Nov. 9, 2009 -- If you're looking to lose extra pounds and weighing the
options of a low-fat diet vs. a low-carbohydrate diet, you might want to
consider the moody findings of a new diet study.
The study, published in the Archives of Internal Medicine, shows a
short-term improvement in the moods of people who went on low-fat and low-carb
But those mood gains didn't last in the long run for people on low-carb
The study included 106 overweight and obese adults
(average age: 50) in Adelaide, Australia. They were randomly split into two
groups. One group was assigned to go on a low-fat diet for a year. The other
group was assigned to go on a low-carbohydrate diet for a year.
Here's a quick look at those two diets:
Low-fat diet: 46% of calories from carbohydrates, 24% of calories from protein, and 30% of calories from fat (less than 8%
from saturated fat).
Low-carb diet: 4% of calories from carbohydrates, 35% of calories from
protein, and 61% of calories from fat.
People in both groups got the same daily calorie budget. They also met
regularly with a dietitian and completed mood surveys several times during the
By the end of that year, people in both groups had lost the same amount of
weight -- about 30 pounds.
At first, mood improved for people in both groups. That was no surprise; the
researchers had expected to see that bounce in mood as people started to shed
But better moods didn't last for people on the low-carb diet. By year's end,
their mood was right back where it had been before dieting and losing weight.
However, the mood improvements lasted for people on the low-fat diet.
It's not clear why the mood benefits faded for people in the low-carb
But the researchers suggest that the low-carbohydrate diet may have been too
hard and too different from how people used to eat.
The low-carb diet may have been "so far removed" from normal eating patterns
that it became a lot of work and a social burden, note the researchers, who
included Grant Brinkworth, PhD, of the Commonwealth Scientific and Industrial
Research Organization in Adelaide, Australia.
"Although, in the short term, participants may have been able to meet the
challenges presented by this dietary pattern, over the longer term, it may have
increased participant isolation, leading to the negative impact on mood state
that may provide a possible explanation for the effects that were observed,"
Brinkworth and colleagues write.