Why You’re Not Losing Weight on Less Than 1,000 Calories A Day

Weight Loss Coach and Owner at 9 To 5 Nutrition
Joe is an online weight loss coach, certified nutritionist and qualified personal trainer who helps busy, lawyers, marketers and accountants lose weight and keep it off forever.

He specialises in working with people that have busy lives and don't necessarily have time to exercise and cook complex nutritious meals. Having had a 9-5 desk-job, Joe understands the struggles of juggling a hectic life with trying to maintain a good physique.

Joe has helped over 100 professionals lose weight and feel better about themselves using simple, repeatable daily habits and an easy-to-use spreadsheet to track everything.

Joe has also been quoted on several respected sites including Nike, Live Science and Health.com.

While Joe mainly works online these days, he also offers 1-2-1 personal training sessions across Sussex and Surrey.

If you want to know more, check out the about page, or get in touch

Quick Answer

Unless you’re already very light (110lbs/50kg) then you WILL lose weight on under 1,000 calories a day, as long as you’re tracking calories accurately, and eating under 1,000 calories for a long period of time

Let’s get this straight, eating less than 1,000 calories a day is considered a very low-calorie diet and will be enough for almost anyone to lose weight

Yes, there are of course very rare exceptions to this rule, but for 99% of you reading this, 999 calories a day or less absolutely WILL produce weight loss, no question.

That’s on the condition that you are eating less than 1,000 calories a day, consistently, i.e. day after day, week after week.

In order to lose weight, you need to create a calorie deficit, i.e. you need to use more calories than you eat each day, for a long period of time.

Almost everyone will use more than 1,000 calories a day (whether that’s just your body using calories to stay alive or to fuel movement or exercise), so eating less than that. Will produce weight loss.

Is it the best way to lose weight?

Absolutely not, in my opinion, it’s far too extreme and difficult to stick for most normal people, but it will theoretically work.

So, if you think you’re eating less than 1,000 calories a day, but the weight isn’t budging, what’s going on?

1. You Haven’t Been Dieting Long Enough

Most people come to me telling me they’ve started a new diet, and complain that it’s not working.

I ask them how long they’ve been dieting.

They tell me “one week”.

The fact is, one week simply isn’t long enough to see the significant weight loss or to even to gauge if the calorie amount you’re eating is enough to produce weight loss.

When you start a new diet, change ONE variable. For example, reduce the number of calories you’re eating and keep everything else the same 

Do this for 3 weeks.

3 weeks is a long enough time period for you to be able to see how these new variables actually affect your weight the way you want.

The chances are, if you are genuinely eating less than 1,000 calories a day, you’ll see significant weight loss in that period of time, most likely between 3-5lbs

2. You’re Not Weighing Every Day

This is another data-tracking-related issue.

You NEED to be tracking your weight every day, if you don’t you’ll get demotivated and quit.

How so?

Well, it’s perfectly possible to weigh yourself on a Monday, wait 7 days until the following Monday to weigh yourself again and be the same weight.

Weighing yourself daily

Does that mean you haven’t lost any fat?


It could mean that you had a big meal last night and there’s still some food in your gut.

Or you could be suffering from some water retention for various different reasons.

Or maybe you just forgot to take your PJs off.

All these things can mask fat loss – but unless you’re weighing daily, you won’t know that. You’ll get annoyed, assume what you’re doing isn’t working, and quit.

Whether you’re trying to lose, gain or maintain your weight, weigh yourself DAILY.

Trust me, it’ll keep you sane.

3. You Can’t Stick To It For Long Enough

If you say you’re eating less than 1,000 calories a day, how long is that actually for?

A  couple of days?

A week?

2 weeks?

Well unfortunately that’s just not long enough to see any meaningful results, unless you’re just looking to lose 1-2lbs

In order to lose a significant amount of weight, you need to be able to stick to your calorie target long-term.

That means months.

Can you REALLY eat LESS than 1,000 calories every day for months?

I doubt it.

At some point during that period of time, they’ll be a birthday, a work night out, a wedding, a holiday, a vacation or some other random event where you’re confronted with the prospect of delicious food and drinks.

Very few people can avoid these types of things.

It’s far better to be honest with yourself, accept that you won’t be able to skip/avoid social events (or practice restraint if you do go), and just have a higher calorie target. Yes, weight loss will take longer but it’ll be enjoyable, more sustainable and you’re much more likely to stick to the calorie deficit.

4. You’re Not Actually Eating 1,000 Calories a Day

If you’re eating less than 1,000 calories a day long term, great, you’ll almost definitely lose weight.

But if you think you’re eating less than 1,000 calories a day and you’re eating a lot more, then this could be the reason why you’re not losing weight.

It could be that you’re not tracking your calories accurately, e.g. you may not be weighing meat accurately, and you might think that you’re eating 100g of chicken when you’re actually eating 175g 


It could be that you track your meals accurately but you don’t track your snacks and bites.

It’s SO easy to eat hundreds of extra calories that you may not even acknowledge, which means it’s vital to track everything you eat, no matter how insignificant you think it is.


It could be that you’re just not tracking your calories at all, in which case you’ll have no idea whether you’re eating 1,000, 2,000 or 5,000 calories a day.

  1. You’re Not Eating Less Than 1,000 Calories a Day On Average

It might be that you’re eating less than 1,000 calories on some days, but unless you’re eating under 1,000 calories every day, you’re averaging under 1,000 every day.

Allow me to explain.

This is what your daily calorie intake would need to look like if you were genuinely eating less than 1,000 calories a day.


The average intake across the entire week is 966 calories. Fine.

But what most people mean when they say they’re eating under 1,000 calories a day is that they eat under 1,000 calories some days, but on others, they eat way more.

Because in their minds;

  • Weekend calories don’t count
  • They deserve a take away or a few drinks mid-week
  • They deserve a treat for sticking to their diet
  • A few extra calories here and there won’t matter

So, their weekly calorie intake ends up looking this;


And that is NOT ‘under 1,000 calories a day’, that’s 1,685 calories a day on average


What Isn’t The Problem?

You’ll probably hear some people claiming that ‘you can’t lose weight on less than 1,000 calories a day because your body will go into ‘starvation mode’.

Starvation mode is a myth.

Your body won’t suddenly stop burning calories if it’s not getting enough.

Think about it – if that actually happened, starvation wouldn’t be a problem, you’d have people in famine-ridden countries gaining weight uncontrollably.

Your body can’t store fat if it doesn’t have enough energy coming in, so if you’re not losing weight and you’re eating less than 1,000 calories a day, you’re either;

Is 1,000 Calories A Day Enough For Weight Loss?

Yes, for almost anyone, 1,000 calories a day will be more than sufficient for weight loss.

Exactly how much weight you’d lose by eating 1,000 calories a day (and how quickly you’d lose it) will depend on the number of calories you need to eat to maintain your weight.

Let’s say for example that you managed your weight by eating 2,000 calories per day. If you ate 1,000 calories a day, you’d lose 2lbs (1kg) per week or 8lbs (3.6kg) per month 

Below, I’ve created a handy table so you can see roughly how much weight you’d lose eating 1,000 calories a day (obviously, if you ate less, you’d lose more).


But 1,000 calories will likely mean that the calorie deficit is simply too much for most people to maintain long term.

So, while the numbers above may look exciting, they will be hard to attain for most people.

You’re far better off eating more calories and losing weight more slowly.

Yes, it’s slower and more boring but the weight loss will be sustainable.

Who Might Not Lose Weight on Less Than 1,000 Calories a Day?

As I said above, almost everyone would lose weight on 1,000 calories a day, but there are a few exceptions.

Generally, the people that might NOT lose weight eating 1,000 calories a day are;

  • Female
  • Older age range
  • Already very light (possibly sub 50kg or 110lbs)
  • Very inactive
  • Very low NEAT/general daily movement
  • Low muscle mass

So, using this TDEE calculator, we can get an idea of someone who might need to eat less than 1,000 calories a day to drop weight.

So, you can see above that a 50-year-old 5ft 4 female weighing in at 110lbs (50kg) would maintain their weight on 1,325 calories.

So, In order to lose roughly 1lb (0.5kg per week), this person would need to be eating around 800 calories a day.

You can probably appreciate however that there aren’t many people around that weigh 50kg, and even fewer that weigh 50kg and want to lose more weight, which is why the requirement to eat under 1,000 calories a day is so rare.

How Do You Eat Less Than 1,000 Calories a Day?

Eating under 1,000 calories a day certainly isn’t easy, but it is possible IF you ensure you’re sticking low-calorie-dense (or zero-calorie!) foods.

That means foods that are;

  • High in protein
  • High in fibre
  • Low in fat
  • Low-calorie density (i.e. a lot of volume for few calories)

This means eating mainly vegetables, fruits, very lean protein (white fish, chicken breast, turkey breast), low-calorie carbs like beans, pulses and potatoes, as well as low-fat dairies such as 0% fat yoghurt and milk.

Below is a list of some of the lowest calorie density foods you can eat (N.B. this is not an exhaustive list, just some examples)

2% Fat Milk0.5
Boiled Potato0.87
Chicken Breast (No Skin)1.1
Brown Rice1.1
White Fish (Tilapia)1.13
White Rice1.3
Pasta (Spaghetti)1.31
Pork Loin1.36
Whole Wheat Bread2.48

Be mindful that, if you are trying to eat under 1,000 calories a day, you’ll probably need to avoid even moderate calories density foods.

This means not eating foods that are generally considered ‘healthy’. But still pack a significant amount of calories.

Such foods include;

  • Fatty fish (Salmon, Trout)
  • Fatty Polury (Chicken Thigh, Duck)
  • Fatty red meat (Sirloin steak, Pork Belly)
  • Avocados
  • Egg Yolks
  • Fat-containing dairy (high-fat milk or yoghurt)
  • Whey protein

It also means almost totally avoiding calorie-dense foods.

These are foods that contain a lot of calories, but relatively little ‘weight’. These foods are generally high in fat and include things like;

  • Oil
  • Butter/cream/oil-based condiments
  • Cheese
  • Nut butter
  • Chocolate

Below is a more detailed list of some of the more calorie-dense foods

White Bread2.64
Burger Patty2.82
Black Beans3.41
Olive Oil8.85

Below is a sample 1,000 calorie meal plan

1000 calorie a day meal plan

Is Under 1,000 Calories a Day Safe?

Well, this really depends on your lifestyle.

If you are physically inactive, and don’t have a physically demanding job or do any active hobbies (gym, swimming, sports) then eating a very low-calorie diet shouldn’t carry any health risks.

However, if you are eating less than 1,000 calories a day AND expending a lot of energy too, then this amount of food likely won’t be enough to fuel you sufficiently

You could suffer from;

  • Dizziness
  • Lack of concentration
  • Headaches
  • Overwhelming hunger
  • The shakes
  • Feeling overly cold
  • Poor mood

Now, you might be able to cope with some or all of these symptoms if you’re sitting around at home all day doing nothing.

If you have a physical job, however, these symptoms could seriously affect your ability to do your job, or even your safety.

Even if you’re a knowledge worker, you may not be able to think logically, solve problems or be creative, so productivity could be impacted.

How Do You Know If Your Calorie Deficit is Too Much?

If you are suffering with any of the symptoms above, then you can be pretty sure you’re in too much of a calorie deficit.

Realistically, if this is the case you won’t be able to maintain this kind of calorie deficit to see significant weight loss anyway, so you’re far better off having a more manageable, moderate deficit and losing weight more slowly.

This 2021 meta analysis states that “deficits of 500–750 calories per day have been used for weight loss and are recommended by many obesity societies and guidelines”

A 500 calorie deficit generally works well for most people, that means if your maintenance calories are 2,000 per day, then you should eat 1,500 calories a day.

This is a much more realistic and achievable amount than eating less than 1,000 per day

What If You’re Gaining Weight on Less Than 1,000 Calories per Day?!

It is VERY unlikely that anyone would actually gain weight if they were eating 1,000 calories a day or less. Technically it is possible but you’d need to be very small, very light and very inactive for that to happen. Here are a few things that could be going on if you think you fall into this category;

1. You Simply Need to Eat Even Less

As mentioned if you are already small, very light and barely, there is a chance you could burn less than 1,000 calories a day, but this is a very rare and unlikely scenario. In fact if you do fit this description then gaining weight would probably much more beneficial for your health than losing more

2. You’re Not Eating 1,000 Calories Everyday

Eating 1,000 calories a day means eating 1,000 calories a day every day. Not just now and again, and not just on weekdays. Every day. If you ate 1,000 calories on weekdays then 3,000 on Saturday and Sunday then your average daily intake over a week would actually be 1,571 calories (which obviously isn’t 1,000)/

3. You’re Not Tracking Calories Accurately

You might think you’re eating 1,000 calories, but if you’re forgetting to track small bites, nibbles, oil for cooking and stuff like sauces then you may be eating a LOT more than you think. Tighten up your tracking and make sure everything that passes your lips (no) is being tracked. That means;

  • Cups of tea
  • Ketchup
  • Mayo
  • Butter on bread
  • Salad dressing
  • Oil used for frying
  • Handfuls of crisps or chips

Basically, EVERYTHING.


If you’re not losing weight by eating less than 1,000 calories a day, then you’re either an already very light person that doesn’t need to lose any more weight OR you think you’re eating less than 1,000 calories a day when you’re actually eating more.

Remember, under 1,000 calories a day means under 1,000 EVER YDAY for a significant period of time (Weeks and months, not days).

The likelihood is you’re just not tracking your calories properly.

Even so, going that low simply isn’t necessary, and is probably counter-productive for most people.

The vats majority of people will be able to lose weight by eating a lot more calories than that, and in doing so they’ll find weight loss easier, more enjoyable and more sustainable.

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