From Calorie Control Council: https://caloriecontrol.org/the-state-of-the-science-on-stevia/
When substituted for sugar, stevia can help with weight management by reducing added sugar and calories. Stevia can be used by anyone, including normal-weight persons, who simply want to reduce overall sugar intake and improve dietary quality. All major regulatory bodies found stevia to be safe and suitable for the entire family.
One Caveat: Stevia, like all LNCS, is a tool for managing weight and dietary quality, but should not be the only tool. Placing the burden of solving the obesity crisis on a single factor would be inappropriate. This requires a gradual change in eating style, lifestyle, with stevia and LNCS as part of that plan.
Foods containing stevia may help with a long-term modest effect on body weight, body mass index (BMI) and waist circumference.
Foods containing stevia help lower total calorie intake, without over-consumption later in the day.
Stevia has been confirmed as safe and appropriate for persons with diabetes. As a sugar replacer, stevia may benefit blood glucose & insulin levels, with no negative effect on glucose homeostasis.
Long-term, the use of stevioside may have a small lowering effect on blood pressure, though most studies used consumption levels higher than the acceptable daily intake (ADI).