Artificially sweeteners are typically between 200 and 2000 times sweeter than sugar (sucrose).
Aspartame is 200 times sweeter
Acesulfame-K is 300 times sweeter
Alitame is 2000 times sweeter than sugar.
Fact is that sugar is not the primary concern when considering causes of obesity.
• Thus replacing sugar with artificial sweeteners does not dramatically affect weight control compared with a reduction in fat intake.
Appropriate use of artificial sweeteners may help control energy intake and bodyweight in the short-term, but little is known about the long-term impact of artificial sweetener consumption on energy intake and body weight
• Thus, current evidence suggests that, although artificial sweeteners may be helpful in the short-term, there is little long-term benefit of in people of normal, body weight.
It is suggested by some that consumption of artificial sweeteners or low-energy foods tends to be followed by an increase in energy intake to make up for the lost energy in people of a normal bodyweight.
A lower intake of energy relative to energy expenditure promotes weight loss.
However, the science is not as straight forward as it may seem. The body is capable of sensing and adapting to a reduced energy intake, and as a result people may compensate for this by eating more later.
People who exercise dietary restraint (i.e. watch what they eat carefully) may benefit from artificial sweeteners as they tend not to compensate for energy intake.