Gaining weight...

I just want to say that stationary bikes are BRILLIANT for muscle. I've been riding one for the last 3 weeks or so in an attempt to lose weight, doing 1 - 3 miles a day at around 15 mph. I'm losing fat, not weight - I have packed on the muscle so much so that the scales haven't changed, though it's easily to see the changes already. My stomach, arms and legs all ache in the good kind of way. To up the ante, I keep my arms bent, lean over the handlebars a little, and tense my stomach.

Walking is good too, but you should try power walking as the exaggerated movements of your arms will really help.

Oh poor girl! I (kind of) know what you're going through.
DH & DD are both terribly hard keepers. DD simply WILL NOT gain weight, just keeps getting taller and taller. DH is 6'3 and weighs twenty pounds less than I do and I'm only 5'2... He also has digestive issues due to his terrible diet when younger and genetics.

Sooo... If you were my kid I'd start with:
Prenatal vitamins stat. Have you had your iron levels tested?
You skinnies with your metabolisms need foods that are high in calories, and super rich in omegas. Get to cooking lots of brown/white rice. Rice helps stabilize/slow your digestive system.
Top your foods with beneficial oils like fish and hemp seed oil.
Eat three BIG meals a day. This will help you slow your system.
For added nutrients and to get your vegetables in, purchase one of those food processors (Nutribullet) and be sure to mix in nuts and the healthy oils. This is a yummy way to get your vits and minerals in without having to choke down raw veggies.
Snack on high calorie granola bars, oatmeal, crackers and cheese.

Go to a natural herbalist. There are all kinds of shakes and mixes that will help you add weight, but in a healthy way. You need lots of protein and complex carbs to sustain your fast metabolism. Mix a scoop full in your veggie shakes to make them sweeter.

I cook DD & DH three meals a day, mix them shakes, they eat from the time they wake up to the time they go to bed. Looking at them you'd think I wasn't a very good cook! LOL!! I know it's a struggle for you, hugs!!

I'm also 5'7" and was once 102 lbs. That's pretty skinny. Protein helped me put on healthy weight in the form of muscle. Hopefully you eat meat. That's the quickest way to get there. Also, if you're like me and eating a big meal in one sitting just ain't your thing, those weight gain drinks are great to have on hand, particulary the protein based ones. Boost and Ensure are both good ones. Drink those instead of soda, and you'll be well on your way.

Glad you're addressing this now while you're young. If you stay too skinny for too long, you might develop brittle bones and have to stop riding in your later years which would suck.

Basically any food you prepare is nutritionally sound if not way over cooked. Very few foods your body needs comes in a box, even instant oatmeal. The oatmeal you cook is better as it hasn't been exposed to the high heat the instant has in the mfg. Process.

First you need to find what your daily caloric intake should be in accordance to your activity level and your current BMI. Try tracking your calories to make sure you are eating enough HEALTHY food. You would be surprised at how much healthy food you can eat :) I use MyFitnessPal on my Ipad for my calorie counting.

Try some of the recipes on the WOmens Health Magazine website. THey have some good recipes as well as articles for gaining muscle mass which is the weight you want to gain.

Eat fresh foods. The frozen microwavable steam vegetables are amazing for this. They have few preservatives in them and are delicious and fresh since they are frozen within hours of being picked.

Personal favorite: marinated Hawiian chicken grilled with a slice of grilled pineapple and brown rice= amazing

Have you seen a doctor for a routine check up? The reason I ask is I'm a nurse, and your issues could be related not just to your diet but metabolic issues. I'd suggest that you go see a doc and have some routine bloodwork done. They can also make educated suggestions about how to improve your diet and gain muscle mass safely

I actually had bloodwork done and they said everything was fine. I've actually found that when I become exhausted it's the day after I eat a lot of sugar-y foods. :S The cookies and what not is the challenging part for me to quit, but it's getting better. XD

So, they still think it's diet and I won't be able to tell whether or not until I force myself to stay (and I mean continue daily) on an exercise and absolutely no junk food regime.

But as said, it's slowly getting there.

And thank you everyone for all the advice! I do appreciate it(:

The only way I can gain weight is thro weight lifting. The routine was any 5 days a week, just couldn't miss two in a row. Three days will do it but I wanted it to be part of how I lived my life. Others things do come along so taking a day off actually gave the muscles a chance to recoup. My warm up was always 15 min on the stationary bike then thirty minutes of weights. This was divided in to 15min for upper strength and 15 for lower. Women often use the excuse to not lift weights by saying they don't want to be built like a man. We don't have enough testosterone for that to happen but it's sure nice to look like a trim and fit woman.

Do you know what tests they did? If it were me, I would have wanted a CBC, chem panel and TSH.

I don't know what your grocery store situation is. I have one in town, and the selection of produce is usually not great. I go get whatever they have that looks like quality produce, then figure out how to cook it. Allrecipes.com lets you search by ingredient. Learning a few basic techniques for cooking vegetables also makes them taste so much better than I remember as a kid, LOL.

You can also get creative at sneaking veggies into your diet. Omelettes (or in my case, egg muffins, because you can bake a big batch and refrigerate for a week and heat and eat as needed) are great for that. Cowboy caviar has veggies and beans. One of my favorite snacks is half an avocado with a little Dorothy Lynch dressing. Cottage cheese with tomatoes and bell peppers. Stuffed mac and cheese is great, too.

As far as getting in shape, I would recommend alternating weight lifting with walking. Resistance training is so important for bone health, especially for women. I would also recommend several short stretching sessions every day. Yoga is good too, particularly for core strength, which really helps when you ride.

Firstly, I'd like to thank everyone for posting and giving advice, tips, opinions, etc. I really appreciate it!

I consulted with my doctor and we came to the conclusion that it was merely dietary. My junk food diet just wasn't cutting it. As long as I don't overdo the junk food and sodas I feel energetic and overall better. I am taking a few vitamins as I'm a bit small and have never been one to eat a lot. It's more of a "just in case" kind of thing. I'm also considering going to one of the local gyms to start working out on top of my riding lessons as well as considering yoga (in the house workouts, etc).(:

Again, thank you for all the comments!