Misaligned sweetness and calories deceive our body's metabolism into gaining weight.
Dana Small, the senior author and Professor of Psychiatry at Yale University School of Medicine, said: "A calorie is not a calorie".
Responding to the study, published in the journal Current Biology, Tam Fry, of the National Obesity Forum, said: "This research should be enough to convince you that artificial ingredients, whether they be in food or drink, can screw up your system even though they may sound healthy".
However, a new research study indicates that these benefits may just be theoretical since artificial sweeteners may actually increase the risk of diabetes and weight gain.
If there is a mismatch between the actual calories and perceived sweetness, the brain could become confused and metabolize less, which could increase the risk for diabetes and other metabolic diseases.
The results were discovered by giving 15 people drinks with varying calorie contents, then measuring their brain response in an MRI scanner. After that it was seen that the energy burned was different.
"The assumption that more calories trigger greater metabolic and brain response is wrong". This might lead to the consumption of more food.
They found when there was a "mismatch" between sweetness and calories - as is often the case with diet drinks or foods because they are not as sugary - the calories fail to trigger the body's metabolism. Finally, the reward circuits will also fail to get the calories and to take them.
British experts, who are more skeptical about the findings, are of the opinion that those who are concerned about taking diet drinks should stick to drinking water. The earlier studies will explain the association which is present in between the artificial sweeteners and diabetes.
"The statement that a calorie is not a calorie is gobbledegook", said Tom Sanders, Professor emeritus of Nutrition and Dietetics, at King's College London.
He also stated that an analysis of experiments in which sugar sweetened drinks were replaced by artificially flavored drinks showed some weight loss.
Some diet foods and artificial sweeteners will cause the weight gain and increase the diabetes level.