Are you under-eating?

Very low in calorie diets consisting of no more than 1000-1200 calories are still used by many people who want to loose weight. In this article, we would like to tell you a bit more about calories and the amount we should consume per day. Before you decide to go on such a low in calorie diet please red this article and decide if it is really worth it.  

What is a calorie? 

Calorie is a unit used to measure the amount of energy a particular food contain. We do not only burn calories when exercising. Our body needs energy to function and this energy comes from calories. The total amount of calories which our body needs to operate all necessary functions is usually higher than the amount of calories we burn when exercising.  

Did you know that 60% of calories we burn are burned when we rest? Yes, this energy helps our internal organs to function in a normal way. The amount of energy needed for those functions is represented by Resting Metabolic Rate which can be calculated in various ways. One of the most accurate methods is to calculate the amount of metabolically active tissue in your body which can be measured through Dexa Scan. Easier and less expensive way is to use Harris-Benedict formula. You can use one of the online calculators to calculate the Resting Metabolic Rate, one of which you can find here 

So, if a person needs 1500 calories at rest, how much does an active person need? If we burn additional 300kcal a day while doing some workouts, walking or perhaps even more if we have an active job, we need to consume more calories. Eating too much results in an increase in weight as calories are deposited in fat tissue. On the other hand, not eating enough calories (when we eat less calories than we burn) leads to poor health and can be the cause of many health problems including the following: 

  • Lack of energy (you may feel very tired and have problems with concentration)
  • Vitamin deficiency (especially calcium, iron and vitamin E)
  • Hair loss
  • Hormonal Imbalance
  • Reduced fertility
  • Sleep problems

Low in calorie diet will also slow your metabolism as your body adapts to lower calories intake. Your metabolism is the energy you need for your day to day functions and also when being physically active. When you only consume 1000 calories per day - every day, your body receives a signal that it is not getting enough fuel. It then uses less energy to function. Remember that your body needs energy for your heart to beat, for your brain to function in a normal way and for all other vital operations of your internal organs. Research called "The Biggest Looser competition" shows that your body adjusts your metabolism when you start eating less calories as a result of which it might be more difficult to actually loose weight or even gain weight. Although you will loose some weight at the beginning, you may be surprised that after a few days your scale is not moving even when you consume only 1000 calories per day. This is because your body has gone into starvation mode which is also referred to as "metabolic damage" and has adjusted to the lower calorie intake.  

How to calculate the amount of calories we should consume and how much should we consume when we want to loose weight? 

You can use Total Metabolic Rate (TMR) which unlike Resting Metabolic Rate, calculates the total amount of energy you need incorporating your everyday physical activity. When you want to loose way, a good start is to reduce your TMR by 20%. Please see a formula which you can use to calculate your TMR below. You can also use one of the calculators available online.  

  1. First, you need to start with calculating your Basal Metabolic Rate (equation is different for men and women) 
  1. Then you need to multiply your BMR by your activity level.  

BMR for a man: 

BMR [kcal] = 66,47 + (13,75 x body mass in kg) + (5 x height in cm) – (6,75 x age). 

BMR for a woman 

BMR [kcal] = 665,09 + (9,56 x body mass in kg) + (1,85 x height in cm) – (4,67 x age). 

TMR = BMR x activity level 

Select your physical activity level: 

1,4 –  low activity ( little or no exercise) 

1,6 – light moderate (light exercise or sport 1-3 times per week) 

1,75 – moderately active lifestyle (about 3-5 workouts per week) 

2,0 –  a very active lifestyle ( hard exercise 6-7 times per week) 

≥ 2,2 – extremely active lifestyle 

Although, calories intake is very important to maintain a healthy lifestyle, it is similarly important to consume appropriate amounts of macronutrients: carbohydrates, fats and protein. So when we want to loose weight and we have already calculated the amount of calories intake, it is very important to know what kind of foods we need to eat- quality of our diet is crucial as some products are more nutritious than the others.  

According to the Institute of Medicine and National Academics, the correct ratio of macronutrients that we should consume is as follows: 

45–65% of their calories from carbohydrates 

20–35% of their calories from fats 

10–35% of their calories from proteins 

Carbohydrates are very important in our diet as it is a valuable energy source for our bodies. Always try to choose wholemeal products such as grains, groats, fruits and vegetables. 

Fat is no longer considered as evil! We need good fats especially to maintain our hormonal balance. The most valuable are omega 3 and 6 which should be consumed in ratio 1:4-5. Omega 6 can be found in fish, walnuts, flaxseed and linseed oil whereas omega 3 comes from vegetable oils such as sunflower oil, corn, soy, rapeseed oil. Omega 3 is also found in pumpkin and chia seeds. 

Protein is another very important element of our diet. Protein helps to build our muscles and helps to reduce feelings of hunger. Most importantly, protein is a vital component of our diet as it helps our body to build and repair our cells and tissues- it can be found in almost every part of our body even our hair and nails. We do not store protein in our bodies as fat and carbohydrates. We therefore need to remember to supply a new delivery of protein to our bodies everyday. Protein can be found in various products including eggs, almonds, oats, cheese, meat, lentils and many others.  

To summarise, although eating too little is no good for our health and does not help with weight loss in the long run, eating too much is also no good. We need to find a balance when reaching for food and to do this we need to make ourselves more aware of which ingredients are good for us and which we should try to avoid. We do not want to count the calories of everything we eat, we wouldn't feel happy when doing so...but we want to feel good in our bodies, feel revitalized and healthy and to do this we need to educate ourselves a little so that we know when reaching for food whether it is a good choice or not.  And remember to eat regular meals  (we recommend 3 main meals and 2 snacks) to provide your body with fuel it needs to perform and to make you feel good. If you don't know how to start, check our website and order one of our healthy plans. Let us show you that healthy food can be amazingly delicious! 

Fab Box is a fulfilement of our mission towards better and healthier you.  







J Mock (2019) “What is a calorie”. Available at: 

A Lewandowska (2019) Weight Loss diet. Available at: 

Ramage S, Farmer A, Eccles KA, McCargar L. Healthy strategies for successful weight loss and weight maintenance: a systematic review. Appl Physiol Nutr Metab. 2014;39(1):1-20. 

C Kresser (2019) Are you undereating. Available at: 

A Merritt (2019) BMR vs RMR. Available at: 

A Boldt (2019) The effects of consuming less than 1000 caloriesl daily. Available at: 

The Mayo Clinic Diet (n.d) What exactly is metabolism. Available at: 

A Lewandowska (2017) To loose weight you have to eat. Available at: 

K McCoy (2009)Can eating too few calories stoll your metabolism. Available at : 


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