High-carb diets may put dieters in better moods

The high-protein versus high-carb diet debate continues with the release of a new study that looked at something usually left out of the weight loss equation: mood.

Most studies on these two popular weight loss methods -- and on diets in general -- typically focus on pounds lost, pounds kept off and cardio-vascular function. But in a study published today in the Archives of Internal Medicine, Australian researchers took a more holistic approach. In addition to weight they also measured mood, discovering that those who stayed on a high-carbohydrate, low-fat diet for a year had better moods than those who were on a low-carbohydrate, high-fat diet, although the two groups lost about the same amount of weight.

The researchers randomly assigned 106 overweight and obese men and women to either a low-carb, high-fat diet or a high-carb, low-fat diet for a year. The groups were somewhat restricted in their calorie intake -- women were allowed 1,400 calories, and men about 1,700. On the low-carb plan, diets consisted of 4% carbohydrates, 35% protein and 61% fat, while the high-carb was composed of 46% carbohydrates, 24% protein and 30% fat.

The participants' weight was noted at weeks eight, 24, 40, and 52, and their mood was evaluated via three questionnaires that measured various aspects of mood, including tension-anxiety, depression-dejction and anger-hostility.

Both groups lost a significant amount of weight -- about 30 pounds. In the early weeks of the study both groups showed an improvement in mood. However, over time that changed. Mood improvements remained in the high-carb group but went back to original levels for the low-carb group.

Researchers speculate that the results could be evidence that it's tough sticking with a low-carb diet over a longer period of time, especially in cultures that favor carbohydrates. "Over the long term, trying to maintain that dietary pattern may mean coming across a lot of challenges," said Grant Brinkworth, lead author of the study and a research scientist at the Commonwealth Scientific and Industrial Research Organisation -- Food and Nutritional Sciences in Adelaide. "That may cause cause a negative mood impact, even though you’re getting a good weight loss." That bad mood might eventually affect adherence to the diet down the road as well, he added.

Another theory is that in a low-carb diet, lower levels of serotinin may be produced. Serotonin is a neurotransmitter responsible for lending a feeling of happiness and well-being, and eating carbs can increase its release.

-- Jeannine Stein

Photo credit: Krista Simmons / Los Angeles Times