[pmsaue0]

Cool idea and neat sliders and calculation execution! I agree with most others who say that it's not clear in the first 2 seconds what to do. Perhaps in the header:

h1: weight loss calculator h2: easily plan your diet and exercise routine

I would recommend a numbered-list / stepwise approach for user input (all on the same page still), instead of the all-at-once approach (which is convenient if you know how to use it, but confusing otherwise)

Perhaps have a time indicator that says something like, "it will take 2 months for you to lose 20 lbs at this rate"