Ask a Dietitian: Am I Hungry Or Just Tired?
Are you finding that one portion just isn’t enough lately? Next time you go for seconds, pause and ask yourself – am I hungry or am I just tired? It’s possible that lack of sleep or an irregular sleep pattern is causing you to feel hungrier than when you’re well rested. Here are four of the most common ways that lack of sleep can affect how you eat.
There is increasingly more evidence that lack of sleep may be linked to obesity. Here’s how it works: when our bodies are sleep deprived, our hunger hormone (ghrelin) tends to spike, which can make us feel hungrier than normal despite not actually having expended extra energy. Normally our fullness hormone (leptin) is released by adipose tissue (body fat) to signal to the brain that we have had enough food. But in periods of sleep deprivation, leptin signalling drops. Not only is our hunger hormone heightened, our fullness hormone is also dampened – the perfect storm for overeating.
Another factor to consider in the role of sleep on appetite is that lack of sleep kickstarts a process that raises the blood lipids that are known as endocannabinoids. As the name suggests, endocannabinoids affect the brain in a similar way to marijuana, making eating more enjoyable in general but particularly in the evening. They also tend to increase cravings, especially for junk foods. In addition, a 2012 study found that the increased drive to eat may be particularly powerful in the afternoon. Participants of the study reported increased desire to eat and perceived they could eat more food despite reporting the same fullness as if they’d had a normal night of sleep.
We all already know, but it bears repeating (perhaps as a daily mantra in the mirror each morning), tiredness can significantly affect our ability to exercise self control. In a well-rested state, we are more likely to be able to maintain a healthy eating plan, but in a fatigued state we may not be able to exercise the same level of willpower when it comes to food choices, let alone put in effort to source a healthy, balanced meal.
Impaired glucose metabolism
Another mechanism causing increased hunger when we’re lacking in sleep is impaired glucose metabolism, which is caused when our body struggles to process sugar (glucose) into energy. One study showed that after just six nights of insufficient sleep, participants were not able to effectively break down the glucose they consumed in their diet. These same participants also exhibited a higher blood glucose level after a high-carbohydrate breakfast compared to when they were well rested.
These physiological mechanisms are not the only reason we may tend to eat more in a sleep deprived state, however. Less time spent in bed simply leaves more hours of the day to eat. Many people find poorer eating habits arise in the evening; the later we push back bed time the more time there is for second dinners and snacks, and the later in the night that we eat, the harder it is to fall asleep (and our bodies are more likely to hang on to those calories rather than burn it off).
So if you’re unsure whether you’re hungry or tired, start by addressing your sleep behaviour. Aim for between seven and nine hours of sleep per night and stick to roughly the same bed time and wake time every day – even on weekends. Once you’re in a good swing, watch your hunger levels balance out and eating choices become healthier.
Explore more content like this in our series, Ask a Dietitian.
Health & Performance Collective is the brainchild of Sydney Dietitians Jessica Spendlove and Chloe McLeod. They use their 20 years of combined knowledge and skills as dietitians to work with motivated people to live and perform at their best.