11/27/2009 - Articles

Low-fat diet better for your mood

By: Susan Aldridge, medical journalist, PhD


A low-fat diet is the traditional approach to weight loss. The reason is simple – fat is high in calories, so low-fat is low-calorie. However, there are alternatives to the low-fat way. There has been a lot of interest in recent years in the low-carb diet, which tends to be high in protein and fat. Research has shown that both approaches can led to significant weight loss.

What we don’t know is how low-fat and low-carb diets affect your mood. This is an important aspect, because if you feel low or irritable on a diet, you won’t stick with it and won’t lose the weight or keep it off. Psychology is the key to any weight loss plan, whether it is a low-fat diet or some other way.

Researchers at the Commonwealth Scientific and Industrial Research Organisation, Food and Nutritional Sciences, Adelaide, Australia, studied a group of 106 overweight and obese participants of average age 50. Fifty five of them were assigned to a low-carb diet and 51 to a low-fat diet for one year. Changes in body weight, mood and well-being and in cognitive functioning (thinking, learning and memory) were monitored during the study period and at the end.

After a year,  average weight loss was 13.7 kilograms (30.2 pounds) in both groups. Both groups experienced an improvement in mood after about eight weeks – probably linked to the euphoria of beginning to shift some weight. But the lift was only sustained in the low-fat diet group while those in the low-carb diet group returned to their original mood state. The researchers believe it’s concerning that the negative impact of the low-carb diet may offset the benefits of losing weight. The reason why low-carb does not boost your mood might because it is hard to follow in Western society where eating tends to be dominated by starchy foods like bread and pasta. Or the high protein and fat intake of the low-carb diet might lower levels of serotonin, the ‘feel good’ chemical, in the brain. The researchers add that neither the low-fat diet or low-carb diet had any particular impact on cognitive functioning.


Grant D et al Long-term effects of a very low-carbohydrate diet and a low-fat diet on mood and cognitive function Archives of Internal Medicine November 9 2009;169:1873-1880


Created on: 11/27/2009
Reviewed on: 11/27/2009

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