The debate over cutting fat or carbohydrate calories for successful weight loss and weight loss maintenance continues. While some people say an eating plan filled with low-fat fruits, vegetables, and whole grains is best for people trying to lose weight, others argue that eliminating excess carbs (breads, added sugars, and even fruits and dairy) is key. Well, a new study published in the Archives of Internal Medicine adds another twist by identifying a certain diet with improved mood in the short and long term.1  

Researchers randomly assigned about 50 overweight/obese adults to a calorie-restricted very-low-carbohydrate, high-fat diet and another 50 or so overweight/obese adults to a calorie-restricted high-carbohydrate, low-fat diet for one year. Changes in body weight, mood and well-being, and cognitive functioning (thinking, learning, and memory skills) were measured throughout the study. After one year weight loss was the same in both groups (about 30 pounds), but improved mood which was originally found in both groups lasted to one year only in people following the low-fat diet. The researchers suggest that some aspects of low-carbohydrate diets may have detrimental effects on mood over time like: the social difficulty of adhering to a low-carbohydrate plan, which is counter to the typical Western diet full of pasta and bread; the prescribed, structured nature of the diet; or effects of protein and fat intake on brain levels of serotonin, a neurotransmitter related to psychological functioning.

As we've mentioned before on this blog, the real indicator of success of any "diet" is whether it can be maintained for a lifetime. Short-term changes to eating habits may lead to weight loss, but the weight will be regained if the eating habits aren't part of your new lifestyle. When you cut calories pay attention to your mood and how the foods you eat affect your mood. Do you find that an eating plan with more low-fat (vs. low carbohydrate) foods is easier to stick to? Do moderate amounts of breads, fruits, vegetables, and low-fat dairy products keep your mood at an even keel? If so, a low-fat eating plan is probably best for you because these are all things that will influence your long-term success with calorie control.

1Brinkworth, GD. (2009). Long-term effects of a very low-carbohydrate diet and a low-fat diet on mood and cognitive function. Arch Intern Med, 169(20), 1873-1880.