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Why skipping meals and starving do not lead to weight loss?

Why eating less and starving yourself is more likely to make you gain weight than lose it?

Weight loss is associated with improvements in both physical and mental health.

However, the main task of our brain is to ensure that our body functions properly. In other words, we should not starve ourselves (we should get everything our body needs).


When you starve yourself and lose a lot of weight, your body starts to save energy.


Your metabolism slows down, or in other words, your body reduces the amount of calories you burn.

You become more hungry, lazy, tired, grumpy…


When you are starving (your body gets significantly less energy and nutrients than before), your body starts to adapt (reduce spending and start storing reserves), and an increasing amount of calories from even the small amount you eat are converted into fat.

During any such period of fasting (read: crash dieting), weight is temporarily reduced (mainly by reducing the weight of water, muscle and gut content), and it looks like the diet is “working”.


The fat hasn’t gone anywhere, and the weight eventually comes back.

And with each next weight loss diet, the weight becomes more and more difficult to lose (the Yo-Yo effect. Read more about it HERE).


The statement that eating less means we take in fewer calories and thus can lose weight (fat) is only true when we eat a balanced diet and as much or a little less than our body needs.


If our menu is full of ultra-processed foods – starting with sweetened drinks, packet juices, crisps, crackers… to various meat products, processed desserts and so on – we can easily take in a lot more calories than we think, and our body stores them as fat.


If we take in too few calories, the body feels stress (due to lack of calories or nutrients or both) and goes into “starvation mode”, and as a result:

  1. Your metabolism becomes slower.
  2. Your fat stores increase even more.

As a result, eating less or starving yourself regularly can make you even more obese.

Low-calorie diets are not and cannot be sustainable because they cannot be followed over a long period of time without harming health.

In other words, weight loss is much more complex than simply “eating less and moving more”, as most slimming people think.


A real-life example

A young student who exercises regularly and has an excellent basal metabolic rate (2020 Kcal per day) stopped exercising to better prepare for exams.

During this time, he also started a strict weight loss diet (due to weight gain caused by low physical activity) and drastically reduced his calorie intake (the diet consisted mainly of soups, salads, coconut water and the like).

Within eight weeks, he reduced his weight to within a healthy range.


When he resumed regular training, his fitness was significantly lower, his muscle mass had decreased, but the fat mass had increased, and his energy consumption had dropped to 1850 Kcal per day.


Our bodies can adapt

Let’s take a car as an example, which can be compared to the human body in many respects.

To remain functional for a long time, both the car and the body need regular use (active lifestyle), correct fuel and maintenance of oil levels (diet and water) and timely maintenance (regular and deep sleep).


There is also one very significant difference – our body can adapt to the conditions and determine how fast or slow it should work depending on the “frequency of use”, “fuel”, and “quality of maintenance”.

Our brain is the one that determines how much energy goes into bodily functions such as breathing, digestion, maintaining circulation and blood pressure, heart rate, etc.

The body gets energy from the oxygen we breathe, the carbohydrates, proteins and fats we eat and the water we drink. All of this is converted into energy (adenosine triphosphate (ATP), which our body uses for energy production and storage at the cellular level) to ensure the survival of our entire body – about 2.8 to 3.6 trillion cells.


The hypothalamus region at the base of the brain senses the amount of nutrients stored and circulating in the body through chemical messengers – hormones – and performs two actions:

  1. Controls our food-seeking behaviour.
  2. Regulates energy expenditure (metabolism).

In other words, if we take in less energy than our body needs, it will adapt by slowing down our metabolism.


Catabolism and anabolism

These two processes are constantly at work in our bodies to sustain life:

  1. Catabolism, in which complex molecules are broken down into simpler ones, usually with the release of energy. During catabolism, large molecules such as carbohydrates, fats and proteins are broken down into smaller molecules such as glucose, fatty acids and amino acids. The energy released during catabolic reactions is often used in cellular processes or stored for later use.
  1. Anabolism is the opposite of catabolism – the process of synthesising complex molecules from simpler molecules, and it requires extra energy. For example, the synthesis of proteins from amino acids. Anabolism is necessary for the growth, repair and maintenance of cells and tissues (muscles, organs, hormones…).

Both catabolic and anabolic processes are continuous and controlled by the hypothalamus. It “switches” these processes on or off based on the amount of energy available in the body and according to its needs.

In other words, our bodies continue to burn calories even if we do nothing, even when we sleep (about 60-75% of calories we burn daily do not relate to physical activity).

Returning to the comparison with a car, our body at rest is like a car with the ignition on at neutral speed – it is not moving, but the engine is running and consuming fuel.


How starving affect our body and behaviour?

Eating less is a great strategy to initially lose unnecessary water stored in the body (metabolic water and water retained by carbohydrates and salt).

But this only lasts for about a week.

Once the excess water has been eliminated, weight loss slows down as fat mass decreases slowly. The low-calorie diets seem to have almost no effect on fat mass reduction because the hypothalamus:

  1. Has reduced energy expenditure, slowing down bodily functions.
  2. Starting to get rid of lean tissue (muscle) because:
    1. It is easier to get energy from muscle (protein) than from fat.
    2. In the case of energy deficiency (lack of food), energy requirements for muscle maintenance are too high.

Our behaviour starts to change – we become sleepy and depressed, but our appetite increases.

After a while, when we return to our “previous” eating habits, the weight returns, but usually in the form of fat rather than lean tissue. These changes happen because:

  1. The body has activated “starvation mode” to store more and more reserves.
  2. Muscle mass has decreased during the diet and it is much harder to regain it than to lose it (it takes a lot of energy and time to grow muscle).

The result is a vicious circle (the Yo-Yo effect): weight is temporarily lost while dieting, but when you start eating normally, the fat in your body increases.


The body works less efficiently in “starvation mode”

Depending on how much you restrict calories and how long you starve yourself, the body will start to prioritise essential bodily functions (such as breathing and heart rate) and slow down non-essential bodily processes such as:

  • Hair and nail growth – they grow more slowly and become brittle.
  • Immunity – it becomes harder for the immune system to fight infections and diseases due to a “lack of resources”.
  • Digestion and hunger regulation – occasional and/or increased hunger, bloating or discomfort in the stomach.
  • Reproductive health – the menstrual cycle may change or stop.
  • Skin health – improper or slow wound healing or premature skin ageing.
  • Bone health – bones become more brittle.

Starvation diets can lead not only to health problems but also to disturbing habits such as restriction or fear of certain foods, excessive exercising and obsession with one’s body weight and size.

In severe cases, prolonged starvation can develop into eating disorders such as anorexia, bulimia or regular overeating (binge eating).


What is the difference between starvation and intermittent fasting?

Fasting is usually defined as going without food for a long time or having highly restricted food intake (usually 450-800 Kcal per day), significantly less than your body needs per day (causing a large calorie deficit).


Intermittent fasting is a pattern of eating that involves alternating periods of “eating” and “fasting”. For example, the most typical pattern is 16:8, which involves an 8-hour eating period and a 16-hour fasting period.

In other words, Intermittent Fasting is not about excessively restricting calorie intake. Yes, you will probably eat less each day, but the calorie deficit will likely be small.


Key takeaways

Starving to lose weight is neither healthy nor sustainable.

Unless you change your lifestyle and eating habits, the weight will return.

If you eat less than your body needs for a long time:

  1. Your body’s metabolism will slow down.
  2. Your body may not function properly.


  1. Your health and mental health will deteriorate.

Yes, you can lose weight by starving, but at what cost?


You will likely regain it, possibly even more than before.


If you want to learn how to lose weight by eating healthily – see a trusted dietician or nutritionist or sign up for my weight loss challenges.

The effect of rate of weight loss on long-term weight regain in adults with overweight and obesity

Very-low-calorie diets

Changes in Energy Expenditure with Weight Gain and Weight Loss in Humans

Metabolic adaptation to weight loss: implications for the athlete

Physiology of weight regain: Lessons from the classic Minnesota Starvation Experiment on human body composition regulation

Persistent metabolic adaptation 6 years after “The Biggest Loser” competition

Metabolic adaptation is an illusion, only present when participants are in negative energy balance

Metabolic adaptation is not a major barrier to weight-loss maintenance

Absence of evidence is no evidence for absence of the phenomenon

Metabolic adaptations to weight loss

Metabolic adaptation is not observed after 8 weeks of overfeeding but energy expenditure variability is associated with weight recovery


Caloric Restriction in Humans: Impact on Physiological, Psychological, and Behavioral Outcomes

Starvation physiology: reviewing the different strategies animals use to survive a common challenge

Eating Disorders in Primary Care: Diagnosis and Management

Current approach to eating disorders: a clinical update

Anorexia nervosa

Predictors of dieting and disordered eating behaviors from adolescence to young adulthood

Dynamic Energy Balance: An Integrated Framework for Discussing Diet and Physical Activity in Obesity Prevention—Is it More than Eating Less and Exercising More?

Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake

Maintenance of lost weight and long-term management of obesity

Defining the Optimal Dietary Approach for Safe, Effective and Sustainable Weight Loss in Overweight and Obese Adults

The Effects of Exercise and Physical Activity on Weight Loss and Maintenance

Exercise Preserves Lean Mass and Performance during Severe Energy Deficit: The Role of Exercise Volume and Dietary Protein Content

Preserving Healthy Muscle during Weight Loss

Intermittent Fasting: Is the Wait Worth the Weight?

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