A study published in the journal Appetite has found that consuming sugary drinks in moderate quantities does not promote weight gain, carbohydrate craving or adverse mood effects in overweight women when they do not know what they are drinking.

Study participants were given either soft drinks containing either sucrose or aspartame and were told to continue with their normal diet and exercise habits. In total, they drank one drink, four times per day, for four weeks.

The results showed that the subjects did not suffer adverse effects, such as weight gain or mood fluctuation, if they do not know whether or not they are drinking a sugary or artificially-sweetened drink. Instead women took in fewer calories elsewhere in the diet, to balance the calories in the drinks.

Researchers say the primary causes of any negative effects of sugar on food choices and mood may be psychological.

"Widespread publicity about the supposed harmful effects of sugar may make such effects more likely, as believing sugar to be harmful may encourage negative emotions after eating sugary food and lead to the abstinence violation effect," said researcher Marie Reid. "In other words, knowing that you’re drinking sugary drinks, while believing that they’re harmful, might result in the derailing of a generally healthy low-fat diet."