Weekends slow weight loss, researchers find

July 1, 2008

Saturday can be the worst enemy for our waistlines, according to researchers at Washington University School of Medicine in St. Louis. They found that study subjects on strict diet and exercise programs tend to lose weight more slowly than expected because they eat more on weekends than during the week. The investigators report their findings in the advance online publication of the journal Obesity.

Past research had confirmed that people tend to gain weight during the holidays, particularly between Thanksgiving and New Year's, but this is the first study to carefully monitor daily body weight, calorie intake and calorie expenditure for several weeks throughout a year, and to demonstrate that increased caloric intake isn't just a problem during the holidays. It also happens on most weekends.

"We thought weekends would present a problem for some people attempting to lose weight, but the consistency of our finding before and during the interventions was surprising," says first author Susan B. Racette, Ph.D., assistant professor of physical therapy and of medicine. "Subjects in the diet group lost weight during the week, but over the weekend, they stopped losing weight because they were eating more."

Racette's team followed 48 adults between the ages of 50 and 60 who took part in the CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) study. Body mass index (BMI) ranked subjects as overweight or healthy weight when the study began. None were classified as obese.

Following earlier studies demonstrating that mice and rats live longer, healthier lives when on a calorie restricted diet, the CALERIE study is designed to determine whether taking in fewer calories over a long time period will slow down or reverse some of the common markers of aging and disease.

"But rats don't have weekends the way people do," Racette says. "On weekends, human lifestyle patterns can be very different. People have social events, parties to attend, and if they have children who play sports, they might be at fields all day long, relying on concession stands for food."

Study participants were divided into three groups: the first lowered their daily calorie intake by 20 percent, a second increased daily physical activity by 20 percent, and a third, control group did not change diet or activity levels. All three groups were monitored for one year. They kept food diaries, tracked exercise with accelerometers and were weighed regularly. Racette says people in the study didn't always realize they were eating significantly more food on weekends.

"It was surprising how consistent the findings were," she says. "We also were surprised by the dramatic way in which weekends continued to slow weight loss throughout the course of the study."

Before the interventions began, the researchers established "baselines" for each study participant's exercise and eating habits. This pre-intervention data determined that participants consumed the most calories on Saturdays. An average of 36 percent of their total calories came from fat on Saturdays, but less than 35 percent came from fat during the rest of the week. The typical weekend weight gain before the diet and exercise interventions began would have led to an average increase of 9 pounds a year.

When study participants were asked either to cut calories by 20 percent or to increase activity by a like amount, the pattern remained the same. Those in the calorie restriction group took in more energy on Saturday. Those in the exercise group ate more on both Saturday and Sunday. As a result, people in the calorie restriction group stopped losing weight on weekends, and those in the exercise group actually gained weight on weekends.

"People on diets often don't lose as much weight as we would expect, and this finding helps to explain why," she says.

As the researchers move into the second phase of the CALERIE study, looking at more subjects over a longer period of time, they now recommend that participants weigh themselves daily in order to be more aware of their patterns of weight loss and weight gain, particularly on weekends. For those not in a research study, she recommends moderation and careful planning to avoid weekend pitfalls.

"Planning ahead can't be emphasized enough," Racette says. She recommends packing healthy food if you're running errands, eating a little something so you aren't starving when you arrive at a party, even packing a light lunch before going to the kids' ballgames so that you have a choice other than junk food at a concession stand.

"In addition, she says, "paying closer attention to portion sizes can enable a person to enjoy the weekend without sabotaging weight-control efforts."

Source: Washington University

Explore further: Drinking alcohol key to living past 90, study says

Related Stories

Drinking alcohol key to living past 90, study says

February 20, 2018
Cheers to life—seriously.

Researcher sheds light on health effects of not getting enough rest

March 7, 2018
This weekend's change to daylight saving time means an extra hour of light in the evening. The shift is a milestone on the way to barbecues and beach trips, but adjusting to the loss of an hour's sleep can be difficult, especially ...

Efforts to track food intake on smartphone app impacted by day of week but not season of year

January 8, 2018
Dietary self-monitoring is a key component of successful behavioral weight loss interventions and is essential for facilitating other behavior change techniques (eg, setting goals, providing behavioral feedback). Few studies, ...

Five tips to bounce back to a leaner, healthier body this new year

January 5, 2018
Everyone loves the holiday season. Spending time with family and friends, sounds of laughter throughout the house, mouthwatering smells radiating from the kitchen, feasting on holiday specialties … and feeling extra padding ...

Turn your commute into a daily workout

January 24, 2018
(HealthDay)—Commuting by car doesn't just try your patience.

The Medical Minute: Don't overdo it, you weekend warrior

August 18, 2011
There are many benefits to exercise. Exercise not only helps prevent a variety of medical disorders -- including heart disease, high blood pressure, diabetes, obesity, osteoporosis -- but it is increasingly recommended for ...

Recommended for you

Whether sustained or sporadic, exercise offers same reductions in death risk

March 22, 2018
For decades, Americans have been inundated with a confusing barrage of messages about how best to counteract the health risks of sedentary lifestyles: walk 10,000 steps a day; do a seven-minute workout from a phone app; flip ...

Tai chi as good as or better than aerobic exercise for managing chronic pain

March 21, 2018
The ancient martial art of tai chi has similar or greater benefits than aerobic exercise for people with the chronic pain condition fibromyalgia, finds a trial published by The BMJ today.

Study: Poor health is a less common cause of bankruptcy than commonly thought, but it brings other economic woes

March 21, 2018
A team of researchers led by an MIT economist has found that medical expenses account for roughly 4 percent of bankruptcy filings among nonelderly adults in the U.S.

Study finds bad sleep habits start early in school-age children

March 21, 2018
Bad sleep habits in children begin earlier than many experts assume. That's the takeaway from a new study led by McGill University researchers. The findings suggest that official sleep guidelines for young school children ...

Medical expansion has improved health—with one exception

March 21, 2018
While Americans debate the rising cost of health care, a new study of 30 countries over 27 years found that medical expansion has improved overall health - with one major exception.

Forgetting details, getting the gist may prompt false memories in older adults

March 21, 2018
Older adults often complain about forgetting, but Penn State psychologists suggest that another problem may be misremembering.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.