Hi Vikas,
Thanks for getting in touch with us and sorry for the inconvenience.
It sounds like the issue you may be having relates to API call
throttling limits that are in place to prevent abuse of the API.
These are modified for FatSecret Platform API Premier users and if
you'd like further information please contact us here:
http://platform.fatsecret.com/api/Default.aspx?screen=cu&id=3
All the best,
Len