I agree with the other posters who said Slim Fast is not the way. That stuff is all kinds of evil. It is junk food in disguise. Weight loss is hard work, dedication, determination, and hard work! :) It actually needs to be a combination of eating right, exercise, and changing your mindset. It's not a diet, it's a way of life. These are the steps I would recommend:
1. Set realistic goals - 1-2 pounds a week is realistic. Anything more than that is not safe, and you may be losing muscle.
2. Make sure you are eating enough calories. Find out what your metabolic rate is so you know how many calories you should eat to lose, and how many you should eat to maintain. Here is one site you can go to: http://walking.about.com/cs/calories/l/blcalcalc.htm I just did a quick Google search to get to this You should do your own research.
3. Add resistance training to your workouts. Cardio alone is not sufficient if you want to lose fat. Lifting weights 2-3 times per week for about 20 minutes a day should do it.
4. Make sure you are eating a healthy balance of foods. You need protein, healthy carbohydrates, and healthy fats to lose weight. Yes, fat. Healthy sources include nuts, flaxseed and fish oils, nut butters, etc. Cut your sugars and avoid high fructose corn syrup.
5. Get a skin caliper or a scale that measures body fat percentage. You need to make sure you are losing fat, not muscle. The number on the scale is not the only thing that matters. You can be 5'4" and weigh 130 pounds and think you are healthy - but if 40% of your weight is fat, you've got a problem. Think "fat loss", not "weight loss"
Finally, I'd just like to add to the person who said they've never seen a fat vegetarian...I want to know where you live! LOL! I have been a vegetarian my whole life, but even though I choose not to eat meat, and I eat a plant based diet, I still struggle with temptations just like meat eaters do. :)
Someone who gave me inspiration was a body builder named Tom Venuto. He has helped many people lose weight successfully, and helps you to look at diet as a lifestyle, not a quick fix. He has written two books, "Burn the Fat, Feed the Muscle" and "The Body Fat Solution". It is not for everyone, but it helped me. Good luck!