16/01/2014 08:21 GMT | Updated 17/03/2014 05:59 GMT

Fitness Apps Have Risks

Since New Year magazines poured into our shops and onto our mobile devices they've all seemed keen to tell us about one thing: fitness apps to help you with that 'New Years resolution'.

In many ways it is great to see apps out there that make it easier for us to track our calories and the amount of exercise that we do, to help us balance the food books, but at the same time those apps can be really harmful.

Many online sites and printed media have mentioned one app specifically, My Fitness Pal. As a user of the app for almost a year now, I know it has many good sides. You tell it whether you'd like to lose, gain or remain at the same weight and how much you'd like the number to change a week (the most you can aim for is 2lbs weekly).

From that it tells you it recommends you eating 1500 calories, which is great. Then you tell it you've walked for an hour and it does all the maths.

But here's the harmful thing, not just with this app but with some others on the market too. You can completely alter the amount of calories you want to aim for. You can go as low (or high) as you want to.

After observing people on twitter that use this app, I became increasingly aware that many users were in fact under 18 (the age you have to say you are) and using it to seriously restrict and control their intake of calories. Many of them openly admitted to being anorexic and would share pictures of not only themselves but screenshots of the app saying they'd only eaten 100 calories all day.

It's certainly a worrying trend. There's also no limit as to the weight you can set, even though you inform it of your height. If you're 6ft and want to be five stone it doesn't physically stop you from inputting that value.

There's nothing wrong with people using apps to help them with their weight and to make them feel confident, but not stopping people from being so highly irresponsible is a huge concern. Because of this I tend to use My Fitness Pal combined with Noom, another app that gives you the breakdown of what you're eating into 'good' 'okay' and 'bad' and also can have a pedometer to track your walking for you.

Noom is clearly a lot more about ensuring you are not just meeting any aims you have but that you are also aware of what you are (or aren't) putting in your body. But I expect that it has its floors too, and that I just haven't picked up on them yet.

The reality is some of these apps are dangerous and are encouraging very bad approaches to weight, appearance and general health. It's perfectly okay with wanting to set your calories at your own level and in fact your weight, but the app should at least consider sharing the risks or information with users about what they are doing - such as becoming underweight, undernourished and not getting enough nutrients to be healthy.

So when you're choosing which fitness app to go for in the New Year, have a look around and consider what is right for you and how vulnerable you might be to knocking down that recommended intake number.