Insulin pump vs. lantus
First, ignore that ridiculous BMI nonsense. I'm not on the pump and have no desire to go on one. If you are tired of being tethered to a pump I suggest going to injections. I don't mind them at all and they really fit my lifestyle. I am on Lantus and have not experienced weight gain with it. I did lose a lot of weight two years ago but that was a change if habit, not insulin. You have already identified the problem, just curb the snacking or pick snacks that are not conducive to weight gain.
I lost my insurance coverage and had to go off of an insulin pump and onto injections. I ran high the majority of the time that I was on Lantus/Humalog. I am also a forgetful, disorganized person. I hated having to turn around and go get the insulin/syringes. The tether is a difficult situation. You may find it easier to be on injections. The part of your post that unsettles me is the reference to weight. I read what you wrote after the title, however, and I see what you were talking about now.
The weight issue is frustrating to me as well. I have noticed that when my blood sugars are swinging up and down more that my appetite becomes unrealistic. When I have better control, my appetite gets mortal again. My weight also corresponds to how well I am in control. My insulin pump, while not ideal, has helped me to control my habits by helping me to regulate my blood sugars (still much more work to do) which in turn has a positive impact on my eating habits.
And high blood sugars will make you starve, if you're anything like I am. I'm in a stage where I am avoiding lows and conservatively regulating highs.
Whatever method you choose to treat your T1, good luck.
Oh, and ditto on the whole "BMI is nonsense" thing. It is.
the bmi thing is inaccurate. some people are more muscular wich is supposed to make your bmi higher i think.
BMI was developed by a Belgian scientist to study the application of statistics to sociology in the 19th century. It has zero to do with body fat and it based upon a theory of ideal weight based upon height.
Coming from someone in the dietetics field, I can tell you the BMI is used only as a guideline. There are multiple other factors that need to be taken into account to properly assess muscle, body fat, and "ideal" body weight (which truly doesn't exist... ideal is unique to every person).
It is very possible to lose weight on the pump, and could possibly be simpler on the pump because you can prevent lows easier, however how you choose to do it is up to you. Make sure you are checking frequently and keeping supplies with you at all times. Also make sure you are losing weight in a healthy way. You shouldn't drop more than 2lbs per week, and that is a maximum. And even if you aren't losing weight, as long as you aren't gaining you are making progress. Weight should come off slowly not quickly.
To lose weight, all you need to do is reduce calories by up to 500 per day. Because you are young and don't have a lot of weight you would like to do, I would recommend only cutting 250 calories per day. This can be done through consuming less calories and or exercising (burning calories). 30 mins of moderate exercise (gotta break a sweat) on most days (3-5 days) is the best, more if you like it. And it doesn't have to be 30 minutes all at once--3 10 minute increments work just as well! It all adds up to 30 minutes.
The key is NOT starve or deprive yourself and to pick activities you enjoy. If you like your forms of exercise, you are more likely to stick with them. Also, don't completely cut out any foods or food groups. EVERYTHING is okay to eat; what matters is how much of it you eat. I recommend keeping a food/activity log for a couple weeks. It lets you see your own patterns. Some people include their emotions in their log (how they feel when they are eating and exericse: happy, depressed, bored, annoyed, etc.) This also helps you see patterns in your lifestyle.
Good luck! You can do anything you put your mind to :o)