A lot of the “diet” soft drinks and products now have few or no calories but still have sweetness due to added sweeteners. It has been thought therefore they should not contribute to being overweight. And here is where the oversimplified “calorie -in vs calorie out” idea fails.
Growing evidence suggests that these sweeteners have effects on our brains urges for food and the gut bacteria. The human brain responds to sweetness with signals to eat more. By providing a sweet taste without any calories, however, artificial sweeteners cause us to crave more sweet foods and drinks which can add up to excess calories.
There is also increasing evidence that artificial sweeteners may alter the bacteria in our gut and stimulate weight gain or prevent weight loss.
Though it is still early days to be proving the exact mechanism multiple studies have shown not only that artificial sweeteners do not help with weight loss, but that they may increase the risk of being overweight and getting type 2 diabetes.
For example – one study of 3,682 individuals examined the long-term relationship between consuming artificially sweetened drinks and weight. The participants were followed for 7-8 years and their weights were monitored. After adjusting for common factors that contribute to weight gain such as dieting, exercising change, or diabetes status, the study showed that those who drank artificially sweetened drinks had a 47% higher increase in BMI than those who did not.