A "tortoise and the hare" approach to weight loss is most likely to succeed in the race to slim, research has shown.
As in the well known Aesop's fable, consistent plodding appeared to be more effective than a mad dash to the finish line.
The study of 183 participants found that "hares" most likely to crash diet their way to slimness lost less weight over two years than "tortoises" who shed a consistent number of pounds each week.
Researcher Dr Emily Feig, from Drexel University in the US, said: "It seems that developing stable, repeatable behaviours related to food intake and weight loss early on in a weight control programme is really important for maintaining changes over the long term."
Obese and overweight individuals were enrolled into a year-long weight loss programme based on meal replacements and behavioural strategies such as self-monitoring, calorie counting and increased exercise.
Bigger weight fluctuations in the first six and 12 weeks led to poorer weight control 12 months and two years later, the results published in the journal Obesity showed.
For example, a person who lost four pounds one week, regained two pounds the next week, and then lost one pound a week later, fared worse that someone who shed one pound per week consistently for three weeks.
The scientists did not explore the reasons why some participants' weight varied more than others. But previous research has shown that trying to slim too fast can set up a yo-yo cycle of crash dieting and fluctuating weight.
Chief investigator psychologist Professor Michael Lowe, also from Drexel University, said sticking to weight loss goals was important, even if progress was slow.
He said: "Settle on a weight loss plan that you can maintain week in and week out, even if that means consistently losing three quarters of a pound each week."