You aren't going to be healthy if you lose weight too quickly. Weight loss should also not generally be a goal. Being more active, lowering blood pressure or cholesterol, doing that long hike you've always wanted, those are attainable goals that will improve your quality of life. If you can afford it, consult with a doctor or qualified trainer about the best way to achieve these goals for your body type and health conditions.
i think it would be best to vist a doctor before starting anything too serious.
seeing a doctor is great, they'll get bloodwork done, check blood pressure and anything else they do hahaha
doctors will tell you what weight range js healthy for you, and advise you on how to lose weight properly!
Download myfitnesspal. Start reading health blogs. Google is your friend, do some research into many different phrases... Try things like 'beginner Weight loss' or 'weight loss for the obese' or 'beginner walking program'... there are a ton of blogs out there with lots of info for almost every life situation. You need basic tips and structure and you can find it with minimal effort.
I really agree with the people here who have recommended talking to a doctor or health professional before doing anything major. Particularly because you are fourteen, your body may have different nutritional and activity needs than an adult's, and your metabolism won't react the same way as a thirty-five year old's (like mine. :D ). Google and health blogs can give you great starting points, but most of the info you find will be aimed at adults who have finished growing (except side-wise ;) ). You would really be well served to have a personalized or at least youth-oriented plan that will work for your life and your body. If you're comfortable talking to him/her, your school health teacher or nurse might be able to help you get started too.
I know you said you want to lose weight fast, and I totally get that. As someone who went through high school heavy, I REALLY get it. But believe me, losing it too fast or in a way that doesn't give your body what it needs can cause a load of problems, especially when you're still growing. If you can be patient with yourself, you can look good and feel good.
Some general rules of thumb to get you started:
Don't put off getting more active. That doesn't mean start running right out of the gate; but there are little things you can start even before you lose any weight: taking a walk every evening; doing gentle strengthening exercises; etc. Choose exercises that challenge you, but that you can be successful with. (This can take some searching, as I'm discovering right now. Try lots of different things!)
As much as possible, choose exercise that is FUN. Try different things until you find something that you will be able to enjoy doing! That will make it a lot easier to keep going and stay motivated. I'm starting a dance-based fitness class this fall that sounds like a blast. If you have access to them, Video games that get you moving like Just Dance, DDR, or some of the Wii and Kinect games can be loads of fun, and can be done at home.
Another thing that can help with the exercise thing is finding programs that are "fat friendly" - that make you feel like you can love your body and succeed, and that provide the necessary adaptations for the body shape and realistic capabilities of bigger people. I don't have a reference, but I remember reading somewhere that research has shown that watching videos of thin, beautiful people work out can actually encourage weight gain because of what it does to us psychologically. However, watching people who look more like you powering through and succeeding, having the time of their lives, can be really empowering! For all his total cheesiness, Richard Simmons really got that; the backup people in his videos are a mix of old and young, men and women, slender and obese, but they're all working their butts off. Maybe try looking up "The Fat Chick Works Out" and "Heavyweight Yoga" as a starting point.
I'm assuming that, at your age, you probably don't get to choose everything you eat yet - at least some meals are prepared for you either at home or at school, or you may be limited by the groceries available rather than being the one to always do the shopping. So have an honest talk with your parents or whoever has influence over the food choices in the house, make sure they know what you're trying to do and ask them to support you by not bringing home the high-fat convenience foods, and instead filling the fridge and cupboard with better alternatives. Having healthy and tasty food available and easily at hand - and NOT having convenient access to the junk - can make a difference fast! I've only been cleaning up my diet for about three weeks and while I have lost some weight, more importantly, I feel way better. I have more energy and people who know me are telling me I look better. It's a cycle - eating better helps you feel better helps you exercise more helps you feel better helps you eat better and back around you go.
Especially if the only foods available arent' the best foods, really look at portions. Load up on veggies, and smaller portions of meats and starches and sugary foods. If your whole family is eating chips for movie night, take a handful into a small bowl and eat them slowly, allowing yourself to enjoy them as a "once in a while" kind of treat. Portions can make a huge difference - I've been taking a lot more notice of the portions my mom tends to dish out when we eat together, and in actual fact it's way more food than we really need. If I stay mindful, I can easily eat only 2/3 of what she gives me and be satisfied. I grew up in a pattern of eating mostly good food, but just too much at a time and way too quickly. Eating slowly and drinking lots of water while you eat can help you to listen to your body tell you when it's had as much as it needs. Be empowered to leave some on your plate or to ask for smaller portions.
Wow, big long essay there for you. LOL! Hope some of it helps, and good luck! You can totally rock this!