Versions of the Atkins Diet are among the most popular diets for westerners trying to reduce weight. An eating regime that is very low in carbohydrate, high in protein, high in fat, it is very effective in dropping weight, and many people make it their permanent eating style.
However, a study from Australia, comparing this "ketogenic" diet (mimicking starvation by forcing the body to burn fats rather than carbohydrates) with the standard high-carbohydrate, low-fat, energy-restricted diet for obesity treatment, showed an unexpected downside.
Dieters who stayed on the low-carb diet for more than a year had low moods compared to the high carb dieters, whose mood improved.
Comparing High Carb, Low Fat Diet with Low Carb, High Fat
The Australian researcher who developed the study, Dr. Grant Brinkworth, of CSIRO Food and Nutritional Sciences, randomly assigned 106 overweight and obese participants around the age of 50 to maintain either a very–low-carbohydrate, high-fat diet or a high-carbohydrate, low-fat diet for one year.
The diets were structured to ensure all dieters ate the same daily amounts of calories (1433 calories for women and 1672 for men). The dieters were given counselling sessions with nutritionists to help them understand their diets and how to prepare their meals.
Participants on the low carb diet were prescribed a dietary plan aimed at providing only four percent of their total energy as carbohydrate, 35 percent as protein, and 61 percent as fat.
Those on the low fat diet were prescribed 46 per cent of their total energy as carbohydrate, 24 per cent as protein, and 30 per cent as total fat.
At intervals over the trial, changes in participants’ body weight, mood and well-being, and cognitive functioning (thinking, learning and memory skills) were assessed.
Atkins Diet Effective in Dropping Pounds and Mood
At the end of the 12 month trial, both groups of obese people had lost a similar amount of weight – an average of 13.7 kilograms (about 30.2 pounds) per person.
However, Dr. Brinkman said there was a noticeable difference between the two groups – the low fat dieters had improved mood scores at the end of the year, while the low carbs dieters’ mood had returned the low levels they had started the diet with.
Initially, after the first eight weeks all participants experienced an improvement in mood. “It’s natural to feel better when you can see that sticking to a diet is producing results,” he said. But for the low carb dieters, this up mood didn’t last.
“Over the course of year, there were significant diet interactions for Spielberger State Anxiety Inventory, Beck Depression Inventory, and Profile of Mood States scores for total mood disturbance, anger-hostility, confusion-bewilderment, and depression-dejection, with greater improvements in these psychological mood states for the low fat participants, while the mood of low carb participants returned toward more negative baseline levels.”
There were no noticeable differences in participants’ thinking, learning and memory skills on either diet.
Why The Atkins Diet Might Depress Mood
“This outcome suggests that some aspects of the low-carbohydrate diet may have had detrimental effects on mood that, over the term of one year, negated any positive effects of weight loss,” he said.
While he didn’t have an exact answer why, he hypothesised there could be three main reasons:
- the social difficulty of adhering to a low-carbohydrate plan, which is so different from the typical Western diet full of pasta and bread;
- the prescribed, structured nature of the diet, requiring measuring and thought instead of just relaxing and enjoying eating;
- the effects of protein and fat intake on brain levels of serotonin, a neurotransmitter related to psychological functioning.
Dr. Brinkman said that shorter stints of a low carb diet had positive effects in reducing weight, providing improved health to people with cardiovascular problems. However, too little is known about the long-term effects of sticking to a low carbohydrate diet.
“While recent clinical studies have shown that low-carbohydrate diets can be an effective alternative dietary approach for weight loss, their long-term function, including mood and cognition, have been poorly studied.”
Dr. Brinkman’s study, ‘Long-term Effects of a Very Low-Carbohydrate Diet and a Low-Fat Diet on Mood and Cognitive Function’ was published in the November 9,2009 issue of Archives of Internal Medicine.
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Sue Cartledge - I'm a science, health, nutrition and lifestyle journalist, fascinated by the way the physical world operates in all its forms, and how ...
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