US Researchers discovered women who wrote down what they eat lost six pounds (2.7kg) more than those who did not record, concluding that old-fashioned calorie counting was more important than the type of diet.
Scientists also found that skipping meals proves counter-productive, as it made dieters resort to eating unhealthy snacks instead. Those who skipped meals lost eight pounds less (3.6kg) than those who did not, The Telgraph reported.
The study team looked at dieting methods among 123 overweight women aged between 50 to 75.
"For individuals who are trying to lose weight, the number one piece of advice based on these study results would be to keep a food journal to help meet daily calorie goals," Dr Anne McTiernan, from the Fred Hutchinson Cancer Research Centre in Seattle, said.
"It is difficult to make changes to your diet when you are not paying close attention to what you are eating," McTiernan said.
The study is published in the Journal of the Academy of Nutrition and Dietetics.
"All the evidence shows that people who use a food diary not only lose more weight but also keep the weight off." Elaine Mealey, from the British Dietetic Association, agreed.