Load cell weight lossing rate or flow rate

How to i gate the weight losing rate by using Hx711

Any time you use the word "rate" in a sentence, you ALWAYS relate it to TIME. So what time frame are looking at? loss per second, loss per minute, loss per day?
In all cases, you need to measure the weight once at the beginning of the time period and again at the end of the time period. The difference in weight is the loss per your unit of time.
Paul

Per minute

But the value will update in .5 sec

Well, then you can add up the change that happens every 0.5 seconds and once a minute, divide that total by 120.
Paul

I know buy i need the code to dentyfy the mass flow rate

*but

Start working on it.
Paul