Can your diet make you happy? Australian researchers showed that the type ofweight loss diet you choose might affect your mood. The researchers took over 100 people and randomly put them either on a very low carb/high fat diet or on a high carb/lower fat diet for a year. Here's the nutritional breakdown of the two diets:

Low Carb/High Fat Diet

  • 4% carbohydrate
  • 35% protein
  • 61% fat

 High Carb/Low Fat Diet

  • 46% carbohydrate
  • 24% protein
  • 30% fat

The women's diets averaged around 1400 total calories while the men's averaged about 1700. The researchers measured the participants' mood, emotional well-being, and thinking function before and after the year-long diets. The low carb diet was very restrictive on carbohydrates with an amount equal to no more than one apple and half a slice of bread. The "high carb/low fat" diet was not as extreme and was only moderately high in carbs and moderately low in fat.  Here's what the researchers found:

  • Weight Loss. The people on both diets lost an impressive amount of weight - about 30 pounds on average in a year.
  • Mood Changes. Both groups experienced positive changes in their mood during the first 8 weeks of the diets. But only the high carb/low fat dieters were still scoring positively on the mood scales after a year on the diets. The mood boost didn't last for the low carb/high fat dieters.
  • Thinking Function. Neither group changed much when it came to thinking ability over the year long diet.

So why did the higher carb dieters fare better mood-wise than the low carb dieters? While this study does not answer that question, the researchers have some guesses. This initial boost in mood in both groups may have been from feeling good about losing weight. But being on a low carb diet for a long time is hard. Turning down the bun on your burger or passing up the baked potato can be a drag. The low carb dieters couldn't even eat much fruit on such a low carb allowance. Another possible explanation for the mood lift in the high carb group is that their serotonin levels may have been higher. Serotonin is a brain chemical that may improve mood and lower anxiety. Carbohydrates seem to produce more serotonin while fat and protein seem to decrease it.

How to High Carb. If you want to eat a healthy high carb diet, aim for about half of your calories from carbohydrates. But choose your carbs wisely. Try to make as many of your carbs healthy carbs. That boils down to whole grains and high fiber starchy vegetables.

  • Whole wheat breads and cereals
  • Brown rice
  • Baked or roasted potatoes with the skin
  • Starchy beans and peas

It fine to eat some sugar and refined carbs like white bread and pasta. But try to get whole grains for at least three of your daily grain servings. And be sure to go easy on the sugar. But remember, for weight loss, it's total calories that really count. So as long as you keep your sugar calories in check, you should be able to get to a healthy weight. 

Beth Kitchin MS RD
Assistant Professor
UAB Department of Nutrition Sciences