1000 Calorie Deficit For Fat Loss And Muscle Gain

In this article, I will explain everything there is to know about the 1000 calorie deficit, who is it for, and how to do it right.

So by the end, you will have a better understanding is this something that you should consider.

But first, let’s start from the beginning.

What Does a 1000 Calorie Deficit Mean?

In general, a 1000 calorie deficit means eating 1000 calories below your total daily energy expenditure (TDEE). TDEE is the number of calories the body burns, including metabolism, physical activity, and digestion. Being in 1000 calorie deficit creates a negative energy balance and drives weight loss.

In fact, a 1000 calorie deficit per day can create fantastic results.

It’s effective.

But not easy.

So it’s not for everyone.

More on that later.

What Does a 1000 Calorie Deficit Do?

As a whole, a 1000 calorie deficit triggers metabolic adaptations, where the body switches from using glucose as a source of calories to deriving fatty acids from adipose tissue. As a result, body fat is being utilized for energy, which creates weight loss.

It’s fast.

1000 calorie deficit can shave off 2 pounds per week (or more).

Which is why it’s so appealing.

And it can be done with a combination of diet and low-intensity exercise.

(If you plan to do 1000 calorie deficit together with exercise, I recommend doing resistance training and steady-state cardio to help you maintain lean muscle mass).

However, please keep in mind that with a long-term “severe” energy deficit, your body also starts to adapt.

This means there will be some metabolic changes happening that eventually slow down the weight loss.

  • Reduced energy expenditure
  • Changes in hormonal balance
  • Changes in gastrointestinal signaling
  • Lethargy
  • Stress
  • Appetite signals

Unfortunately, all those physiological changes can lead to re-gaining weight (source).

However, with the right approach, you can use that to your advantage.

Let me show you how.

But first.

Will I Lose Weight With a 1000 Calorie Deficit?

In general, you will lose weight with a 1000-calorie deficit. Bodyweight can decrease only when energy expenditure exceeds energy intake over a given period of time. Eating 1000 calories below your maintenance threshold call upon stored fat reserves to be used as energy and make up the difference.

Doesn’t matter how you cut it.

Your body needs calories for 24-hour operations.

  • Digestion
  • Cognition
  • Breathing
  • Blood flow
  • Movement

And even when you don’t eat.

The show must go on.

So energy will come from stored fat.

Is It Possible To Not Lose Weight on a Calorie Deficit?

As a general rule, it is not possible to not lose weight on a calorie deficit. The only way to not see the results while being in a calorie deficit is by inaccurate calculations of calorie needs, exceeding calorie intake, or being too early in the process to notice any visible changes.

Let’s break this down:

Inaccurate calculations

How do you know you’re in a calorie deficit?

Probably from online TDEE calculators.

But they can be inaccurate (source).

Because to establish your metabolic rate you need more than an arithmetic formula.

To know exactly how much energy your body burns in 24 hours at rest you need:

  • Controlled laboratory setting
  • Being hooked to a “metabolic cart”
  • Measure oxygen intake after a 12-hour fasting

Otherwise, you just guessing.

Exceeding calorie intake

It happens more often than not.

People don’t really know how much they eat.

Because they’re busy, stressed out, or distracted.

In fact, the USDA Center of Nutrition Policy did a fascinating study.

They’ve compared people’s perceptions versus the actual servings of foods.

The results show that people usually underestimate how much food they eat (source).

See below.

As you can see in the graph above, people overestimate how many vegetables, fruits, and meats they eat (compared to reality).

On the other hand, most people underestimate how much sweets they consume.

Being too early in the process

This one comes from our expectations.

From the logical side, we all know weight loss takes time.

But from the emotional side, we want results to happen now.

We hear that someone lost a crazy amount of weight in a short period of time.

Or we see some photoshopped before and after pictures.

Or even some unrealistic ads on the internet.

And if we don’t digest that with a big grain of salt.

It can mess up our brains.

The reality is that any weight loss process will take a lot of time (which is why people find it hard to stick to it).

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

On average, you can lose 2 – 2.5 pounds of body weight per week on a 1000-calorie deficit. Physically active people may be on the higher end of this number because the more lean body mass you have, the more calories you can burn at rest, on top of the calorie deficit.

Also, exercise suppress your appetite.

Even something as simple as walking.

Which is great.

Because on 1000 calorie deficit you can feel hungry.

So you want to use anything you can to feel less hunger.

Or increase your hunger tolerance.

On the flip side.

Sedentary people have less muscle mass.

So they burn fewer calories at rest.

To learn more about how to do calorie deficit, without feeling hungry, check out my article.

Another way to feel less hungry while dieting is to drink coffee (yes, caffeine has been shown to block adenosine receptors and can suppress appetite).

My favorite coffee (with high caffeine) is from the company Shock Coffee, available on Amazon. Details here.

(if you buy through links on this page, I may earn a small commission).

Related article: How To Stop Worrying About Calories?

How To Do a 1000 Calorie Deficit?

The easiest way to do a 1000-calorie deficit per day without counting calories is to implement intermittent fasting. There are several ways to do intermittent fasting that ranges from daily fasts (16:8, OMAD, Warrior Diet) to weekly and bi-weekly fasts (ADF, Eat Stop Eat).

I don’t say calorie counting doesn’t work.

It does.

In fact, it is one of the most time and tested methods to lose weight.

But it’s boring.

And in the long term, it creates more anxiety and stress.

Where on the flip side.

Intermittent fasting works just as well.

But you don’t have to stick to the “rules” or numbers.

You just either eat.

Or you don’t.

Check out my guide on how to do one meal a day for beginners to learn more about how you can get to a 1000-calorie deficit without worrying about calories.

Is a 1000 Calorie Deficit Safe?

In general, 1000 calorie deficit is safe. In the short term, doing a 1000 calorie deficit is achievable and can lower calorie intake which creates negative energy balance and weight loss. However, in the long-term, it can lead to metabolic adaptations and a weight loss plateau.

Here’s how it works.

The longer you stay in a large calorie deficit:

  • You have more cravings for foods you like
  • You have more stress because of those cravings

Which can end up in overeating or binge eating.

Plus, some people already have more stress in their life than others:

  • Relationship stress
  • Caregiving
  • Financial stress
  • Loneliness
  • Work stress
  • Poor social support
  • Illness
  • Injury

And if that’s the case.

Then even a small calorie deficit may be too much to handle.

That’s why some people thrive on a 1000-calorie deficit (or more).

Others panic.

Freak out.

And raid the pantry to binge.

Because they use food to reduce stress.

That’s why 1000 calorie deficit is not a good fit for everyone.

Is a 1000 Calorie Deficit Too Much?

In general, 1000 calorie deficit isn’t too much. People who have higher hunger tolerance and stress tolerance can sustain longer on the energy deficit. However, people who have lower hunger and stress thresholds should cycle high-calorie days with low-calorie days.

It all depends on who you are.

How you react to physical hunger from your gut will determine:

  • How long can you do it
  • How often can you do it

And to be clear, there is nothing wrong with admitting that 1000 calories is too much for me.

If that’s the case, then feel free to:

Cycling your days means you eat 1000 calorie deficit on 2-4 days in a week.

And the rest on days you eat as normal.

This will help you work on your hunger and stress tolerance.

To learn more on how to do intermittent fasting for 5 days a week, check out my guide.

Will I Lose Muscle On a 1000 Calorie Deficit?

In general, you can lose muscle on a 1000-calorie deficit. Muscle loss occurs when muscle protein breakdown exceeds muscle protein synthesis. This usually happens on hypocaloric diets, without adequate intake of dietary proteins.

Eating more proteins will prevent muscle loss.

Which is something that you have total control.

Because you control what you put in your shopping cart.

And to your mouth.

Can You Build Muscle In a 1000 Calorie Deficit?

As a whole, you can build muscle on a 1000-calorie deficit. However, achieving an optimal muscle protein synthesis on a 1000-calorie deficit can be unrealistic for most people. Optimal muscle protein synthesis requires regular protein intake throughout the day and progressive overload.

It can be done.

But you need to:

  • Eat high-protein meals every 3-4 hours to stimulate MPS
  • Strength training with high and medium loads (65−85% 1RM)
  • Resistance training with high volume (28−30 sets/muscle/week) 
  • Optimize your nutrition around workout time with a high-leucine and glucose

Which is hard on a calorie deficit (source).

But don’t get me wrong.

You can build muscle.

But it won’t be your optimal level.

Not Losing Weight With 1000 Calorie Deficit

If you’re on 1000 calorie deficit, and you’re not losing weight, it means you either calculate wrongly your calorie intake, you get started with your weight loss plan and you don’t see the results, or you’re having some mindless eating episodes that you don’t include in your numbers.

The easy way to fix that is using the food journal.

Not to write down calories.

But to just write down everything that you eat.

This way you increase your self-awareness.

And you’re 100% sure what went wrong.


Being in a 1000-calorie deficit is not easy. In the short term, it is a fast track to losing 2 – 2.5 pounds of body weight per week.

But in the long-term, it can create more stress and anxiety.

Which means it is not sustainable.

At least not for everyone.

Michal Sieroslawski

Michal is an exercise physiologist (MSc), nutrition coach, Ashtanga teacher, and fitness blogger. He shares his successes and failures to help busy men and women squash down 20, 50, or even 100 pounds of fat without leaving their home.

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