How weekend eating adds up

By Terri Coles

TORONTO (Reuters) -- People regularly overeat on the weekend, which can sabotage their weight loss efforts and lead to a gain of nearly 10 pounds by the end of the year, new research shows.

Participants in a Washington University School of Medicine study consistently ate more from Friday through Monday than they did during the week, with Saturday being the worst day for overeating. Previous studies had confirmed what anyone faced with a holiday dessert buffet could tell you: special days, especially between Thanksgiving and New Year's, often led to weight gain. But the Washington University study, funded by the National Institutes of Health and published in advance in the online edition of the journal Obesity , is the first to show that people eat more calories on most weekends of the year.

"This is just one of those many factors that can hinder weight loss or weight control efforts," said Dr. Susan Racette, the study's lead author and an assistant professor of physical therapy and medicine at Washington University in St. Louis.

The study followed 48 adults aged 50 to 60 as part of the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) study, which is looking at the possible health benefits of a calorie-restricted diet, shown to reduce some common markers of aging and disease in animal studies. The participants all had a body mass index (BMI) that placed them in the normal or overweight categories at the start of the study, and none were obese.

Participants were put into one of three groups. The first kept their diet and activity levels as is, the second reduced daily calorie intake by 20 percent, and the third increased daily exercise by 20 percent. A careful daily record of their food intake, activity levels and weights were kept for one year, Racette said.

"The main thing we found was that before interventions began, when people were just doing their own thing, they consistently gained weight on weekends," Racette said. Some of that gained weight -- an average of 0.4 pounds on the weekend across all study subjects -- would be lost again during the week, but not all of it, leading to cumulative weight gain over time.

"If someone is not really trying to follow any particular diet prescription," she said, "it could lead to an almost nine-pound weight gain at the end of the year if they repeated this pattern every weekend."

Those in the intervention groups showed a slowdown in progress on the weekends as well, due to extra calorie consumption. The participants in the reduced-calorie group lost weight during the week, but stopped losing on weekends because they were eating more, Racette said. Those in the increased-activity group kept up their exercise through the entire week, but though they lost weight during the week, they gained it on the weekend because they didn't burn enough calories to make up for the extra food they consumed.

Over time, that pattern slows down weight loss progress for people who are following a particular diet or exercise plan, Racette said, which could lead to frustration when the pounds don't come off as quickly as expected. "They're working really hard during the week, but then they allow themselves to be more casual on weekends, and they end up being a lot more casual," she said. "If it were to continue every weekend, then it could lead to substantial gain over the year because they're not completely making up for it during the week."

The main culprit for the increased calories seemed to be fat -- an average of 36 percent of the study participants' calories came from fat on the weekends, with less than 35 percent coming from fat during the week. The kinds of foods that people often eat on weekends -- convenience foods and junk foods -- are often high in fat, and fat is higher in calories than protein or carbs.

It occurred to the researchers that water retention due to excess sodium intake could be behind the higher numbers on the scale on the weekends, Racette said, but evaluation of the data showed that there wasn't a significant increase. CALERIE follows older people, she pointed out -- younger people may have a weekend diet with more alcohol and high-sodium foods, and that could increase the effect on weight.

The key to keeping the risk of weekend weight gain in check is consistency, Racette advised. Being aware of what you're eating on the weekends and setting yourself up for healthy choices by planning ahead can help you maintain your weight or keep weight loss going through the entire week. The study participants had to weigh themselves daily, which increased their awareness of small weight changes before they became big ones. They also kept a careful record of what they ate; keeping a food diary can help you see patterns in your diet, she said.

During holidays and weekend get-togethers, plan to enjoy a couple favorite treats and ignore the rest. Watch portion sizes, and if the event is a potluck, bring a healthy dish so you know there will be at least one available. And it's helpful to move your focus at events away from the food and towards the social aspect, Racette said.

Some diets advocate having a day during the week where anything goes, as a means to avoid temptation on the other six days. That strategy is not a bad one, Racette said.

"Certainly, having a little more freedom once a week can be helpful as long as you don't take that to an extreme," she said.