7 Symptoms of Not Eating Enough Calories & 4 Step Treatment Guide

7 Symptoms of Not Eating Enough Calories & 4 Step Treatment Guide

Did you know that not eating enough calories may be limiting your ability to lose weight?

Caloric restriction causes a cascade of hormone imbalances that lead to a condition known as weight loss resistance.

Contrary to conventional wisdom you must eat ENOUGH calories if you want to lose weight.

Luckily, there are several signs and symptoms to help you figure out if you are indeed eating enough calories.

Use this symptoms guide to help you determine if you should be eating more calories and what to do if you aren't:


Calorie Restriction and your Body

Is it possible that you aren't eating enough and that's why you are gaining weight?

It may sound counter-intuitive, but this is a real problem that many people suffer from.

The convention advice to eat less and exercise more has created a situation in which many people suffer from a damaged metabolism.

The act of reducing the number of calories that you consume for a sustained period of time (more than 21 consecutive days) causes a number of damaging changes to your metabolism, hormones and thyroid systems. 

The result is what most people have come to know as "starvation" mode.

And this phenomenon is well documented in the literature (1):

calorie restriction leads to a damaged metabolism study

The graph above is from the "biggest loser study" which is a study that followed the contestants of the biggest loser during their journey and 6 years afterward. 

If you subscribe to the idea that reducing your calories and exercising more will help you lose weight then this study should help shatter that belief.

This study showed that greater than 90% of the contestants of the biggest loser gained all of their weight back over time. 

But more importantly, it showed that the reason this occurred was due to persistent metabolic "adaptation".

Metabolic adaptation is a fancy word to describe a damaged metabolism.

They found that these contestants were burning on average 700 calories LESS per DAY than when they started their journey.

Let's put this into perspective:

Let's say that your body wants to burn 2,000 calories per day and this is your "norm".

You decide (against your better judgment) to reduce your calories down to 1,200 per day in hopes that you will lose weight. 

You do this for 1 month and you are able to lose maybe 5 to 10 pounds.

After that month you decide to increase your calories back up to 2,000 per day and guess what happens?

You regain all of the weight you lost over the next 1-2 months.

Not only do you gain your weight back, but you've just damaged your metabolism in the process. 

So how does this happen?

weight gain and fat mass over time with calorie restriction

To compensate for the lack of calories your body doesn't keep burning 2,000 calories per day.

Instead, it REDUCES your basal metabolic rate (2) down to the amount that you are eating - in this case, 1,200 calories per day.

The problem is that once you start eating 2,000 calories per day, your body sticks to the 1,200 calories per day and now you are in a situation where you regain all of your lost weight. 

This is just the beginning. 


Because the advice coming from Doctors, nutritionists, and personal trainers are that you just need to eat even LESS and exercise even MORE in order to lose weight.

This leads you to consume fewer calories and damage your metabolism in a vicious cycle.

The problem is that this cycle leads to characteristic symptoms that all indicate you have a condition known as metabolic adaptation syndrome, otherwise known as metabolic damage.

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7 Signs that you are NOT Eating Enough Calories

We will talk about how to deal with a damaged metabolism later, but for now, we need to focus on the signs and symptoms that indicate you are not eating enough.


Your body isn't stupid.

You can't "trick" your body into losing weight by simply reducing the number of calories that you consume.

Your body will respond by changing hormone levels in your body (3) that directly or indirectly lead to a reduction in your basal metabolic rate and energy production.

The symptoms associated with not enough calories are the direct result from these adaptations.

#1. Your weight keeps climbing even if you are undereating (Eating less than 1,200 calories per day)

This is a difficult symptom for many people to understand. 

How can you possibly gain weight if you are eating only 1,000 calories per day?

Is that even possible?

Cortisol and metabolism

It is absolutely possible and it is something that I see all the time.

The amount of calories that you burn each day is largely dependent on something known as your basal metabolic rate. 

Your "metabolism" is another name for your basal metabolic rate and this number is responsible for the majority of energy that you burn in the day.

In fact, this number represents around 70% of ALL calories that you burn each day.

Compare this to exercising which may only account for 5-20% of the calories that you burn in a day (depending on how aggressive you exercise).

Just looking at the numbers it's easy to see why your focus should be on your metabolism and NOT on how much you exercise.

Even if you were able to double the number of calories that you burn with exercise you would only be doubling a small number (a few hundred calories).

If you focus on increasing your basal metabolic rate even 10-20% you will have made a much bigger impact on your energy expenditure and thus your ability to lose weight. 

If you are gaining weight despite eating a low-calorie diet then it's VERY likely that you are suffering from metabolic damage or a damaged metabolism. 

The answer to this problem is not to continue to restrict your calories. 

Instead, you have to take a systematic approach to slowly increase your calories to improve your basal metabolic rate and reverse hormone damage that may accompany metabolic damage in your body. 

#2. You feel cold

Many people who are not eating enough calories also suffer from changes to their body temperature. 

Studies have shown that there is a correlation between the amount of heat that your body produces and the number of calories (4) that you burn in a day (your metabolism).

Your body creates heat by burning energy and that energy is released as heat. 

People that have a damaged metabolism often notice that their body temperature is lower than normal.

Instead of a body temperature around 98.6 degrees they may be 1 to 2 degrees lower than that at rest.

In addition, these patients also suffer from symptoms such as cold hands, cold feed or cold intolerance.

These people often wear socks to bed and/or they can be found in a sweater in the summer.

This reduction in body temperature is due to a combination of reasons, but certainly, a reduction in thyroid conversion is certainly to blame.

Studies have shown that caloric restriction causes a reduction in peripheral thyroid conversion (5) and an increase in an antithyroid metabolite known as reverse T3.

This increase in reverse T3 helps put on the "brakes" to your metabolism which also causes a reduction in energy production.

#3. You are constantly fatigued

If your body isn't producing enough energy (outlined above) another symptom will be the subjective sense of having low energy or being fatigued. 

The "energy" that your body produces largely occurs in the mitochondria and it is pumped out in a molecule known as ATP or adenosine triphosphate.

energy levels and mitchondrial function

It's helpful to think of your mitochondria as a machine with varying degrees of efficiency.

As you reduce the number of calories that you consume your body will send signals to your mitochondria to reduce the efficiency (6) and production of energy from the cell. 

changes in cortisol when not eating enough calories

A reduction in even 5-10% of energy production may result in severe symptoms body wide as your mitochondria slow down energy production. 

You can "rev" back up the engine by providing certain cofactors involved in mitochondrial energy production like the B vitamins. 

This may explain why people suffering from low energy tend to respond to B vitamins.

#4. Your Hair is falling out

Another indication that you are not eating enough is that your hair is changing (and not for the better). 

Hair changes may include any of the following: 

  • Overt hair loss
  • Changes to hair texture or thickness
  • Thinning hair
  • Receding hairline or male patterned baldness
  • Split ends or damaged hair shafts
stages of hair growth

Hair loss is a known side effect of rapid weight loss. 

The hair loss seen with weight loss and calorie restriction is due to a variety of factors. 


Hair loss may be exacerbated by nutritional deficiencies (7) such as zinc, iron, selenium and fatty acids from dieting itself. 


Hair loss may be caused by a reduction in peripheral thyroid hormone conversion (8) and low circulating T3 levels seen in calorie restriction. 

Hair loss is a known side effect of hypothyroidism. 


Calorie restriction is a stressful situation which causes changes to cortisol levels in the body. 

Stress and changes to cortisol levels (9) are well known to cause hair loss.

If you suffer from hair loss it's important to realize that this is NOT a normal condition or side effect. 

Hair loss can be used as a sensitive marker for hormone imbalance (thyroid dysfunction), metabolic damage and nutrient deficiencies.

If you suffer from hair loss make sure you are evaluated for all of these conditions and make sure you consider the use of highly targeted supplementation.

#5. You are irritable, depressed or otherwise not feeling like yourself

When you aren't eating enough calories you will notice slight and subtle (ok, maybe not so subtle) changes to your mood (10).

People who suffer from metabolic damage notice that they are highly irritable and often depressed. 

Studies have also linked depression to changes in appetite, cravings and food intake.

Why this occurs isn't completely understood but likely has to do with changes to neurotransmitters from the gut (serotonin), changes to hormones in the body (thyroid) and changes to blood sugar levels. 

People who suffer from this condition will notice that their mood changes rapidly once they start eating again.

If you are suffering from mood changes related to food intake then the number of calories you consume may be part of the problem. 

#6. You suffer from dizziness or lightheadedness

These symptoms are related to the autonomic nervous system.

This system is primarily mediated by a neurotransmitter known as norepinephrine (or noradrenaline).

This system is under unconscious control and is responsible for adjusting very important systems in your body such as your heart rate, metabolic rate, and control over smooth muscles. 

Calorie restriction causes problems with this system (11) which may lead to lower than normal resting heart rate even if you aren't a conditioned athlete.

It may also cause dysfunction leading to the inability of your heart to adequately respond to exercise.

This may manifest as symptoms such as dizziness, lightheadedness or the inability to tolerate exercise.

Other symptoms may include feeling dizzy upon standing.

This particular set of symptoms occurs in about 50-60% of patients consuming too little calories. 

#7. You are having trouble falling asleep or staying asleep

Lastly, you may notice that you are having issues either falling asleep or staying asleep. 

This problem is related to a combination of stress and changes to your circadian rhythm.

Your circadian rhythm is a cycle that helps to regulate processes in your body such as your sleep-wake cycle (12) as well as hormone changes throughout the day.

Humans evolved with these systems in place and even small changes to these cycles may result in big symptoms.

People who suffer from these symptoms often have a "surge" of energy at night making sleep difficult.

They also may notice changes to their heart rate such as heart palpitations that wake them up in the middle of the night or prevent them from falling asleep.

These symptoms indicate an issue with the normal regulatory circadian rhythm.

Healing your Metabolism

If you have 3 or more of the following symptoms listed above then there is a high chance that you are not consuming enough calories.

Knowing you are not eating enough calories is good to know, but it's more important to make sure that you do something about it.

Most people who are not eating enough calories do so because they notice that it is the only way to maintain their current weight.

They know that if they consume more calories they will likely gain some weight.

And, unfortunately, this may be required in order to get your metabolism back to normal.

Fortunately, this weight will eventually be lost again - but it may take some time. 

The worst thing you can do is continue to keep your calories low and cause further damage.

It's far better to regain a small amount of weight and fix the root of the problem so that you can lose weight long term later.

thyroid metabolism reset poster for side bar

#1. Eat enough calories

Part of healing your metabolism will include consuming enough calories to match your existing metabolic rate.

So how do you do this?

Assuming you don't have hormone imbalances that alter your appetite such as leptin resistance, it's actually quite easy.

When determining how many calories to consume you want to focus less on your body weight and more on your symptoms. 

By symptoms, I am referring to the combination of your energy levels and your appetite.

Your body (again, assuming you don't have issues with appetite from hormone imbalances) will naturally try to match your appetite to the number of calories that it needs.

If you suffer from metabolic damage you may find that your body only wants 1,200 calories per day and that's okay to start.

Over time you will notice that your appetite will slowly increase and this is a good thing as it indicates your metabolism is improving.

You will know if you aren't eating enough because you will have the symptoms listed above and you will also suffer from food cravings.

#2. Eat enough carbs

The next step is to make sure that you are consuming enough carbohydrates. 

People under significant stress and those with thyroid issues may need higher than normal carbohydrates for a short period of time. 

The reason is that carbohydrates (from healthy sources) help to improve cellular thyroid function and cellular cortisol function.

They also increase energy production (13) which may alleviate the symptoms of fatigue that patients who aren't eating enough calories often experience.

You need to make sure you get these carbs from healthy sources so if you decide to increase your carbs use these sources:

  • Organic fruits
  • Starches such as potatoes and sweet potatoes
  • Orange juice
  • Dates
  • Lactose from dairy if you tolerate it

These sources of carbs work best for people with low energy. The amount that you will need to consume depends on the amount of metabolic damage that you have. 

The length of treatment also depends on these same factors.

Some temporary weight gain may be seen while increasing carbs, but it will be necessary to heal your metabolism long term.

Avoid these sources of carbs:

  • Breads
  • Pastas
  • Rice
  • Flour

These carbs will result in increased insulin levels which will exacerbate cortisol levels and may cause weight gain. 

#3. Take the right supplements

You should consider the use of targeted supplements to help normalize hormonal systems in your body. 

Which supplements you use will largely depend on which problems you are suffering from.

Below I've included a list of supplements targeted to specific hormonal conditions that tend to accompany metabolic damage:

Click on the links for a more in-depth explanation. 

#4. Check your hormones

Lastly, you will want to be evaluated for co-existing hormone imbalances. 

Depending on the severity of metabolic damage that you are suffering from you may need to be aggressive in your treatment of these imbalances. 

The best way to target your treatment is to first identify the presence of these imbalances and then create a treatment plan if necessary.

If you have known metabolic damage (meaning you have damaged your metabolism from eating too few calories) then I recommend you evaluate the following serum hormone levels:

Treatment will depend on which hormone imbalances you have. 

Back to you

The bottom line?

Not eating enough calories may paradoxically contribute to weight loss resistance and make weight loss impossible long term.

This largely has to do with systems that adapt to caloric restriction long term which results in a decrease in basal metabolic rate.

To find out if you are not eating enough calories you can easily assess your symptoms clinically.

If you have 3 or more of the symptoms outlined above then it is likely you are not consuming enough calories.

Treating this problem may result in temporary weight gain, but improving your metabolism will be required for long term weight loss.

Now it's your turn:

Are you eating enough calories? Are you suffering from the symptoms listed above?

Tell your story or leave a comment below!

References (Click to Expand)

signs and symptoms you are not eating enough calories

Dr. Westin Childs

About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 45,000+ people have used them over the last 4.5 years. You can read more about my own personal health journey and why I am so passionate about what I do here.

29 thoughts on “7 Symptoms of Not Eating Enough Calories & 4 Step Treatment Guide”

  1. Hello, Dr.Childs, I’m really happy I found your blog and find it really educational. I’ve been recently diagnosed with Hypothyroidism and am on Thyroxine medication – still considering whether I need to switch to T3 including meds like advised in many of your articles (as you can imagine my doctor won’t be easily convinced). However, this article got me thinking if I am actually starving myself – I am counting strictly my calories… So my question is how do I calculate an estimated BMR so I don’t eat too little?

    • Hi K1kkz,

      As a general rule if you are going hungry each day then you are not eating enough. Testing your metabolic rate is difficult and inaccurate so unless you have an indirect calorimeter you may need to use surrogate markers such as body temperature and resting heart rate.

  2. You decide (against your better judgement) to reduce your calories down to 1,200 per day in hopes that you will gain weight.

    Did you mean lose weight in the sentence above?

    • Hi Dr. Poteet,

      Yes, it should read: “You decide (against your better judgement) to reduce your calories down to 1,200 per day in hopes that you will lose weight.”

      The typo has been fixed, thanks for bringing it to my attention.

      • Thanks…personally struggling with this….just had two parathyroid tumors removed…I insisted after watching it for a few years…now I have osteopenia…and apparently thyroid issues…I struggle to keep my weight down…exercise for 1.5 hours a day and have reduced my caloric intake too low…apparently compounding the issue….ugh so frustrated…on 5 (32.5 mg) nature throid now …hoping to increase it….so frustrated in this body of mine…you are a very dedicated Dr. Thanks for helping so many people with all you do.

      • Take a look at this sentence on your site…it sounds funny and has a typo.: Most people when they switch to armour thyroid except that their extra weight will magically start shedding off… Most people expect that when they switch to armour thyroid, that their extra weight will magically start shedding off…..something like that anyway. Hope you are doing well

  3. Thanks for the information.
    It’s not clear the right amount of calories to consume.
    I know that we are different. However, Is there a way to know how many calories to consume depending on the weight, height and age?

    Thanks a lot

    • Hi Rose,

      You can get a general idea with certain equations assuming you have no metabolic dysfunction but that isn’t helpful if you have a history of dieting or calorie restriction.

  4. dear dr. Child , i’m a 73 yrs. old woman . I have hypothyroid . my dr. refuse to check my ferritin level because my hemoglobin is ok .now I see another dr. who refuse to check my T3. i’m losing my hair , I cant sleep at night . I would like to try your vitamins but before I do I would like to know if it interacts with warfarin , I have to take it for the rest of my life because I have factor v .please help me I feel like nobody is listening to me . I take 1000 IU of vitamin D by recommendation of dr. my folic acid is low my B12 is 690 . I don’t understand why they don’t want to look any further as far as vitamin deficiency is concern I ‘am so frustrated I could scream at them when I have a visit with them . they think I should take more valium to sleep , and take more antidepressant . another words a band aid solution . I am fed up . Please can you help me . thank you .

  5. I have a damaged metabolism due to very low calorie diets and several HCG diets. Kaiser tested my metabolism rate and found that I was in the low 5% of the population and said that if I ate more than 1050 calories I would gain weight. So I’ve been trying to keep my calories at around 800 per day. I’m going to go on your 60-day metabolism Reset program, I have Hashimoto’s, and my question to you is should I start with 1200 calories a day or the 1500 calories that you suggest as a minimum??? I take synthroid but I’m trying to switch to T3 cytomel because I know my body needs it and it worked for me years ago.

    • Hi Sandi,

      In order to fix your metabolism, you will HAVE to increase your caloric consumption. The best way to do it is to stop counting the calories and match the food that you eat to your appetite. The amount of food that your body tells you to eat is the amount that you should be eating (from a calorie perspective).

  6. Wow! I am so happy that I found this. When I was 29 I started taking Adipex(1 am, 1/2 pm) and maxzide. From April to Sept I lost 30 lbs. Stopped taking it for about 4 months, ate unhealthy foods, gained about 15 lbs back, started the plan again lost it again in a matter of 3-4 months then stayed on it for maintenance for about 5 months. Ate unhealthy again for about 6 mo and Gained everything back. At 31, I tried the plan again, without the diuretic, and for 4 months, haven’t lost a lb. and was severely irritable! Doc changed the prescription to phendimetrazine, still nothing. Now after reading this, I’m worried about thyroid and hormones and don’t know how to find a Dr that will take the time to help me.

  7. Hahaha….. Can I eat so little that my body will eventually break all the laws of physics and become so efficient I don’t need any calories at all.
    If what you say is true, how do anorexics exist? Why is it so hard to get anorexics to gain weight in recovery? By what you are saying, they should be so efficient in metabolic ‘damage’ that one scoop of ice cream should fatten them back to regular weight. Lol

    • Hi Jen,

      I’m not sure I understand your question. Anorexics do experience exactly what you are saying. They gain weight very easily after eating relatively little which triggers their anorexia in a vicious cycle. And it’s certainly not hard for anorexics to gain weight in recovery, as long as they are eating. What you find is that they are hesitant to eat because they gain so much weight so easily.

      Your body has a basic set of functions required for cardiac function and brain activity for which your body will not go lower and that number is probably set around 600-1,000 calories per day (depending on the individual). So even if you are anorexic, you will never be able to get your metabolic rate down to 0 because critical functions require some amount of metabolic energy.

      If you don’t believe the information posted here then I would recommend you look further into the 18 research articles listed at the bottom of the post which highlights the physiology involved in this process. Once you read them you will probably have a much better understanding of what I am talking about here.

      • I certainly can attest to this, I have been anorexic at 19 and bulimic where I would excessively exercise and not eat. I was underweight for about a year and then tried to be “normal” due to social pressures… I gained 30% of my weight in about 4 months time. And losing that was more difficult than the first time….

  8. Hi, I’m trying to order a product online and something is going wrong. I left a message on your service could you please give me a call as soon as possible. I want to see if I can order it over the phone or if you can walk me through ordering thank you.

  9. This is the first article I found with an explanation of why my hands and feet are so cold after losing over 100 pounds taking Phentermine. I have metabolic adaptation syndrome for sure! And the worse part is that I raised my calories from 1200 to 2000-2400 a day for some time now and I am still cold. I have gained 4 pounds too! What am I to do?

  10. Sorry about using kgs, but I live in Australia.
    Big problem – I have been on diets my entire life, since I was 12. I’m 46 now & 20 years ago I lost my main weight of 35kgs, since then I’ve had 2 kids & have put 9kgs back on . I really hate feeling fat again.
    But no matter what I do, exercise allot, eat keto, eat paleo, eat less than 1200 calories a day etc. The weight simply will not move at all.
    I tried eating 2000 calories daily in healthy foods, Having my macros balanced between protein / carbs & fats but just simply couldn’t finish All the food each day & I still managed to gain 1kg in 1 week. Very frustrating.
    What can I possibly do to Kickstart my metabolism & get back into the shape I was most comfortable at? I’m 5ft 7in tall & weight 69kgs. My target weight is 60kgs. Thanks

  11. Hello, I have found this article very informative and after reviewing the symptoms this hits close to home. However, I’m still confused how to start the repair. Your advice is to listen to your body, but I’m not hungry. I’m turning 45 in a few months and currently weigh 163. That’s not ideal for a female height of 5’1″. I had thyroid cancer when I 15, fortunately, it was the least aggressive of the four and had to have my thyroid removed and radiation. With no thyroid I rely on medicine, I currently take 125mcg. Last fall my I decided to have my regular Dr. check my level with my physical (thought I would save a copay by not going to my endocrinologist). She changed my dosage down from 137mcg down to 100mcg. I put on 15 lbs within a few months and of course that was around the holidays, but that never happened in the past. When I went to my endo Dr. in Jan she started increasing my levels and plan to have more blood work done this month. Since, I’ve been working from home due to Covid19, I thought this will be a great time for me to lose weight and not be distracted by office parties and morning meetings with doughnuts and bagels. I’ve been eating very healthy and exercising (which isn’t new), but my weight stays the same. What you said about past diets is fascinating, I once did a diet where I ate very clean for a few weeks and lost 13lbs and another 7lbs in the next phase. Years later when I attempted it again – nothing happened, even though I ate the same. Same goes for Weight Watchers, worked for me once, but not anymore. What I am struggling with is how much should I be eating? If I listen to my body, some days I may not eat until 2pm and other days I feel like I want to eat all day.

  12. My wife though her intestinal were shot. Went to walk in for help. They said everything is good . To made a long story short she would not eat enough no appitte. Loss a lot of weight. Ended in hospital they had to put a feed tube in to her stomach to feed her she would not eat. She is now home with feed tube that I have to feed a liquid food four times a day. Her weight went from 105 to 74 At 1500 a day she is not gaining weight. Over 5 months no real Boul movement. I need help. What should I do she 67 years old 5 feet four.


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