Brief answer...given below
Thanks for the query.
ACE pill has mainly caffeine,green tea extract,VIT B 6 etc in it.
Available data doesn't suggest the existence of any interaction of ACE with CITALOPRAM
,however caffeine in ACE can cause irritability,restlessness
If you are a heart patient or having high blood pressure
,then it can cause problem.
In addition caffeine may interact with hormones preparations containing estrogen and progesterone
If there is none of the above mentioned issues you may take diet pill,however It is better to talk to your treating doctor and take the diet pill only if he allows you.
In the end,I would want to add one thing that no amount of diet pills work if person doesn't control his calories and if he doesn't exercise.
I hope it helps,however you may revert to me for any further query.
Best of luck