Can Not Eating Make You Gain Weight?

Sometimes if we don’t have the money or the time to be going out and organizing healthy nutritional meals to help with our calorie intake, the simple answer can be to just not eat at all, at least until we feel it is absolutely necessary.

While there are certainly benefits for not eating for a very short period of time, this method is definitely not optimal in the long run as it can negatively affect other underlying conditions such as diabetes and cardiovascular disease.

Can Not Eating Make You Gain Weight?

However, there are many who have also claimed over the years that not eating can also actually add on more weight rather than helping burn calories off.

To find out how true this claim is, we have taken a deep and detailed look into how starving the body of calories works, and if it can actually result in a weight gain.

Will I Gain Weight By Not Eating?

This is very much dependent on how long you go without eating as while initially in the short term you can actually lose a lot of weight from eating nothing, in the long term our body can adapt to the lack of necessary nutrients and calories which can make putting on weight far easier.

There however are a few ways that not eating can inadvertently lead to gaining more weight when practiced for an extended period of time.

Slower Metabolism

The key reason for weight gain when not eating is due to the metabolism which will slow down drastically after long-term calorie deprivation of at least a few days of not eating entirely.

During this time, the body will begin to use stored fat as its primary source of energy while also reducing and slowing down our resting metabolic rate.

With a slower metabolism, the body burns calories at a much slower rate since it is trying to hold onto as much energy as possible to fuel the body enough so it can function again.

Therefore while the act of not eating itself will not lead to a weight gain, when practiced for too long it does mean that the body will have a much harder time burning calories when you start eating again, so it really is up to you to weigh out the short and long term pros and cons.

Calorie Deficit

Experiencing a calorie deficit is actually the way we lose weight by expending more calories through exercise and eating less in general, so it is actually a very positive term.

The issue with experiencing a severe calorie deficit after a prolonged non-eating period however is that while it can result in a tremendous amount of weight loss in the short term, recent research has found that our body craves a tremendous amount of calories to escape out of it’s ‘starving’ mode which can therefore easily lead to an excessive calorie intake when we start eating again which is caused by the increased hunger and feeling ‘free’ from the calorie deprivation.

Other Effects On The Body When Not Eating

While you will therefore not gain weight directly from not eating, it can lead to knock-on effects that can result in you gaining more weight than you had before and overtaking many calories and fat lost during the fasting period.

There are however some other side effects that can result from not eating that should be noted if you are thinking of trying it for the first time.



Feeling weak, unfocused and fatigued can occur if we simply don’t have breakfast in the morning to get us ready for the day, so if we choose not to eat completely for the day, the body will receive no energy from calories which it needs to function properly and keep us awake and working at our best.

This can impair not just our mental activity, but also physically as our body won’t have enough energy to perform as it normally would.

Hair And Nail Loss

If our body has an extreme lack of minerals, proteins and fatty acids it can lead to a lot of abnormalities including hair loss and our nails becoming brittle.

These abnormalities usually occur if the body has experienced an extreme calorie deficit for an extensive period, so fasting for a short while will not lead to these changes right away.

Impaired Growth

If you are a bit younger and are going through puberty, good nutrition and a steady calorie intake is vital for leading to a good and healthy development of the body, therefore not eating can seriously prevent bones from growing and becoming strong which can lead a person to be much weaker as they grow older.

Is Not Eating Still Good For Losing Weight?

Not eating at all for a very short period of time can definitely help in losing weight very quickly, though it should not be relied on every time you want to burn a few calories.

Research from scientists on Global News have stated that on a day where you don’t eat for the entire 24 hours, you are guaranteed to lose half a pound of non-water weight which essentially refers to body fat.

After around 8 hours of not eating, your body will start using the stored fat as its energy source, so you may actually feel fine by midday until you go to bed, however always make sure to eat as soon as you wake up since not eating for more than a day can start to lead to unwanted bodily effects.

It is also heavily advised that instead of not eating at all, you choose a fasting method which just allows you to eat at certain points such as every 8 hours for example.


While not eating will not directly and immediately lead to the body gaining weight, it can lead to this when you do start eating again, so while it can be an effective method to use for a day, the more sustainable method of weight loss would be creating a fasting method where you can eat at certain points.

Jenna Priestly