Why You Shouldn't Be Doing Extremely Low Calorie Diets

The most common approach people take while trying to lose weight is restricting the number of calories they eat. While calorie restriction can be helpful while done smartly and mindfully, an extreme restriction can actually be counterproductive. 

Not only does it negatively impact your health, but surprisingly, it can also hamper your weight loss journey. In addition to that, it can also lead to weaker bones and reduced fertility. Read on to learn why you shouldn’t be doing extremely low-calorie diets.

How Many Calories Do You Really Need? 

The amount of heat energy required to raise one gram of water temperature by 1°C (1.8°F) is defined as a calorie. However, most people commonly think of calories as the unit of measurement for the amount of energy your body gets from the foods and beverages you consume. 

Calories are required by your body to function and aid three main processes: 

1. Basal Metabolic Rate (BMR)

Your BMR refers to the number of calories required by your body to cover your essential functions, including brain, heart, lungs, nervous system, and kidneys. 

2. Physical Activity

This refers to the number of calories required by your body to carry our daily activities and fuel everyday tasks and workouts. 

3. Digestion

Just like your external activities, your internal activities are also dependent on the number of calories you consume. This means that calories assist digestion and metabolize the foods you consume. This is referred to as the thermic effect of food (TEF). 

Depending on your age, height, weight, physical activities, and other factors, you will need a certain amount of calories to maintain your weight. For instance, a 25-year old male whose height is 180 centimetres and who weighs 65 kilograms and participates in light exercise will need about 2,300 calories per day to maintain their weight. 

When you eat more calories than are required by your body, it causes you to gain weight. Similarly, eating fewer calories than needed enables you to lose weight. This is why people are recommended to restrict their calorie intake while trying to lose weight. 

In order to lose half a kg per week, the same man will need to cut down their calorie intake to about 1,775 per day. Trying to lose more than half a kg per week can be very dangerous. If you do intend to do it, it is necessary to consult doctors and fitness experts beforehand. However, it is recommended to not try to lose more than 0.9 kg weight per week unless one suffers from extreme obesity. 

A Person Holding Their Head in Pain

Why Restricting Too Many Calories Can Be Harmful for You

Some people try to restrict their calorie intake to extreme limits, going as low as 600 to 800 calories. This is almost half of an average person’s basal calorie requirement. Here are a few reasons this is a bad approach for weight loss. 

1. Nutrient Deficiencies

Vitamins, minerals, and fibre can be very invisible to the average human being. Therefore, it is also easy to overlook their importance. However, these nutrients are essential for your short and long-term wellbeing. When you restrict the numbers of calories your intake, you also restrict the number of food groups. 

It is almost impossible to consume a variety of healthy foods when you are only eating 600 calories a day. This results in your diet not providing sufficient amounts of essential nutrients such as iron, folate, calcium, zinc, and vitamin B12. 

This can cause fatigue, muscles cramps, migraines, and abnormal heart rate in the short term. Over the long term, this can lead to a weakened immune system, weakened muscles, permanent hair loss, eye damage, anaemia, and osteoporosis.

2. Low Metabolism 

As discussed before, extremely low-calorie diets can actually hamper your weight loss efforts. This happens because your metabolism plays a crucial part in how many calories you burn. When you regularly eat healthy food and participate in strength training, your metabolism functions at its optimal levels

However, if you consume meagre calories, your body goes into survival mode – causing your metabolism to slow down. Think of it this way: When you don’t get enough food, your body starts thinking that food is a luxury. Therefore, it tries to hold onto every last bit of it as long as it can because it isn’t sure when it would get more food. 

This results in your body conserving as much energy as possible, hampering your metabolism. Not only does this make losing weight even more difficult, but it can also result in gastrointestinal abnormalities, such as constipation. What’s worse is that when you go back to eating normally, you may end up gaining even more weight than before. 

3. You May Lose Your Mental Edge

Just like a car needs gasoline to run, your brain needs sufficient amounts of glucose to function. But unlike your car, your brain is running 24/7. Therefore, it needs a constant supply of glucose to keep everything running smoothly. 

However, if you don’t eat enough and are hungry most of the day, you will likely not get enough glucose for your brain to function optimally. This will prevent your brain from function properly, and you may find yourself struggling with mental tasks and not being able to work at peak capacity. 

Healthy Vegan Lunch Bowl Avacado Quinoa


If you want to lose weight in a healthy and effective manner, it is crucial to have patience. Trying to lose weight quickly will often have adverse effects. Instead, safely cut down your calories and try to fill up your plate with fibre, protein, whole grains, and healthy fat. This way, you’ll be able to lose weight and keep it off in the long run.