Nearly everyone gradually loses weight during the week and then gains it back over the weekend, a team of American and Finnish researchers reported.
"Almost to a person, we weigh the most Sunday night and we weigh the least Friday morning," said study co-author Brian Wansink, a professor of consumer behaviour at Cornell University and author of the book Slim By Design.
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Weaker weekday compensation
But people who successfully lose weight and keep it off are those who maintain healthy eating habits during the week, the researchers found.
Those who consistently lost weight in the study tended to compensate more strictly during the week for their weekend weight gain, the researchers said. Their weight began decreasing immediately on Monday and continued downward until Friday, while people who tended to gain weight showed a weaker weekday compensation for the weekend's indulgences.
"The ones who are big winners are those who lose a little bit of weight from Monday to Tuesday to Wednesday to Thursday," Wansink said.
The study, published online in the journal Obesity Facts, involved 80 people aged 25 to 62. Researchers asked them to weigh themselves before breakfast every day for anywhere from two weeks to nearly a year.
The study found that everyone – whether they were losing or gaining pounds – had fluctuation in their weight during the course of a week.
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Pattern and rhythm
Wansink said he believes this occurs because weekdays are more regimented, making it easier for people to watch what they eat. Meanwhile, the weekends offer many temptations.
"There's a lot of variety and fluctuation in what you do over the weekend, but the weekdays have a pattern and a rhythm," he said.
But tracking weight day by day showed that what is a steep weekday decline for weight losers appears to be a gentler curving slope for people experiencing weight gain.
People who lost weight reached their highest weight of the week on Sunday and Monday three-fifths of the time. They hit their lowest weight on Friday or Saturday at the same rate.
Weight gainers had no such clear pattern. Although the overall trend was downward during the week, individual minimum and maximum weights did not systematically appear on specific days.
It's about the journey
Registered dietitian Joy Dubost said the study "confirms suspicions that many dietitians have had for a while that your weight does fluctuate and it's OK to forgive that because fluctuation occurs naturally."
Many people will adopt a healthy eating plan and then abandon it in frustration when they see they put on a little weight over the weekend, she said.
"This shows it truly is about the journey, rather than the one-time splurge where you gain a couple of pounds," said Dubost, who practices in Washington, DC., and is a spokeswoman for the Academy of Nutrition and Dietetics.
"If you're too restrictive and you don't allow any flexibility and you don't allow those short-term splurges, that may not set you up for success long-term," she said. "People who are successful at weight loss are those who see it as a lifetime journey."
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