(Reuters Health) - Dieters who lose varying amounts of weight each week may not shed as many excess pounds as people who consistently lose the same amount week in and week out, a U.S. study suggests.

Researchers examined data on183 overweight and obese adults who participated in a weight loss program with meal replacements provided along with goals for calorie monitoring and exercise.

After two years, the dieters who had the most consistent weight loss during the first three months of the program shed more excess pounds than the people who initially had more fluctuation, researchers report in the journal Obesity.

While the study can’t explain whether or how consistency in weekly weight loss might contribute to success, it’s possible that different approaches to dieting played a role, said study co-author Michael Lowe, a psychology researcher at Drexel University in Philadelphia.

“Those who lose weight steadily may have had more consistent eating and exercise habits before they joined our program and continued with that pattern as they cut back on calories and exercised more,” Lowe said by email.

“Those with more variable patters may be trying to lose weight as quickly as possible - so they sometimes have big weight losses, but this leaves them starving and unable to stay on their diet for a week or so,” Lowe added. “They regain some of their weight, get upset, and try to lose as much as they can again.”

At the start of the study, participants were 51 years old on average and typically obese. The majority were white, and most were women.

Overall, participants’ weekly weight loss tended to vary by about 1.09 pounds during the first six weeks and by 1.33 pounds during the first 12 weeks of the study.

Women tended to be more consistent dieters than men, with less variation from one week to the next at both six weeks and 12 weeks.

The researchers found that higher weight variability during the initial six and 12 weeks of weight loss treatment predicted poorer subsequent, long-term weight control at one year and at two years.

For example, someone who lost four pounds one week, regained two and then lost one the next tended to fare worse than someone who lost one pound consistently each week for three weeks.

Interestingly, individuals who reported lower emotional eating, binge eating and preoccupation with food at the start of the study showed higher weight variability and less weight loss overall.

This suggests that initial weight change, rather than relationships with or behaviors toward food, is much more important in predicting who will succeed in weight loss and maintenance, the authors conclude.

It’s also possible that variation in weight loss from one week to the next slows down overall weight loss, making it harder for people to achieve long-term weight loss goals, said Susan Roberts of the USDA Nutrition Center at Tufts University in Medford, Massachusetts.

“So people who are on their program some weeks but not others will inevitably lose less weight because you can’t really catch up in the sense of making up bad weeks,” Roberts, who wasn’t involved in the study, said by email. “At best, you can only get back on track.”

Participants who had more consistent results might also do more thorough job of tracking what they eat and how much they exercise, said Dr. Anne McTiernan of the Fred Hutchinson Cancer Research Center in Seattle.

“Perhaps the people with variability are having a harder time being careful about counting calories, watching what they eat, and staying active,” McTiernan, who wasn’t involved in the study, said by email. “Slow and steady wins the race.”

SOURCE: bit.ly/2vGXuCR Obesity, online August 28, 2017.