, you may find that, before getting to a 1000-calorie deficit, you’re losing weight comfortably while still feeling full and satiated after you eat.  If this is the case, you don’t need to continue dropping calories to achieve a 1000-calorie deficit.  

Step 4:  Monitor Weight Loss & Symptoms 

As you go through this gradual process of decreasing your calories, you’ll need to monitor your symptoms accordingly. 

If you start to experience extreme hunger and fatigue, you should stop dropping calories immediately, and begin a reverse diet.  

Is 1000 Calorie Deficit Too Much?

A 1000 calorie deficit is too much for most people because it’s so hard to adhere to because it’s such a low intake compared with where your body wants to maintain its weight.

With such a large deficit there is an increased risk of binge eating, which is an uncontrollable urge to eat because when you’re extremely restricted your body and mind start to crave food so intensely that it can cause you to have episodes of controlled eating.

Even if you are able to stick to a 1000-calorie deficit initially, when you can’t adhere to it any longer you can’t just go back to your previous maintenance calories without gaining a ton of weight.

This is because your metabolism will have adapted to surviving on lower calories by slowing down the rate at which you burn calories, so when you try to eat more than your 1000-calorie deficit you will gain a significant amount of weight if you don’t reverse diet.

So you see, it’s not as simple as doing a 1000-calorie deficit, and then “going back to normal” right away afterward. Partaking in such a large deficit requires lots of preparation, thought, and planning before and after your cut.

• Related Article: How To Eat 1000 Calories A Day & Feel Full

Is A 1000 Calorie Deficit Worth It? My Practical Advice

I don’t believe that a 1000-calorie deficit is worth it for anyone but competitive bodybuilders because you can achieve better weight loss results that you can actually maintain with a much smaller deficit.

A 200 to 500 calorie deficit is probably much better for you in the long run because it won’t slow down your metabolism as much, you won’t be as hungry, and you’ll probably be able to adhere to it for longer periods which will produce better results.

The negative side effects of a 1000-calorie deficit aren’t worth it if it means sacrificing your health and reducing your quality of life.

Those who compete in bodybuilding should know what they’re doing, know the time frame that they have to spend in this deep of a deficit, and have a detailed plan on how to reverse diet back out of this deficit to speed their metabolism back up after the fact.

Frequently Asked Questions

How Much Weight Can You Lose With A 1000 Calorie Deficit?

The amount of weight that you can lose on a 1000-calorie deficit will depend on how long you can adhere to it, which may not be very long. I would expect someone to lose more than 2% of their body weight per week with a 1000-calorie deficit.

Is 1000 Calorie Deficit Safe?

A 1000-calorie deficit probably isn’t life-threatening; however, it certainly isn’t healthy because it could encourage binge eating, low energy, hormonal dysfunction, and loss of muscle mass.

Will You Lose Muscle On A 1000 Calorie Deficit?

The chances of you losing muscle on a 1000-calorie deficit are quite high because this deficit is so aggressive that your body will likely start preserving energy for basic functions and muscle costs your body a lot of energy, so it’s easier for your body to ditch it.

Can You Stick To A 1000 Calorie Deficit Long Term?

A 1000-calorie deficit is not sustainable long-term because you will have no energy, you will be very hungry, and you will gain weight very easily eating very few calories because your metabolism will be so slow.

References

Howell, S., & Kones, R. (2017). “Calories in, calories out” and macronutrient intake: the hope, hype, and science of calories. American Journal of Physiology-Endocrinology and Metabolism, 313(5), E608-E612. doi:10.1152/ajpendo.00156.2017.

Eric T Trexler, Abbie E Smith-Ryan & Layne E Norton (2014) Metabolic adaptation to weight loss: implications for the athlete, Journal of the International Society of Sports Nutrition, 11:1, DOI: 10.1186/1550-2783-11-7

Fothergill, E., Guo, J., Howard, L., Kerns, J.C., Knuth, N.D., Brychta, R., Chen, K.Y., Skarulis, M.C., Walter, M., Walter, P.J. and Hall, K.D. (2016), Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity, 24: 1612-1619. https://doi.org/10.1002/oby.21538

Dingemans, A., Bruna, M. & van Furth, E. Binge eating disorder: a review. Int J Obes 26, 299–307 (2002). https://doi.org/10.1038/sj.ijo.0801949

MacLean, P. S., Bergouignan, A., Cornier, M. A., & Jackman, M. R. (2011). Biology’s response to dieting: the impetus for weight regain. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 301(3), R581-R600. doi:10.1152/ajpregu.00755.2010.