An unhealthy weight can affect a person's well-being in various ways. That is why many people make a conscious effort to lose excess body weight. But, it turns out that a hidden factor — sleeping patterns — could easily thwart these efforts.

According to data that the National Institute of Diabetes and Digestive and Kidney Diseases have cited, in the United States, more than one in three adults are overweight.

The same is true for obesity — more than one in three U.S. adults live with this condition, which can predispose them to other health problems, including diabetes and heart disease.

An unhealthy weight, however, is not the only problem that threatens the well-being of people in the U.S. and elsewhere. Lack of good quality sleep also causes problems for people around the world.

Although adults need at least 7 hours of uninterrupted sleep per night to feel rested, many individuals are unable to achieve this ideal. Statistics show that in the U.S. alone, in 2017, as many as 36% of surveyed respondents did not feel rested upon waking up in the morning, which suggests that they were not getting enough — or good enough — sleep.

Insufficient sleep, recent studies argue, may affect circulation, aspects of memory, and even our social relationships.

Now, a study that features in the International Journal of Obesity has found a link between insufficient or disrupted sleep and another issue — weight loss. The results showed that overweight people who did not sleep well lost less weight than their peers who had no sleep problems.

The research comes from the Human Nutrition Unit of the Rovira i Virgili University in Tarragona, Spain, and other collaborating institutions.

Good sleep is part of successful weight loss

"The rise in obesity prevalence rates over the past decades parallels an epidemic of sleep disturbances," Prof. Jordi Salas-Salvadó and colleagues write.

"In this context, the PREDIMED-Plus, a new ongoing primary cardiovascular prevention trial based [on] an intensive weight-loss lifestyle intervention program, provides an unprecedented opportunity to examine the 12 month changes in weight and adiposity measures between those participants with short or adequate sleep duration and between those with low or high sleep variability," they continue.

PREDIMED-Plus is a clinical trial that studies the health effects of following a Mediterranean-style diet in a Spanish cohort. The results of the current research are part of this ongoing trial.

In the current research, Prof. Salas-Salvadó and colleagues analyzed the medical data of 1,986 individuals with a mean age of 65 years over the course of a year.

All of these participants were overweight or had obesity at baseline, and they also had metabolic syndrome, a cluster of health risk factors that include high blood pressure (hypertension), increased levels of insulin (hyperinsulinemia), low glucose tolerance, and abnormal levels of blood lipids (dyslipidemia).

For the entire year, these volunteers participated in an intensive weight loss program that included following a low calorie Mediterranean-type diet, boosting levels of physical activity, and participating in behavioral support sessions that aimed to improve habits and lifestyle.

The investigators noted any changes in body weight and body fat (adiposity) throughout the year. They also monitored participants' reported sleeping patterns.

At the end of the study period, Prof. Salas-Salvadó and team found that the participants who, at baseline, reported not sleeping for the same number of hours every night — a phenomenon called high sleep variability — had lost less weight after a year than those who reported a regular sleep pattern; they also experienced less of a reduction in body mass index (BMI).

In addition, the results showed that people who tended to sleep for less than 6 hours each night experienced less of a reduction in waist circumference than those who slept 7–9 hours.

"[T]he findings of our study highlight the importance of sleep characteristics on weight and adiposity responses to lifestyle intervention programs in elders with metabolic syndrome," the researchers conclude.

For this reason, they encourage weight loss programs to monitor participants' sleeping patterns and to consider improving sleep hygiene as part of the intervention:

"Future lifestyle interventions aiming at weight loss should promote adequate sleep and a regular sleep pattern."