Overweight and obese women who habitually drank diet beverages lost more weight if they substituted water for the diet beverage. Over the course of 24 weeks on a reduced calorie diet, the water drinkers lost an extra 1.2 kg (2.6 lb) compared to those who continued their diet beverage habit.
Furthermore, the researchers found that the water drinkers had healthier values on insulin levels, HOMA-IR (a measure of insulin resistance), and after-meal blood sugar levels.
It was a small study with only about 30 in each experimental group. Whether similar results would be seen in men is unknown to me.
In the past, I’ve advised dieters it’s OK to drink diet drinks in moderation while trying to weight. I may have to revise my recommendations. On the other hand, if diet drinks help keep you happy and on a successful weight-loss journey, they may be helpful. The diet beverage consumers still lost 7.6 kg (16.7 lb) compared with 8.8 kg (19.4 lb) in the abstainers. But diets don’t work, right?
PS: I haven’t read the full text of the article; just the abstract.
PPS: Steven Novella at Science-Based Medicine blog concludes that low energy sweeteners probably help with weight control.
Diabetic Mediterranean Diet 