PERHAPS it?s too early to bring this up, what with holidays approaching and, of course, all the food that comes with the celebrations. But then again, the information might be useful for those looking ahead to January resolutions and considering how to achieve their goals.

Australian researchers have found that a year after starting a diet, people who opted for the low fat road have better moods than those on a low carbohydrate plan.

The team led by Grant Brinkworth of Commonwealth Scientific and Industrial Research Organisation (CSIRO)-Food and Nutritional Sciences, Adelaide, Australia worked with a group of nearly 120 people classified as either overweight or obese and with an average age of 50 for the study.

Each participant was randomly assigned to either: a low carbohydrate diet made up of 4 percent carbohydrates, 35 percent protein and 61 percent fat (no more than 20 percent saturated fat); or a low fat diet that was made up of 46 percent carbohydrate, 24 percent protein and 30 percent fat (no more than 8 percent saturated fat).

Over the course of a year, participants made regular visits to the researchers, who checked that the diets were being adhered to and to gauge how the participants were faring not just physically but emotionally through a series of surveys that gauged their moods and mentally via computer exercises that tested memory and the speed at which their thought processes worked.

At the end of the year, Brinkworth and his colleagues found that the participants in each group lost an average of 30 lb. What was surprising to them, however, was ?that despite similar weight loss,? the team wrote in their study, ?over the long term many of the benefits regressed in the low carbohydrate diet group such that participants in the low fat diet achieved better outcomes.?

Participants? mood

In case you?re wondering, the term ?better? refers not to the weight loss capacity of either diet, but rather to the participants? moods. During the first two months of the experiment, the researchers noted that the mood and memory data were similar for both groups. But at the end of a year, the researchers found that the low carbohydrate group?s mood had declined while the mood of low fat diet group remained stable.

?Thus outcome suggests that some aspects of the [low carbohydrate] diet may have had detrimental effects on mood, that, over the term of one year, negated any positive effects of weight loss,? the researchers wrote.

The team proposed a few theories to explain the change in mood. One idea is based on the typical composition of a meal, which often involves significant portions of carbohydrates in the form of bread, pasta or rice. The researchers suggested that since study participants in the low carbohydrate group couldn?t have as much of these ingredients as they were used to, they may have felt challenged by the long-term change to their eating habits, especially if they were in social gatherings such as at parties or dining out with friends.

Keep in mind that the team?s findings and theories all need to be investigated further, so those planning to change their eating habits for whatever reason in the coming year shouldn?t rule out particular diets based on this one study alone. In the first place, only two diets were studied here. And second, mood shifts in early 2010 after the newness of Christmas presents wears off and long days at school or in the office might be attributable to the realization that Christmas celebrations and all the fun associated in these activities are, once again, several months away.

The study was published online Nov. 9 in the journal Archives of Internal Medicine.

E-mail the author at massie@massie.com.