I would strongly recommend that you think twice and don't use this plan.
The potential risks and downfalls [of speed use] far outweigh the alternative.
Although reaching a weight "plateau" can be very frustrating and hard to break through, it can still be done with a bit of hard work, learning, and planning. (I'll expand more on breaking your plateau in a moment...)
I have no idea what kind of speed it is you plan on using, but any kind poses a great chance for potential abuse and addiction. Getting through a speed addiction will be a hell of a lot more difficult than breaking a weight plateau, and frankly, is not worth 12 lbs. Even if you promise yourself you'll use all the harm reduction tactics you can find, and you're "sure you won't get addicted," etc etc insert other positive outlooks and reasons to use here, fact is - speed is addictive, it sneaks up on you when you don't expect it, even in small ways. You can start small, using a very small amount and seeing "benefits." Next day, you wake up and go about your normal speed routine and find that it's not quite giving you that same spring in your step, you're feeling a wee bit lethargic and the number on the scale has halted again. Then, you'll add 'just a little bit more, just for now...' to get that same feeling and accelerate your weight loss goal again. Thus is the beginning of tolerance and addiction. It's not a good place to be.
Using speed for weight loss may seem easy and will likely help you reach your 12 lb loss quicker, sure - but that weight lost is likely not that of the fat you desire to lose, but will at first be excess water weight and then muscle. (I don't know where you're at right now, but if you started speed, the initial 6 or so pounds is likely excess water weight, and will aid in tricking you that you're losing that fat you want to shed.)
You said you "train hard and eat healthy." This shows that you definitely have the fire & desire to reach your weight loss goals, and also shows that you have probably already put in some serious time and hard work. Well, if you want to see that hard work go out the window, then by all means, start up that speed. If you don't want to see your blood, sweat & tears go down the drain, I suggest avoiding the speed and using different ways to break your plateau.
To break a weight plateau will require you are more restrictive and closely monitor your diet. If this is something you're already doing, you need to start "confusing" your body and switching things up (with your food and with your workouts.) If you have a specific routine down, it's time to make a new plan. If you're a runner and 90% of your workouts consist of running, switch to swimming. or rowing. or circuit training. anything but running. If you workout 5 days a week, and you are a runner, switch it to only one of those 5 days is running, and find new high-intensity cardio activities. Each different activity uses different muscles and parts of the body, which can kick-start weight loss and/or break through a plateau. Also, make sure that you are weight training as well. When I hit a plateau weight that I was trying to break through, I was working out 6 days a week, mostly cardio (everyday) and weight training 3 days a week. I switched it to 5 days/wk of strictly weight training, and 1 day/wk of cardio, a different cardio every week. I broke through my plateau rather quickly at that point, and it felt amazing.
Regarding your diet, you'd basically do the same thing I said above with the switching up types of cardio - switch up the kind of food you're eating. If you are eating basically the same thing every day at every meal, no matter how healthy, it will be more difficult to break through the plateau. If you're eating eggs and toast every morning, switch up to oatmeal and an apple. If you have a chicken salad for lunch everyday, switch up your proteins to tuna, salmon, steak, etc. Expand your food tastes as far as you can take them. Explore new foods and try not to eat the same thing twice in a week (breakfast being an exception, at least for myself...I am a picky eater and found it a bit difficult to find 7 different and unique breakfasts, but I explored as many as I could and rotated them and modified them as much as possible.)
The combination of "shocking" your body and switching things up leads to a great potential to set yourself up to break through your plateau and reach your weight loss goal. This way, as opposed to hitting the "easy" button and using speed, is infinitely more likely to help you keep your weight off in the long run, sustain a healthy lifestyle, and avoid that pesky thing called 'addiction.'
