When Is the Best Time to Start a New Diet?

New Year’s diet resolutions are popular for a reason: You can thank a phenomenon called the “fresh start effect.” 

Research shows that people are more likely to pursue a goal when they start on a landmark date (such as the first day of a new year) than on a random date. Why? Because landmark dates help mark the passage of time, allowing us to separate our past selves from our aspirational future selves. 

“This means that the start of a week, month, or even a new year can psychologically symbolize a new beginning, thereby providing an ideal opportunity to kick-start healthier habits or work toward new objectives,” says Kelsey Costa, RDN.

In other words: new year, new you.

For some, that “fresh start” seems to do the trick. In a study published in the journal Obesity in May 2023, of the more than 85,000 people at risk for type 2 diabetes, those who kicked off a weight management program in January lost 12 to 30 percent more weight than those who started the program at other times of the year. 

Still, January 1 may not be the ideal start date for everyone. “Some people may feel additional stress from the pressure to lose weight at the start of the year, which also coincides with short, gloomy days and colder weather,” says Marissa Toussaint, MD, a board-certified obesity medicine physician. When combined, these factors can quickly sap your motivation to stick with healthy diet resolutions. 

If your New Year’s diet resolutions never seem to stick, consider other times that experts say can be good for starting a new diet. 

Mondays

As the first day of a new workweek or school week, Monday offers the perfect opportunity to start a new course of healthy eating. 

Practically speaking, Monday can be a convenient start date if you grocery-shop over the weekend, notes Catalina Ruz, RD, who works with Top Nutrition Coaching. This gives you the opportunity to prepare healthy meals for the upcoming week. Having healthy meals ready to go can make it easier to follow your diet when you get busy with work and family commitments during the week. 

Mondays also offer more “resets” than other landmark dates. Suppose you resolve to change your eating habits on January 1 and slip up on January 14. In that case, you may be tempted to throw up your hands and wait for another landmark date to restart your diet. But Mondays give you a “fresh start” every seven days. 

Birthdays

Birthdays are like your personal New Year’s Day. They signal the beginning of a new year of your life, leading you to reflect on the past year and any progress (or lack thereof) you made toward your health goals, Costa notes. 

If your birthday fuels motivation for change, it can be a great time to think about your nutrition, Ruz adds. If not, don’t force it!

Life Events

“Life events, such as a milestone achievement, getting married, or even changing jobs, can often catalyze positive dietary changes,” Costa says. 

For example, scoring a raise or promotion at work can boost your confidence, leading to a renewed commitment to your personal health. “Similarly, marriage often triggers a reassessment of lifestyle habits, as the prospect of building a life together can motivate individuals to adopt healthier eating habits for long-term health,” Costa notes. 

Having an important event like a wedding or vacation on the calendar can also motivate you to start your weight loss journey. Plus, it gives you a target date to aim for, which can help you plan your efforts accordingly.

Change of Seasons

For some people, the change of seasons spurs a need for change in other areas of their lives. Spring is traditionally a time of renewal and growth, inspiring people to “spring-clean” their homes — and pantries. Meanwhile, summer brings warmer temperatures and longer days, which may make it easier for some to be physically active. “There’s also a greater abundance of seasonal produce, allowing more variety and enjoyable meal options,” Dr. Toussaint notes. 

A change of seasons may also coincide with other transitions, such as kids starting school in the fall. These transitions may give you more time or energy to spend on your nutrition.

The Secret to Lasting Diet Changes

Landmark dates such as New Year’s can be successful diet start dates. However, it takes more than a “fresh start” for lasting weight loss. “Sustainable and healthy diet changes aren’t always the dramatic overhauls we envision,” Ruz says. “Real change is often more about gradual improvements than a complete transformation.”

Costa suggests harnessing the momentum of landmark dates to reassess your nutrition habits, set achievable goals, and seek professional advice (if needed). Then, work on incorporating healthier food choices into your routine.

It’s also worth noting that you shouldn’t have to wait for a birthday, life event, or other landmark date to begin a diet. “Sometimes, the most opportune time to start making healthier eating choices is today,” Ruz says.
 

Editorial Sources and Fact-Checking

• Dai H, Milkman KL, and Riis J. Put Your Imperfections Behind You: Temporal Landmarks Spur Goal Initiation When They Signal New Beginnings. Psychological Science. November 5, 2015. 
• Koutoukidis DA, Barron E, Stevens R, et al. Association Between the Month of Starting a Weight Management Program and Weight Change in People at High Risk of Type 2 Diabetes: A Prospective Cohort Study. Obesity. May 8, 2023.