Will eating a vegetarian diet for 30 days, jumpstart a significant weight loss?

Yes, and... This is a great way to end unhealthy eating habits. Vegetarian fare isn't as greasy / sugary / salty / yummy as the stuff that most of us overeat. Even better -- why not "jumpstart" a whole new lifestyle based on fitness-based activities, as much a choice-of-friends issue as anything? They'll guide you on reprogramming your mind and body for a far better life long-term.