What happens when you don’t eat enough calories? 

In this article, we will answer what happens when you don’t eat enough calories, what calories are, how many calories you need, where should calories come from, how you know if you are not eating enough calories, and how to increase caloric intake. 

What happens when you don’t eat enough calories?

When you don’t eat enough calories you put your health at risk. Low-calorie diets are very common for weight loss but they are not supposed to be used in the long run because you can jeopardize your health. Some risks of not eating enough calories include:

  • Starvation Mode
  • Weight Gain
  • Nutritional deficiencies
  • Reduce fertility
  • Anemia
  • Osteoporosis
  • Loss of hair
  • Brittle nails 
  • Eating disorder

Starvation Mode

When you don’t eat enough calories your body enters into starvation mode. Starvation mode is when your body lowers its metabolism to protect itself from starvation and the main objective of this is to keep running your body with the main functions your body needs to survive. This includes breathing and circulation of the blood. 

Weight Gain

When you stay under caloric restriction for too long when you eat again, your body uses everything you are eating to replenish your body with what you need and you might start gaining weight faster than you lost it. 

Nutritional deficiencies

When you don’t eat enough calories means you are not eating enough nutrients, vitamins, or minerals. You might experience anemia, loss of muscle mass, infertility, bone mass loss, low blood sugar levels, or low high blood pressure. 

Eating disorder 

If you have been on a low caloric or restrictive diet the risk of an eating disorder increases. It would be easier to be caught with anorexia or bulimia. If you experience fear of gaining weight, extreme interest in nutritional information, excessive exercise or poor self-esteem look for medical help. 

What are calories?

Calories are defined as the unit of measurement used to count the heat your body creates from eating certain nutrients such as protein,  carbohydrates, and fats. 

According to the Journal of Nutrition, calories in humans are defined as the amount of heat needed to raise the temperature of 1 kilogram of water from 0 to 1-degree celsius. 

Calories can also be used in kilojoules, scientists more often use kilojoules. 1 kilojoule is equal to 0.000239006 of a calorie. 

How many calories do you need?

Calorie intake is based on a person’s age, sex, weight, height, and activity level so the general recommendation might be lower or higher for each person. According to the National Institutes of Health (NIH) is generally estimated calorie requirements are

GenderAgeSedentaryModerately activeActive

*Obtain from the NIH database

Where should calories come from?

Where your calories come from is very important. It is not only about calories, it is about nourishing the body with the exact amount of nutrients, vitamins, minerals, and calories the body needs. A basic guide of what food we should all eat includes

  • A variety of whole grains such as bread, cereal, pasta, and potatoes. 
  • A huge variety of vegetables especially leafy greens 
  • Fruit, all fruits should be eaten
  • Lean meat 
  • Low-fat dairy products 
  • Healthy fats such as avocado, nuts, pistachios, and almonds. 

In general, a diet for a normal healthy person should include

  • 45 to 65% of carbohydrates
  • 15 to 25% of protein
  • 20 to 35% of fat. 

How do you know if you are not eating enough calories?

When you are not eating enough for a long time your body will let you know it needs more energy to keep working. Some commons symptoms and signs that you are not eating enough include

  • Loss of energy
  • Hair loss
  • Constant hunger
  • Inability to get pregnant
  • Insomnia
  • Irritability
  • Feeling cold all the time
  • Social distancing
  • Constipation
  • Anxiety

How to increase caloric intake?

If you are low in calories the easier way to increase calories is to add more healthy fats to your diet. Some ideas include

  • Add extra olive oil to your dishes
  • Eat some nuts or almonds with your salads or as a snack
  • Eat some fruit with peanut butter
  • Add olives to your salads, pizza, or pasta
  • Add hummus or cream cheese to your vegetables or crackers 

Follow this link for more information on how to add calories to your diet. 


This article answered what happens when you don’t eat enough calories, what calories are, how many calories you need, where should calories come from, how you know if you are not eating enough calories, and how to increase caloric intake.





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