I have browsed on the Blackberry app store and the Google play store and have come across a variety of different apps for weight loss and muscle gain. In the last few weeks I have downloaded and had a look at 8 different apps. Some were for weight loss and some were for muscle building. In all honesty, they are a bit of a let down, and here's why.
The apps that I downloaded were pretty basic - including a BMI calculator, a basic calorie counter and some exercise diagrams. Granted, I did only download the free ones, but about half of them were completely free, with the others having an option to upgrade to the full version at a cost, so I haven't looked at a few of the full versions. With that being said, they still seem pretty basic. I have seen some reviews of fitness apps that say they are better than personal trainers.... I'm not sure whether those people were drunk or not, but I have no idea how an app can be better than a trainer. Yes, you can enter your details, record your food intake, type in the exercises you have done, but do you really need an app for that? A big part of a personal trainers job is to motivate you, tell you/show you what to do and how to do it, be supportive and connect with you, yes you guessed it, on a personal level! An app cannot motivate you, show you how to do exercises, correct you if your form isn't up to scratch etc etc.
To me, it just seems like the apps are a technological version of writing things on a sheet of paper with a pen. Some people may think the app is more convenient, but going into the gym with your mobile phone or tablet isn't the way to go forward, you're there to train, not have your techno gadgets out! If you're unsure on your technique, ask a trainer/instructor working in the gym, as the app may have a picture, but you're still guessing how to do it, whereas a trainer can easily correct you. Hiring a personal trainer costs money, but an app is just pointless if you ask me. I downloaded a few and just couldn't see a benefit of keeping them. The only app that I can think of that would be good if you were into distance training, would be one that tracks where you run/cycle, how far, your heart beat, speed etc. That would be handy information if you wanted to keep track of your progress in more detail. The muscle gain apps had charts to fill in with how much you lifted, reps, sets etc, but the problem with apps is they can fail, crash, or even get removed from the app store, pen and paper can't be removed!
Sorry for the negative post, and some may disagree with me (and that's fine) but they just seem to be a little gimic to me.