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Eating Less Than 1000 Calories A Day And Not Losing Weight: Everything Explained

As most of us know, the trick to losing weight is reducing the number of calories you consume. This is known as a ‘calorie deficit’. 

If you normally consume 2,000 calories per day, reducing your calorie intake to 1,500 calories will result in a weight loss of 1 pound every week. The problem is, people sometimes try to lose weight faster by cutting too many calories and this ends up negatively affecting their weight loss journey rather than promoting it. 

In this post, we’ll look at why you’re eating less than 1,000 calories a day and still not losing weight. 

The Basics of Calorie Intake

As humans, we have a stipulated number of calories we need to consume every day for our bodies to function normally. This amount of calories is required to carry out basic survival processes such as breathing, pumping blood to all parts of the body, and creating energy. 

Most people are advised not to go below this calorie intake and if they decide to do so, they should never go below 1,200 calories.  The recommended calorie intake differs among different people based on: 

  • Age
  • Sex
  • Environmental temperature
  • Energy expenditure
  • Pregnancy
  • Hormonal status
  • Dieting behaviors (4)

For example, women between the ages of 26 and 50 years who are sedentary have a recommended calorie intake of 1,800 calories per day. 

Males between the ages of 26 and 40 years who are sedentary have a recommended daily calorie intake of 2,400 calories. For sedentary men past the age of 40 to somewhere in their late 50s, the recommended calorie intake is 2,200 calories per day. 

More active people such as athletes need to take in more calories as they have more energy needs from all the running, exercising, and everything else they do. 

From this information, you can see that consuming 1,200 calories a day is not recommended, let alone anything below that number, such as 1,000 calories. Eating less than 1,200 calories comes with some negative effects. 

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Effects of Eating Less Than 1,000 Calories in a Day

As highlighted above, it is not safe to eat less than 1,200 calories in a day. Here are the reasons why:


Eating less than 1,000 calories in a day can cause a serious case of malnutrition. When it comes to cutting calories, different people use different approaches. 

Some people cut calories from all food groups, while others choose to cut an entire food group from their meals. Both cases will likely cause malnutrition and here’s how it happens. 


Cutting calories from all food groups

When we say all food groups, we mean carbohydrates, proteins, and fats. The main problem with this approach is that you take in very few calories, which means you’re eating a very small amount of food. 

We eat food for energy, nutrients, and other benefits. Our body needs different nutrients in various amounts, which are determined by how much food we take in. 

When you eat food in small amounts, although you may be providing your body with all the various nutrients, the main problem you’ll face is that you’re not providing them in the required amounts, which can cause malnutrition (2). 

Cutting calories by cutting entire food groups

This is where you decide to eliminate entire food groups in order to achieve your goal of taking in less than 1,000 calories per day. Every food group is important to your body and if a certain food group wasn’t important, there wouldn’t be as much emphasis on eating a balanced diet as there is. 

Here are the main reasons why each food group is important:

  • Carbohydrates: These are the primary sources of energy (11). We all need energy to perform everyday tasks such as working, walking, and breathing. A lack of carbs in your diet can cause a lack of energy, irritability, dizziness, and general weakness. Carbohydrates also help improve your overall mood by helping to produce happy hormones as well as treating certain conditions such as constipation as most carbs have a high fiber count.
  • Proteins: These are mainly known for their building properties. Proteins help build muscles, bones, skin, and cartilage. They also help repair injured or worn-out muscles. Proteins also help with weight loss by building muscles. Muscles are metabolically active tissues and this means that they burn calories, even when you’re resting, which helps with weight loss.
  • Fats: These are sources of essential fatty acids that the body cannot produce on its own. They help with the absorption of important vitamins that the body needs, such as vitamin A, vitamin D, vitamin E, and Vitamin K (5).
  • Vitamin A helps with your vision. It also helps make your immune system stronger and helps with reproductive processes.
  • Vitamin D helps regulate the amount of calcium and phosphate in your body. Both of these nutrients are important when it comes to the formation of bones, teeth, and healthy muscles.
  • Vitamin E helps protect cells from being damaged by free radicals. Free radicals are compounds that are formed in our bodies when the food we eat is converted into energy.
  • Vitamin K helps with blood clotting and the formation of healthy bones.
  • Fats can absorb these vitamins as all vitamins are fat-soluble.

If you eliminate an entire food group from your diet, you risk not getting the different nutrients you would get from that food group, resulting in malnutrition. If you intend to significantly reduce your calorie intake, it would be wise to consult an expert before you start. 

Read more: Boxing Calories Burned: Lose Weight by Punching

Slowing Down of the Metabolism

Another negative effect of eating less than 1,000 calories a day is that it affects your metabolism by slowing it down. This generally happens as an adaptive mechanism by your body. It is called adaptive thermogenesis (2). 

What Is Adaptive Thermogenesis?

When you cut calories for some time, you start to lose weight. However, after some time, the body adapts to this reduced calorie intake by slowing down your metabolism.  This may result in a weight plateau where you eat less but don’t lose weight as your body adapts accordingly. This means the body has slowed its metabolism down to match the food intake. 

This normally happens when you cut your calories too much, and anything below 1,000 calories qualifies as cutting your intake too much. Although there is no definite number to indicate how much your metabolism may change, studies have shown that your metabolism can change by 100 to 500 calories in a day (2). 

It should be noted that adaptive thermogenesis is not a one-way process as the same happens when you eat too much. Your body adapts to your food intake by increasing your metabolism to match your food intake. This happens to prevent weight gain, but there is only so much adaptive thermogenesis can do. 

If you increase your food intake by 1,000 calories and at a maximum, your metabolism is only increased by 500 calories, you will still end up gaining weight.  This is why people are advised to eat what they need – not too much or too little. 

Loss of Muscle

Another negative effect of eating less than 1,000 calories is that you end up losing muscle. As demonstrated above, when you eat too little food, your body adapts by slowing down your metabolism. Loss of muscle can also reduce your metabolic rate. 

Why is that?

It is due to the fact that muscles are metabolically active tissues. This means that they burn calories even when you’re resting. Professors at the University of New Mexico found that 1 pound of muscle can burn 4.5 to 7 calories per day. Losing a pound of muscle mass will reduce your metabolism by that much (2).

When you cut your food intake to 1,000 calories per day or below, your body is forced to break down muscle so that it can provide your body with energy as your meals are not providing you with enough energy. This results in losing muscle and affects your metabolism as highlighted above. Gaining muscle while losing weight should be one of the goals people on weight loss journeys have. 


The Female Athlete Triad

This is yet another negative effect of eating less than 1,000 calories. Although it contains the word “athlete”, it does not only affect female athletes but all women. The female athlete triad consists of three parts: 

  • Negative energy balance
  • Disruption of the menstrual cycle
  • Low bone density

Let’s look at these points individually. 

  • Negative Energy Balance
    This is a situation where the energy you take in is less than the energy your body uses (2). When you eat fewer calories than your body uses, you are likely to experience a negative energy balance and this can result in a decline in your metabolism, an inability to do basic activities and work, and low concentration levels. Negative energy balance can also be caused by overworking or various eating disorders.
  • Disruption of the Menstrual Cycle
    This is another negative effect of eating too little food (2). Signs of this can involve delayed periods, missing periods while you’re not pregnant, and having your periods at irregular times. If you experience any of these symptoms, it is advisable to visit a health practitioner as they are signs that your body is not functioning as it should. Once you’ve dealt with this problem, your periods should go back to normal.
  • Loss Of Bone Density
    This comes from a prolonged period of calorie reduction and results in weak bones, increasing your chances of getting conditions such as arthritis (8).

Skin and Hair Problems

Consuming less than 1,000 calories a day can have profound effects on both your skin and hair health, which can lead to noticeable changes that may indicate underlying nutritional deficiencies.

Hair Loss Indicators

  • If you notice an increase in hair shedding in your hairbrush or shower drain, this can be a sign of insufficient calorie and nutrient intake.
  • Dry, brittle hair or lots of split ends can be another indicator of malnutrition.
  • Caloric deprivation often results in deficiencies of essential nutrients such as protein, biotin, and iron, which contribute to hair loss (2).

Skin Deterioration

  • Insufficient caloric intake adversely impacts the skin, causing thinning, wrinkling, and potential peeling or tearing.
  • Skin issues may manifest as dryness, lesions, bruising, broken blood vessels, and purpura, a severe form of bleeding under the skin.
  • A 2018 study established a connection between malnutrition and skin tears across various demographics, regardless of age or BMI (7).

Immune System Dysfunction

  • A 2016 study established the link between calorie restriction and impaired immune function, potentially causing recurrent illnesses (6).
  • Frequent sickness may signify an inadequate nutrient intake, which is crucial for maintaining a robust immune system.

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Eating Less Than 1,000 Calories a Day and Not Losing Weight

Some of the side effects of eating less than 1,000 calories in a day are the reason you’re not losing weight even though you’re eating too little. Here is why you’re not losing weight despite eating too little:

You Don’t Have Enough Energy

For sustainable weight loss, people are advised to check what they eat and to workout. Working out requires energy (11). The basic principle of working out is using calories to burn even more calories. Therefore, you first need to have enough calories. These calories come from eating food and as you’re not eating enough food, you don’t have enough calories.

This translates into not having enough energy. Having the required amount of energy translates to you being effective in the gym where you’re not too tired or too weak to carry out your gym session. Being effective at the gym helps you create a healthy calorie deficit and you will end up losing more calories than you consumed, thereby losing weight. 

You’re Not Consuming What You Need to Lose Weight

Losing weight isn’t just about cutting calories; various vitamins, minerals, and other components of food help with weight loss. When you cut calories to anything below 1,000, you’re likely to eliminate some foods from your diet that help with weight loss. 

For example, fruits and vegetables contain a high fiber content and fiber helps with weight loss. Fiber makes you feel full faster and longer, so when you eat foods with fiber, they reduce your calorie intake and promote weight loss.   

Your Body Is in Starvation Mode

Starvation is defined as consuming anything below your daily energy requirement, and 1,000 calories a day is way below the mark. When you consume so few calories, your body enters starvation mode in order to survive the low intake of food. This is more of an adaptation feature of the body where it starts to store calories to fuel your body (3). The more calories it stores, the less likely you are to lose weight, so this will hinder your weight loss journey. 

Your Metabolism Is Slowed

There are two reasons why your metabolism becomes slower when you have such a low food intake. The first is that your body is losing muscle and the second is due to adaptive thermogenesis (9). 

Your body constantly requires energy and if you don’t provide your body with enough, it is forced to break your muscle down to create it. The loss of muscle lowers your metabolism as muscles burn more calories even when at rest compared to other tissues such as fat tissues. The loss of these muscles takes away this calorie-burning feature of your body and results in a reduced metabolism. 

Adaptive thermogenesis is an adaptive feature of the body, just like starvation mode. When you cut too many calories for some time, you start to lose weight. However, after a while, the body adapts to you cutting your calories by slowing down your metabolism.  This results in a weight plateau where you’re eating less but not losing weight as your body adapts accordingly by slowing down your metabolism. 

Is a 1,000 Calorie Deficit Too Much?

People are often plagued with the question of whether 1,000 calories is enough for a day or what a 1,000-calorie-a-day diet plan looks like. Before looking at deficits, it’s important to understand that calories are not created equal, i.e. eating a 200-calorie candy bar filled with sugar is not the same as eating 200-calorie apples that are full of micronutrients and fiber (14).

A 1,000-calorie deficit may be suitable for weight loss, but its appropriateness is dependent on individual factors such as age, gender, weight, and activity level. Let’s take a look at the key factors for assessing the impact of a 1,000-calorie deficit:

  1. Individual Factors: Age, gender, and baseline caloric needs influence the suitability of a 1,000-calorie deficit. Younger, more active individuals are likely to be able to tolerate larger deficits.
  2. Nutritional Considerations: Such a substantial daily deficit can pose challenges in meeting nutritional needs, potentially resulting in deficiencies. Ensuring a balanced diet is a recommended alternative.
  3. Muscle Preservation: Extreme deficits may result in muscle loss. Combining the calorie deficit with resistance training can help preserve lean muscle mass.
  4. Metabolic Adaptation: Prolonged large deficits may lead to metabolic slowdown, making long-term weight maintenance difficult.

In conclusion, while a 1,000-calorie deficit can be effective, individualized considerations and professional guidance are essential to avoid potential drawbacks and support long-term success.

Read more: Calories Burned Water Aerobics, or Why Aquafit is Good For Weight Loss



  • Why am I not losing weight even with a calorie deficit?

Not losing weight despite a calorie deficit can be the result of various factors, such as:

  1. Metabolic Adaptation: Prolonged deficits in calorie intake may cause the metabolism to slow down, thereby hindering weight loss. You’re likely to experience a weight plateau despite consistently eating a calorie-reduced meal.
  2. Inaccurate Calorie Counting: Constantly underestimating calorie intake or overestimating expenditure can impede your progress. Using a tracker to understand how many calories you’re consuming each day will go a long way in understanding your intake better.
  3. Nutrient Imbalance: Focusing solely on calories and neglecting nutritional balance may lead to inefficiencies in the weight loss process. Therefore, it is advisable to eat a balanced diet rather than cutting out a food group or reducing nutritional intake completely.
  4. Water Retention: Temporary fluctuations due to water retention can mask actual fat loss.
  5. Medical Conditions: Underlying health issues or medications may affect weight loss.
  • Why do I gain weight when I eat less than 1,000 calories?

Gaining weight on a diet of less than 1,000 calories may be due to three reasons: 

  1. Metabolic slowdown: Severely restricting calories can prompt the body to conserve energy, thereby slowing your metabolism.
  2. Muscle loss: Loss of muscle mass, which is a consequence of extreme calorie deficits, can also impact weight.
  3. Water retention: The body may retain water in response to perceived deprivation. (10)

In order to achieve sustainable and healthy weight loss, it’s important to strike a balance between calorie reduction and nutritional adequacy, in addition to incorporating physical activity.

  • How can I speed up my fat loss?

Some of the recommended ways of speeding up fat loss include: 

  1. Eating plenty of protein: Consuming food induces the thermic effect of food (TEF), a temporary boost in metabolism that lasts a few hours due to the energy expended in digesting and processing nutrients. Protein, with a TEF of 20-30%, has the highest impact, not only enhancing metabolism but also helping maintain muscle mass, which prevents the typical drop that is associated with fat loss during dieting.
  2. Doing high-intensity workouts: The most universal method for speeding up fat loss is high-intensity workouts. Your muscle cells will burn energy while at rest, which helps burn fat and build muscle.
  3. Eating a balanced diet: Consume a well-balanced diet with nutrient-dense foods to ensure overall health and sustained energy levels.
  4. Getting adequate sleep: Prioritize quality sleep, as insufficient rest can disrupt metabolism and increase cravings. (1)
  • How can I fix my metabolism?

Some of the trusted ways of fixing metabolism rates include the following strategies: 

  1. Exercise Regularly: Include strength training to build and maintain muscle.
  2. Balanced Diet: Prioritize protein and other nutrient-dense foods.
  3. Stay Hydrated: Water supports metabolic activity and is essential for the body.
  4. Quality Sleep: Ensure sufficient and restful sleep.
  5. Stress Management: Practice relaxation techniques to mitigate the impact of stress.
  6. Consistent Nutrition: Opt for smaller, regular meals to sustain energy.
  7. Monitor Progress: Regularly assess and adjust your approach.

For a personalized approach to fixing your metabolism, you should seek the help of a healthcare professional or nutritionist. 

The Bottom Line

Although you’re advised to eat less if you want to lose weight, you should not eat below your basic energy needs. Most people think eating less will result in faster results and end up pushing it a bit too far. This is how a person can eat less than 1,000 calories a day and not lose weight. 

As we’ve mentioned, eating less than 1,000 calories a day will lead to a slowed metabolism rate, loss of muscle mass, malnutrition, and force the body to enter starvation mode. None of this is healthy. 

There are healthier approaches you can implement to lose weight. You can start by cutting 500 calories daily from your food intake. This is a healthy amount to cut and will lead to weight loss of approximately 1 pound every week. This is not only a healthy weight loss approach, it is also a sustainable one. 

Do you think you can eat less than 1,000 calories forever? While it can be done in the short term, it is not a sustainable practice. Some ways to lose weight include: 

  • Working out: If weight loss is what you want, cardio exercises are what you should go for. Exercises such as jump rope, cycling, and swimming burn a lot of calories.
  • Getting enough sleep
  • Drinking enough water
  • Reducing your alcohol intake
  • Better stress management

You can effectively lose weight by following these strategies rather than jumping onto a 1000-calorie deficit plan. 


This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. 8 Ways That May Speed Up Your Metabolism (2023, healthline.com) 
  2. 11 Signs That You’re Not Eating Enough ( 2023, healthline.com) 
  3. Association of Dietary Energy Intake With Constipation (2022, ncbi.nlm.nih.gov)
  4. Calories: Total Macronutrient Intake, Energy Expenditure, and Net Energy Stores (1989, ncbi.nlm.nih.gov) 
  5. Fat: the facts (2020, nhs.uk)
  6. Immune Dysfunction as a Cause and Consequence of Malnutrition ( 2016, ncbi.nlm.nih.gov) 
  7. Malnutrition is independently associated with skin tears (2018, ncbi.nlm.nih.gov) 
  8. Negative Side Effects of Eating Less Than 1,200 Calories a Day  (2019, livestrong.com)
  9. Not Losing Weight on a 1,200-Calorie Diet? Here Are 8 Reasons Why (2020, livestrong.com)
  10. Reducing Calorie Intake May Not Help You Lose Body Weight (2017, ncbi.nlm.nih.gov) 
  11. The Effects of Consuming Fewer Than 1000 Calories Daily (2019, livestrong.com
  12. The Effects of Nutrition on Linear Growth (2022, ncbi.nlm.nih.gov) 
  13. The truth about carbs (2020, nhs.uk)
  14. This Is The Minimum (And Maximum) Calories You Need Every Day (2023, menshealth.com) 
  15. We’ve heard that eating negative-calorie foods might be a good diet strategy. But what exactly are they? (2020, mayoclinic.org)
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