I don't want to burst your bubble, but there's no scientific basis to the idea that HCG does anything to aid in weight loss; basically, all it does is fatten your doctor's wallet.
"Here's what the science says: Any super-low-cal diet will result in weight loss. Most studies have found that hCG (stands for human chorionic gonadotropin) has nothing to do with it.
The hCG diet limits you to 500 calories a day for 8 weeks while taking hCG, either by getting a shot or by taking a “homeopathic” product, such as oral drops, pellets, or sprays, which you can buy at the store.
None of this is approved by the FDA for weight loss. The shots themselves are legal, as long as a health care provider gives them to you. (They're approved to treat fertility issues.) But over-the-counter hCG products are not. The FDA has sent warning letters to several companies that market homeopathic hCG products."
http://www.webmd.com/diet/hcg-and-weight-loss
15-20 lbs in a months is not a very realistic goal, to lose weight safely and while you might be able to accomplish that with the phentermine, it's a pretty sure bet you won't be able to keep it off. Phentermine is not meant to be a long term medication, so as soon as you go off it and start eating again, the weight will come back.
Instead of trying to go on a crash diet, why not go home and stand proud, as the person you are today, not who you were 2 yrs ago?
A healthy diet with reasonable exercise will get you where you want to be; just not in a month.
I disagree with Barb about your goal being unrealistic. I did hcg drops a couple of years ago & stuck to the plan pretty well. I lost 38 pounds! Now, a warning to you is...stay away from junk once you are off of the plan. I started drinking soda & eating snacks & have gained about 15 pounds back (sooo mad at myself). Don't let naysayers discourage you...they've probably never even tried it. Everyone that I've ever known that has done hcg has lost the weight...& done it fast! I'd say go for it. Good luck!
Our goal here, is to promote safe weight loss by developing lifestyle changes so weight can be kept off over the long term and that's exactly what I stated -- that 15-20 lbs was not a realistic goal to lose "safely" and keep off.
It's not the HcG that causes the weight loss. Any diet that requires starvation will result in drastic weight loss.
There are all kinds of alternatives for weight loss; you can find them on the Weight Loss Alternatives forum, which can be reached via the following link:
http://www.medhelp.org/forums/Weight-Loss-Alternatives/show/80
The weight you lose with hcg can be safely lost...as long as you're overweight. The weight that you lose can be kept off...as long as you maintain healthy habits once off of hcg. The low calorie diet causes you to "tap into" your excess calorie bank...if you're well overweight, you don't need that much extra (as long as you're not stranded on a deserted island somewhere with no food). You are still eating enough to maintain energy. It's always interesting to see people claim that hcg doesn't actually "do anything", when it actually does. When you try a vlc diet with no hcg...you're starving! With hcg...you're not even hungry. In fact, I had a hard time even eating everything that was required of a meal. The food it suggests you eat are all " healthy" choices. Low cal. Low sugar. Low fat. I believe that it works because I've done it & so have many people that I know. Like I said, I've never known anyone that hasn't lost the so-called "unrealistic" amount of weight. If it didn't work or wasn't real, so many people wouldn't have the success that they've had with it...including myself. I felt good making the decision to do the diet & felt even better with the results. The original post asked for opinions...& I've given mine. I suggest that if you need to lose the weight fast...hcg is the way to go. Good luck with it.
I have done both diets. I lost 25 pounds with HCG alone in 1 month post pregnancy 2 years ago so it is possible. You really have to be strict and drink lots of WATER! In addition I used to work for a Wellness doctor and we did the HCG diet plan there and she would give patients the phentermine to help kick off the diet and help with the hunger. It works. Good luck and keep us posted!