You have rethought how much you eat and the balance of your meals, and you keep up with exercise. Yet when your weight still will not come down as you hoped, it is easy to start thinking, “Should I eat even less?” or “Am I not exercising enough?”
However, there is another factor that is easy to overlook: sleep.
Recent research suggests that lack of sleep does not just make you drowsy the next day, but may also affect weight management through appetite and daytime activity levels.
People Who Sleep Less Have About a 30% Higher Risk of Obesity
A study published in 2025 in the international journal Clinical Obesity pooled 18 systematic reviews and meta-analyses that examined the relationship between sleep duration and obesity.
It reported that adults with short sleep duration had about a 30% higher risk of being overweight or obese than adults who got enough sleep. Specifically, the relative risk was 1.30, with a 95% confidence interval of 1.17 to 1.44.
However, this figure does not mean that “if you lack sleep, you will definitely gain weight.” It shows an association, drawn from multiple studies, that people who sleep less are more likely to become obese.
On the other hand, newer experimental research has also confirmed that actually shortening sleep may change body weight.
What Happens After 6 Weeks of Sleeping 90 Minutes Less a Day?
In July 2026, a pooled analysis of randomized trials examining sleep loss and weight change was published in the Annals of Internal Medicine.
The study compared 6 weeks of sleeping 1.5 hours less each night than usual with 6 weeks of normal sleep.
As a result, the group that slept less gained an average of about 0.45 kg over 6 weeks. In premenopausal women in particular, an increase in fat mass was also observed.
You may feel that 0.45 kg is not a big change. However, this was not an experiment in which participants were told to overeat; it was the result of observing what happened mainly when sleep time was changed.
It can be said that this study shows that even a small lack of sleep, if it continues as a daily habit, may affect weight management.
Why Does Lack of Sleep Make It Easier to Gain Weight?
There is more than one mechanism linking lack of sleep and weight gain.
When you do not get enough sleep, you feel more tired the next day and may unconsciously move your body less. Small changes, such as taking the elevator instead of the stairs, staying in more or spending more time sitting, can add up and may lower the energy you burn.
Lack of sleep also affects appetite. Past experiments have reported that restricting sleep increases ghrelin, a hormone that stimulates appetite, and that this change was associated with how much people ate when they could eat freely.
On sleepy days, you may crave sweet or fatty foods, and staying up late can also simply create more opportunities to eat.
In other words, lack of sleep may make weight management harder through several pathways, such as
• Appetite becoming stronger
• A tendency to choose high-calorie foods
• Longer hours during which you can eat
• Daytime activity levels tending to drop
and more.
Does Sleeping Longer Mean Eating Less?
There is also research on what happens when sleep improves.
In a 2022 randomized controlled trial conducted by the University of Chicago and others, overweight adults who usually slept less than 6.5 hours a day received individual coaching to help them sleep longer.
In the group that extended their sleep, sleep time increased by an average of about 1.2 hours, and even though they were not told to restrict their diet, their daily energy intake fell by an average of about 270 kcal.
These results also suggest that sleep is not separate from diet and exercise, but one of the foundations that keeps appetite and daily behavior in balance.
If You Are Working Hard on Diet and Exercise, Review Your Sleep
To lose weight, you basically need to burn more energy than you take in.
So diet and exercise remain just as important.
However, when you are short on sleep, it becomes harder to control your appetite and to keep exercising in the first place. If you are sticking with diet and exercise but not seeing results, it may be worth checking sleep habits like these before trying even harder:
• Are your bedtime and wake-up time very different on weekdays and days off?
• Are you getting the sleep you need?
• Are you looking at your smartphone right up until bedtime?
• Have late-night meals, caffeine or drinking become a habit?
• Do you keep waking up still feeling tired?
It is important to pay attention not only to how long you sleep but also to the quality of your sleep, such as “waking up many times during the night” or “not waking up feeling refreshed.”
Can a Dry Head Spa Be a Step Toward Better Sleep?
At La HEAD, too, our guests sometimes share comments such as
“I slept well on the day of my treatment”
“I fell asleep easily”
“I woke up feeling refreshed the next morning”
and more.
There is research reporting that people with chronic insomnia symptoms who received a relaxation massage before bed showed improvements in sleep-related measures. A small study has also suggested that head massage may increase parasympathetic nervous system activity.
However, these studies alone do not allow us to conclude that a dry head spa improves insomnia or obesity. The types of massage and the participants also differ, and more high-quality research is needed.
Even so, we believe that caring for tension in the head, neck and shoulders, and spending time without thinking about anything in a space with gentle lighting, soothing scents and calm quiet, can be one way to help switch your mind and body into rest.
When it comes to dieting, we tend to focus only on “eating less” and “exercising more.”
However, to support your diet and exercise, sleep cannot be taken lightly.
If you are not seeing results, before deciding that you are not trying hard enough, why not start by looking back at your daily sleep?