Eating a diet high in carbohydrates and low on fat helps people lose weight and also makes them feel happier than a diet with less carbs but more meat and dairy, Australian researchers say.
The study was based on 106 overweight or obese people in Australia aged 24 to 64 who followed one of two diets for a year: a low-fat, high-carb diet with bread, pasta and rice, or a low-carb, high-fat diet with more meat and dairy.
Researchers from several Australian institutions including CSIRO, the University of South Australia and Flinders University found the dieters lost an average of 13.7 kg (30 lbs) each, with no significant difference in weight loss between the two groups. But the dieters following the high-carb, low-fat diet were found to be less angry, hostile, depressed and confused than those eating more meat and diary products after the year.
"Over one year, there was a favourable effect of an energy-restricted (low-fat) diet compared with an isocaloric (low-carb) diet on mood state in overweight and obese individuals," the researchers said in their report published in the journal Archives of Internal Medicine. The researchers said both groups were less angry, less depressed and less confused after eight weeks of dieting but over the course of a year, those on the low-fat diet maintained their improved mood, while those on the low-carb diet returned to previous moods.
The researchers said both diets followed for 12 months had a similar effect on working memory, which improved over the year but the speed of mental processing remained largely unchanged. They said the results of their study were consistent with results from epidemiological studies showing that diets high in carbohydrate and low in fat and protein are associated with lower levels of anxiety and depression and have beneficial effects on psychological well-being.