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A low calorie diet is not healthy

A low calorie diet is not healthy

This is why you don’t need to stress over calories to be healthy

If you’ve tried following a low calorie diet before, you may have noticed that over time you experience fatigue, disturbed sleep, poor concentration and obsessive food thoughts. You may have pushed through believing a low calorie diet was healthy, but these symptoms indicate the stress you are putting your body under. They are not a sign of health.

Here’s why you shouldn’t follow a low calorie diet and what you can do instead.

What is a low calorie diet?

A calorie is a measurement of energy provided by food. So the number of calories in a food indicates (very roughly) the amount of energy your body will receive.

In research and according to diet marketing, a low calorie diet is generally considered less than 1200 calories per day. Although, an adult body needs much more than this to be properly nourished. As everyone’s energy requirements vary, a low calorie amount can also vary from person to person and anything less than what your unique body needs can be considered low calorie.

The first study on a calorie reduced diet averaged about 1700 calories each day (quite liberal compared to a low calorie diet today). Even at this amount, the men in this study displayed extreme physical, mental, behavioural and social changes severely affecting their health and disrupting their quality of life (1).


Eating low calorie is stressful

Your body is not supposed to run off as little calories as possible. One way your body tries to help you find more food is by producing more cortisol, a stress hormone. Cortisol helps us to stay alert and ready to respond, in this case, ready to find more food. 

In a short term situation, our stress response is helpful. However, if cortisol is raised for too long, it means we are unable to relax, have poorer sleep, it can affect our digestion causing bloating and other gut discomfort and it puts us at higher risk of chronic disease such as heart disease (2).

Additionally the effort of tracking and counting calories, planning and saving calories for later in the day takes up a lot of headspace. Not only does it take focus away from other areas of life, people who are calorie counting also report feeling more stressed (2).


You will obsess over food

While your raised cortisol is keeping you alert to find food, your body will also make sure you are thinking about food all the time. Thinking about food is a natural hunger signal but if you are always hungry, you will be thinking about food in place of work tasks, social conversations and other ambitions.

Even if you are eating a lot of bulk, such as tricking your body into fullness by consuming a lot of low calorie foods, you will likely not feel satisfied. When your mind perceives a food you have eaten is low calorie, you not only feel hungrier after eating but also your body’s hunger hormone, ghrelin, remains high regardless of the actual calorie content of the food (3). The intense focus on eating low calorie foods, can make you hungrier, less satisfied and obsessing over food.


A low calorie diet will make you obsess over food


When you eat less calories, your body uses less calories

After a short “honeymoon” phase, your body will make adjustments to reduce the total calories your body uses to match the calories you take in. This is a basic survival mode called starvation syndrome to stop you wasting away.

It will stop providing calories to parts of your body that are not important for your immediate survival, to prioritise keeping you alive. For you this means you may feel more fatigued, have less motivation to be active, or have poor concentration and focus and you will stop losing (or even start gaining) weight even while eating low calorie. (4)


You risk a nutrient deficiency

To cut out calories you are going to have to cut out high calorie foods and/or eat very little quantity of food. High calorie foods often provide different nutrients to those that are in low calorie foods which can put you at risk for a deficiency. Or if your total quantity of food is low, you are also eating less nutrients, putting yourself at risk of not getting enough.

Then there’s the impact of changing whole foods to make them low calorie. Often, fat or carbohydrate is removed and this can change the way the food is absorbed and metabolised. For example, choosing a fat free yoghurt might impact absorption of some of the nutrients in the yoghurt that require fat to absorb them.


How do you know how many calories to eat

If you are counting your calories, chances are you are not getting enough. The general guidelines are lower than the average amount of calories a human body needs and many diets or “lifestyle plans” advise calorie amounts that are not enough for an adult.

As energy needs vary across people and even vary each day, there is no way we can do the complex work of our body in figuring out how many calories are optimal. This is why it is so important to start with improving your relationship with food, so you can feel when, what and how much is most supportive for your body without having to second guess or obsess over food and calories.

How to improve your relationship with food

Improving your relationship with food requires working on the same team as your body, rather than fighting against it with strict rules. You can start by noticing and honouring it’s hunger signals and getting curious about how satisfied you feel after eating. Noticing when you have strong emotions and how this changes your eating behaviours.

Before being able to build a strong connection with your body, you need to be eating enough so that your body is no longer experiencing stress. To get started, eating regularly throughout the day and including some higher and lower calorie foods at meals can help provide some structure as you learn to connect back with your body.


 To start working with your body and stop obsessing over calories, download your free e-book “5 steps to get started with intuitive eating



Author Bio:

Written by Emma Townsin, Registered Dietitian and Certified Intuitive Eating Counsellor

Emma is the founder of Food Life Freedom and the host of the Food & Life Freedom Podcast. For personalised support to stop stressing over health and heal your relationship with food and your body, learn how you can fast track your way food and life freedom.




  1. Eckert, ED et al. 2018. Minnesota starvation experiment. A 57-year follow up investigation and review of the Minnesota study on human starvation and its relevance to eating disorders.
  2. Tomiyama et at. 2010. Low calorie dieting increases cortisol
  3. Crum and Corbin. 2011. Mind over milkshakes: Mindsets, not just nutrients, determine ghrelin response.
  4. Hunger et al. 2020. An evidence based rationale for adopting weight inclusive health policy.

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