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The most popular — and best — days to start a diet

Is today the day to kickoff new, healthy habits?
/ Source: TODAY

With summer fast approaching, you might be thinking now is the time to get healthy. Well, if you're going to start a new diet or a fitness program, don't put it off until tomorrow... Monday is the best day to start a new diet.

Maligned Mondays are actually days that tap into the "fresh start effect," when we feel like "a new person," ready to take on a change in habits, according to a report.

“On certain days, called temporal landmarks, you just have a different view of yourself,” said Jason Riis, visiting professor at the Wharton School at the University of Pennsylvania and co-author of the report. “You become more forward looking.”

People think, “I am going to be a new person and … I am no longer going to be a part of the path of failure," said Hengchen Dai, a co-author of the paper and doctoral student at Penn. “It’s changing the perception of the self."

To determine these temporal landmarks, the Wharton researchers conducted three experiments: They scoured Google analytics to see when and how often people searched for diet and exercise; Then they tracked the most popular days at the University of Pennsylvania gym; Finally, they examined a website where people made contracts with themselves to change a behavior — they lost money if they failed.

The Wharton researchers didn’t study whether people achieved their goals, but psychologist John Norcross of the University of Scranton said that people who make New Year’s resolutions or quit smoking during events like the Great American Smokeout actually are more successful than expected.

Here are the most popular days for starting a diet, beginning a new workout program, or even switching your 401K into an IRA, according to Wharton researchers.


“Monday is going to be a fresh start,” Dai said. Ann Kearney-Cooke agreed that Mondays motivate people.

“I think it gives an energy surge to people,” said Kearney-Cooke, the psychologist at the Cincinnati Psychotherapy Institute.

Mondays do have drawbacks. People can use all their energy and willpower up early on, meaning they can burn out later in the week. If you fall off track by Thursday, don't wait until Monday for a new start, says Kearney-Cooke.

“The key to change is at the next meal or the next morning, starting over,” said Kearney-Cooke.

There's no evidence of a "bad day" to start a new behavior, but she says don't start something new when you feel low energy and willpower.

Birthdays and anniversaries

Dai realized that she made promises on her birthday and anniversary and wondered if others did, too.

“Every year I make birthday resolutions, I make resolutions on my anniversary. For me, I feel like those are the landmarks that I would like to seize upon,” she said.

It turns out she’s not alone.

The researchers found that day after a birthday many people hit the gym, with the exception of the 21st birthday (too many people are nursing hangovers to consider a workout after that birthday).

“[Birthdays] are meaningful events looking forward,” Riis said, adding that they spur changes in behaviors.

Birthdays also can serve as a time to revisit an earlier goal.

“I think humans like to be reminded ‘Here is an opportunity, go for it,’” said John Norcross, a distinguished professor of psychology at the University of Scranton. “We ask people to start on a day that signifies a new beginning or a meaningfully important date.”

First day of the month

Gym attendance is up in the beginning of the month, according to Google search data. So don't be surprised if workout classes are more crowded or you have to wait for a popular exercise machine.

New season or new semester

Many people make changes at the beginning of the seasons, researchers found. Spring is a time to clear clutter from our lives, or a reminder that bathing suit season is coming. Fall brings the start of a new school year.

One of the times students are more likely to work out is at the start of the semester, Wharton researchers found.

New Year’s

It's a cliché, but people have made New Year’s resolutions since ancient Roman times.

“It is the get out of jail free card … Here is the socially acceptable time to start anew,” said Norcross.

He has studied New Year’s resolutions and found that about 40 percent of people who make them, stick to their resolutions.

“Success rates are better than most people imagine,” Norcross said.

He finds that while a new year gives people an opportunity to think about the future and their future selves, it also helps them reflect on the past and their negative behaviors. He believes people need both perspectives to change.

“Using both sources tends to be associated with success — not just being disgusted [but] looking forward and saying ‘here is my new life.’”

People are more likely to change around the new year because there is more social support and more information available, he added.

But you don't have to wait for New Year's. Patients modify habits on many holidays, including Mother’s Day, Cinco de Mayo, Lent, Yom Kippur or any other holiday that holds meaning for them.


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This story was originally published in 2014.