What is "whatsapp", & can you explain that "fitness pal" please? What does it tell you, how does it help? Does it tell us our calorie intake &/or how much energy we burn?
I'm not asking for myself.
If you had it it would just nag you to stop eating iced buns and smoking.
I was not asking for myself.

Seriously, what IS whatsapp? How does the Fitness Pal work, what does it tell us?
My fitness pal is a calorie counter with knobs on. You tell it what you weigh now, what you want to weigh, how fast you want to lose the weight and a few other details and it tells you how many calories you need to eat per day to achieve your goal.
Then, when you eat you tell it what you've had, It knows all the branded stuff, it scans bar codes, and it knows what's in unbranded stuff if you tell it the weight. Every time you enter a new food it stores it in it's library so that the next time you have it you just have to tap 'cod loins' and you're good to go.
It gives you progress reports and reminds you to update it if you forget.
If you do any exercise it adds the calories you've 'earned' to that day's allowance.
It's actually fun. It's interesting and very motivating.