I have been trying to lose weight for months.
I'm 18 and I'm a size 14.
I used to be a competitive gymnast and was a size 2 and 3 years later I have gained so much weight I had to buy new jeans every other month it seems.
I have tried by going on 30 minute walks daily and stopped drinking sodas altogether and have ended up gaining weight.
Is there any workout routines or programs or anything that can help me lose weight?
It sounds like you are going into the right direction with the 30 minute walks and cutting out the soda.
If you're not already counting your calories, I would do so now. Aim for between 1500-1600 a day. Try to eat as much veggies and fruit, make sure to have a healthy breakfast as it helps boost your metabolism for the day.
I personally do 45 minutes cardio 4 days a week, along with weight training. It took me a couple of weeks to work up to that much cardio, I started off with 30 minutes and then added 5 minutes every few days.
If you still enjoy gymnastics, it would be something fun to get back into. Though I don't know how much it would help with weight loss.
Is there any workout routines or programs or anything that can help me lose weight?
There are literally hundreds of things that you can do to lose weight, some more effective for you than others as it's a very individual process. There are thousands of posts on just this site about difference methods, approaches, what works, etc...
Here's the "program" I would recommend...
1. Get educated about how your body work, how weight is gained and lost, this can be done anywhere.
2. Read lots of ideas/tips/techniques, but ultimately realize that there is no magic formula that guarantees success for you.
3. Realize that it all points to one simple rule --- Calories In < Calories Out = Weight Loss
4. Build a plan that works for you to create a calorie defecit. This can be by reducing calories in (i.e. eating better) or by increasing calories out (exercising more, or more effectively). Preferably a combination of both. Plan should be designed to work within your personality, strengths/weakneses
5. Execute your plan
6. When you inevitably fail to follow you plan perfectly, get back on the horse quickly. Don't let a helping of greasy chips turn into the entire bag turn into a giant fast food meal turn into a day of non-stop binging turn into a week of old eating habits.
7. Do not get too caught up in what your mind thinks are appropriate results (i.e. 7 lbs by Valentine's day). Your body will change at its own pace based on the proper execution of your plan. Getting depressed that something doesn't happen when you think it should is a guaranteed way to fail since your idea of success is pretty arbitrary.
8. Celebrate success and think about and learn from failure
I have been trying to lose weight for months.
I'm 18 and I'm a size 14.
I used to be a competitive gymnast and was a size 2 and 3 years later I have gained so much weight I had to buy new jeans every other month it seems.
I have tried by going on 30 minute walks daily and stopped drinking sodas altogether and have ended up gaining weight.
Is there any workout routines or programs or anything that can help me lose weight?
I would start by writing down EVERYTHING you put into your mouth. This includes water, bites, licks, and tastes. You may not realize how much all these little things add up. Obviously water has no calories, but you should monitor how much you are taking in regardless.
How much fried food, creamy food, fatty protein, salad dressing, Candy, baked goods, are you taking in? Are you drinking any of your calories? I know you said you gave up soda, but what about juice? milk? alcohol? (I know you are only 18). Also, remember just because something says "fat free" doesnt mean it is good for you... sometimes they are loaded with sugar.
How many hours per day are you watching TV? All of these things can add up.
But I have another question, what kept you motivated to start loosing weight. Did you reward yourself with something small after a certain amount of weight loss?
Clothing! The very moment you try something on that actually fits ... bliss!
And I enjoy the process ... figuring, scheming, planning, trying exercises, shopping for food ... so a few days of appropriate work is a reward for me.
Go to a doctor and talk about this. Rapid weight gain from 15-18, if I am getting the timeline right, could suggest some sort of hormonal issue. If you went on the pill, see if you can get your doctor to switch you to a different one. You may also have a thyroid problem or PCOS. If there is a medical issue, understanding it will help guide your weight loss strategy. There won't be a miracle cure here--even if something is going on, you will still have to take the weight off, so pay attention to what everyone else is saying.
I went to the doctor 5 months ago, and asked questions about the thyroid history in my family, and if it could be affecting me and also I took a blood test and it came back negative.
He said since I had such a drastic change in workout times "I used to work out 35 hours a week " when now I'm lucky if I can get 5. That I should expect to gain some weight. But not as much as I have.
Maybe my metabolism is slowing down and I just need to really concentrate on eating healthier foods.
I went to the doctor 5 months ago, and asked questions about the thyroid history in my family, and if it could be affecting me and also I took a blood test and it came back negative.
He said since I had such a drastic change in workout times "I used to work out 35 hours a week " when now I'm lucky if I can get 5. That I should expect to gain some weight. But not as much as I have.
Maybe my metabolism is slowing down and I just need to really concentrate on eating healthier foods.
Yes, I believe healthy foods are the way to go. Lots of veggies, fruits, low fat proteins, no fat dairy... Make each and every item you eat a good choice. But counting calories is essential for me. I can without a doubt overeat the healthy stuff too and wind up not losing weight or even gaining. Calorie counting is built in accountability and forced portion control.
You can try fitday.com or one of the many other online calorie counting sites to get you started.
It's wonderful that you're thinking of this now, while you are young. The sooner you incorporate healthy eating (& exercise) into your life - the better.
Go to a doctor and talk about this. Rapid weight gain from 15-18, if I am getting the timeline right, could suggest some sort of hormonal issue. If you went on the pill, see if you can get your doctor to switch you to a different one. You may also have a thyroid problem or PCOS. If there is a medical issue, understanding it will help guide your weight loss strategy. There won't be a miracle cure here--even if something is going on, you will still have to take the weight off, so pay attention to what everyone else is saying.
I thought this was very well written.
I started taking BCPs at age 23 when I got married and gained 70 lbs that year without any real changes other than getting married. That's not a normal weight gain. I have PCOS. It's worth looking into because if you discover you have it, it's just better to be informed now. I thought Shmead wrote it out really well that there's no miracle cure for it, but it definitely affects the way we lose weight. And complacency is really bad with PCOS as far as weight goes. It's also important to know about because IF you happen to be insulin resistant (a common PCOS symptom), it puts you at risk for diabetes.
The test is a simple fasting glucose test. You don't eat or drink anything the night before and then at the doctor's office you drink a really sweet drink that tastes a bit like orange soda. You have some blood drawn and that's it.
How to Get Started
I would start by writing down EVERYTHING you put into your mouth. This includes water, bites, licks, and tastes. You may not realize how much all these little things add up. Obviously water has no calories, but you should monitor how much you are taking in regardless. 
