It is normal to feel hungry occasionally between meals.
But those who feel like their stomach is constantly rumbling between breakfast, lunch and dinner may wonder why they are always hungry.
According to registered nutritionist Rob Hobson, this can be the cause of insufficient sleep, stress and even overeating chips, cakes and sweets.
According to registered nutritionist Rob Hobson, this can be the cause of insufficient sleep, stress and even overeating chips, cakes and sweets.
Revising your diet can increase hunger levels in some cases.
For example, those who strip away meat, dairy, and eggs by going vegan may be left with a rumbling stomach.
“Although you eat more food, it's low energy,” Mr Hobson explained of the meat-free diet.
Vegetables, grains, nuts and fruit form the basis of a vegan diet.
But this diet dramatically reduces the nutrients and proteins that a person is used to consuming from animal products, which take longer to digest and therefore suppress appetite for longer.
Not getting enough sleep can also stimulate your appetite.
This is because a good night's sleep is essential for promoting a healthy balance between the hormones that control appetite, Mr Hobson said.
In particular, too little sleep can increase levels of ghrelin – which is secreted in the stomach and signals to the brain when to eat – and decrease levels of leptin, which is the cause of feelings of fullness.
Chronic stress can also cause feelings of hunger.
In the short term, stress triggers a fight-or-flight response, which signals the adrenal glands to release adrenaline. This temporarily suppresses hunger.
However, if stress continues, the glands located on top of the kidneys release cortisol. This hormone stimulates appetite, Mr Hobson said.
Some medications, such as antidepressants, can also be the cause.
That's because the drugs increase the amount of serotonin in the brain, which, over a long period of time, can reduce the number of serotonin receptors, called 5HT2C, on the cell surface.
Studies show that blocking this receptor can increase cravings for carbohydrate-rich foods, such as bread, pasta and pastries, and lead to weight gain.
Moreover, an unhealthy diet can also increase hunger levels.
Even if it is a large portion of pizza, hamburger and fries or ice cream, these junk foods are low in fiber and high in carbohydrates.
This combination, according to Mr Hobson, can result in a sudden drop in blood sugar levels, signaling that the body needs more food.
In contrast, a meal high in protein and healthy fats slows the release of sugar into the bloodstream, leading to feelings of fullness between meals.
Counter-intuitively, snacking out of boredom can lead to people feeling hungrier and falling into a “vicious cycle of eating”, Mr Hobson said.
People often turn to fast-digesting foods that are low in fiber and high in sugar when looking for a snack, such as cakes, cookies and sweets.
Mr Hobson said: 'These foods simply add extra energy to the diet when it is not needed, and the person is not necessarily hungry or in need of food.
'These fast-digesting carbohydrates accentuate the drop in blood sugar levels and this can contribute to more intense feelings of hunger, mood swings and usually cravings for more of the same type of food, creating a vicious cycle of eating.'
As a result, frequent snackers may lose the ability to tell when they are actually hungry because they are “always eating,” he said.