People often weigh less in the morning because they lose water throughout the night as they breathe and sweat. That said, individuals do burn calories during the night. However, the loss of water weight is more significant than the loss of fat.
While people may not burn a lot of fat from sleep alone, sleep is important for weight loss.
For example, a 2018 study found that sleep disruption can slow fat loss and make it more difficult for a person to lose weight, especially when they are following a restricted-calorie diet.
Read on to learn more about losing weight while sleeping, including how it occurs and how sleep disruptions may impact weight loss.
When individuals lose water as they sleep, they experience insensible water loss, which is a loss of water through physiological processes such as breathing, sweating, and excretion.
Health experts say that water loss from breathing and sweating alone can account for up to 83% of weight loss during sleep.
The amount of water that individuals lose during the night will vary because not everyone has the same metabolic rate.
Sleep disruption can affect many biological processes, including hunger.
One 2017 review reported that people who experienced altered sleeping patterns had generally larger appetites and consumed more calorie-dense meals than those who did not.
This finding suggests changing sleep times could have consequences on a person’s weight management.
A 2016 study found the body mass index of nursing professionals increased when they switched from day to night shifts.
Additionally, a lack of sleep can also increase the risk of metabolic syndrome, where a cluster of risk factors can occur simultaneously. When several of these risk factors occur, the likelihood of developing cardiovascular disease, stroke, and diabetes increases.
These risk factors include:
- excess fat around the abdominal area
- low levels of high-density lipoprotein, or “good” cholesterol