Slimming world calories

How old, tall and heavy is she? Maybe she is so overweight that she's losing on 2100kcal. Or she's not logging correctly.

She's burning more than 2100 calories

The thing with programs like Slimming World, Weight Watchers, etc, is that they work the same way as any other successful program - by creating a calorie deficit. The thing with just using MFP is that you are totally in control and fully aware of what that calorie deficit is - you can create it with any combination of foods that you find nutritious, satiating, and enjoyable.

Programs like SW and WW don’t teach an individual how to build a long term healthy, calorie appropriate diet. They work because they have pre set options which some people like, but it in turn makes a person dependent on that program for the long term in order to stay successful. It’s like never learning how to ride a bike without training wheels, in my opinion. I would rather learn how to count calories and build a healthy diet for myself that will see me through weight loss and subsequent maintenance and in my opinion, that’s what MFP offers, and it’s free.

As to your friend - it’s really pointless to compare. Time and again we have posts like this where someone is sure that someone else is losing weight eating more cals than they should be able to and the answer is always - they are eating at a calorie level appropriate for THEIR situation and goals and you should do the same.

I gained on slimming world.....
Because as a volume eater I can pack away a whole lot of Thier "free" foods. They told me it was because I didn't eat enough

Now that I'm weighing my food I can see where I was going wrong and trust me I wasn't undereating