Many people believe that hunger is related to willpower and learning to control the call of your stomach, but that’s incorrect. Hunger is controlled by two hormones: leptin and ghrelin.
Leptin is a hormone that is produced in your fat cells. The less leptin you produce, the more your stomach feels empty.
The more ghrelin you produce, the more you stimulate hunger while also reducing the amount of calories you burn (your metabolism) and increasing the amount fat you store. In other words, you need to control leptin and ghrelin to successfully lose weight, but sleep deprivation makes that nearly impossible.
Research published in the Journal of Clinical Endocrinoloy and Metabolism found that sleeping less than six hours triggers the area of your brain that increases your need for food while also depressing leptin and stimulating ghrelin.
If that’s not enough, the scientists discovered exactly how sleep loss creates an internal battle that makes it nearly impossible to lose weight.
When you don’t sleep enough, your cortisol levels rise. This is the stress hormone that is frequently associated with fat gain. Cortisol also activates reward centers in your brain that make you want food.
At the same time, the loss of sleep causes your body to produce more ghrelin. A combination of high ghrelin and cortisol shut down the areas of your brain that leave you feeling satisfied after a meal, meaning you feel hungry all the time—even if you just ate a big meal.
And it gets worse.
Lack of sleep also pushes you in the direction of the foods you know you shouldn’t eat. A study published in Nature Communications found that just one night of sleep deprivation was enough to impair activity in your frontal lobe, which controls complex decision-making.
Ever had a conversation like this?
“I really shouldn’t have that extra piece of cake… then again, one slice won’t really hurt, right?”
Turns out, sleep deprivation is a little like being drunk. You just don’t have the mental clarity to make good complex decisions, specifically with regards to the foods you eat—or foods you want to avoid.
This isn’t helped by the fact that when you’re overtired, you also have increased activity in the amygdala, the reward region of your brain.
This is why sleep deprivation destroys all diets; think of the amygdala as mind control—it makes you crave high-calorie foods.
Normally you might be able to fight off this desire, but because your insular cortex (another portion of your brain) is weakened due to sleep deprivation, you have trouble fighting the urge and are more likely to indulge in all the wrong foods.
And if all that wasn’t enough, research published in Psychoneuroendocrinology found that sleep deprivation makes you select greater portion sizes of all foods, further increasing the likelihood of weight gain.
The bottom line: Not enough sleep means you’re always hungry, reaching for bigger portions, and desiring every type of food that is bad for you—and you don’t have the proper brain functioning to tell yourself, “No!”