Dieters are more likely to stick to their New Year's resolution if they use an app that daily monitors how much they eat, a new study found.
After the excesses over Christmas many struggle to maintain their diet as they rely on self control and haphazardly recording what they ate.
Most dieters admit they do well through the week but as the weekend approaches let go and overeat, have more fatty and high calorie foods and a worse diet.
Yet tracking what food you eat and how many calories it contains in real time can help people stick to their diet regime, especially avoiding overindulging on the weekend.
Assistant Professor of Exercise Science Christine Pellegrini at the University of South Carolina, explained: "Daily dietary self-monitoring generally entails tracking all foods and drinks consumed, the portion size of each item, and the corresponding calorie and fat gram totals.
"Ideally, this recording occurs as foods are consumed; yet in practice, many people do not record near the time they ate.
"Awareness of caloric intake is expected to align eating behaviours with goals to create a negative energy balance and facilitate weight loss.
"Patterns in short-term dietary intake have also been identified, including consuming more calories and fat on the weekends, particularly among those who are overweight or obese, of high income, or aged 18 to 64 years.
"In addition to these increases in calories and fat, diet quality is poorer on the weekends.
An app a day
"The increase in caloric and fat intake corresponds with weekly fluctuations in weight: weight is higher on Sundays and Mondays and decreases as the end of the week nears.
"In contrast to the increase in caloric consumption and body weight, self-monitoring was recently found to be less frequent on weekends than weekdays.
"The holidays are another time when increased caloric intake and weight gains of 0.4 to 0.7 kg are seen."
In the study 31 obese adults aged 18 to 65 were split into three groups for the six month study.
One self-monitored their dietary intake on the ENGAGED study smartphone app, one were put on a weight loss programme and one group were left to diet on their own.
The app contained a database of over 50,000 generic and name brand foods with their nutritional values and users given visual feedback on calories and fat grams consumed.
All groups were given a seven per cent weight loss goal, encouraged to meet a daily calorie goal of 1,200 to 2,000 kcal based on starting body weight, a fat gram goal of 25 per cent of total calories, and do 175 minutes of weekly moderate to intense exercise.
Results suggested app users recorded fewer items, fewer calories, and less fat as time progressed in the study and on the weekends.
In particular there was a weekend effect, with participants recording less food eaten between Thursday and Sunday than weekdays.
However, the study found that more food was recorded in January which suggested users were worried about Christmas weight gain but not in other months.
Prof Pellegrini said: "Adults generally gain weight during the holidays and self-monitoring can help to manage weight during this period.
"Weight loss is a common New Year's resolution and may explain the increased number of foods reported in January; however, the typical pattern of self-monitoring during the holidays is not well established."
To improve the app, text messages providing feedback, reminders, and encouragement could people stick to the diet, he added.
The study was published in the Journal of Nutrition Education and Behaviour.