How does nicotine affect heart rate and weight loss?
Lucy contains nicotine (of course), and nicotine is known to acutely raise heart rate. However, heart rate will typically return to baseline after the effect of nicotine have worn off.
As far as weight loss, there has been quite a bit of research on the effects of nicotine on weight loss (for example here).
Bear in mind, Lucy has not undergone any studies as a weight loss aid and is not FDA approved for this use.