But using a smartphone app can help you stick to your regime by offering guidance, tips, support from other users and a clear map of your progress.
Here are five of the best diet and fitness apps for Android and iPhone to help you stay in the zone...
Calorie-counting can be tricky when you're out and about. Luckily calorie-tracking app, MyFitnessPal, has the calorie content of over 2 million foods and you can search the calorie database using your camera to scan barcodes.
It also had loads of fitness features, hundreds of exercises and even lets you customise your workout routine.
This Google app doesn't count calories or monitor your food, but it does make exercising more fun by recording your running or cycling routes.
It also plots your course on Google Maps, reports statistics like maximum altitude and makes it easy to share your fitness progress with friends.
Enter your current and target weight and this fun food-tracking app will help monitor your daily calorie intake and tell you how far off you are from reaching your goal.
You can 'scan' in packaged foods to discover their health benefits and generate healthy meal ideas by telling the app what you've got in the fridge.
It also comes with social options for getting support from friends and other users but its core functions can be used offline as well.
Weight training is often neglected when exercising, particularly by women who may see it as a male-dominated activity.
However building muscle is actually one of the best things you can do to lose weight. Increased muscle mass means more calories burnt.
The app is packed full of great weight-training exercises and makes it easy for beginners to get started right away with loads of routines, or you can create your own.
Your very own diet assistant - this handy app has hundreds of different diet recipes. It also send your reminders at meal-times and lets you create grocery lists.
Author Bio: Matt Powell has uncovered all these fab apps on behalf of Broadband Genie, where you can find the best iPhone deals and the latest smartphone news.
TOP 10 HEALTH AND FITNESS APPS
Do you use diet apps? Tweet us @handbagcom.
TOP 4 EXERCISE MYTHS BUSTED
FORGET THE GYM! 5 AT-HOME WORKOUT ACCESSORIES
ARE WOMEN IGNORING CERVICAL CANCER SYMPTOMS?