I would agree with Nancy Kay... Soy milk is a healthy drink (in general) but making it the entire source of your meal will lead to vitamin / mineral deficiencies. There are only about 150 calories per serving so you'd have to drink an awful lot of soy milk.
For weight loss, you should consider eating 6 small meals spread throughout the day. The bigger meals should come earlier in the day when your metabolism is higher. Restricting your food intake will reseult in slower metabolism and ultimately weight gain.
Be sure you are exercising and use a website such as http://www.fitday.com to track your calories and exercise intake.
Feel free to drop me a line if you need further help.
Good luck.

soy milk is a milk replacement. not a MEAL replacement...in essence you just asked is a glass of milk a good meal replacement for weight loss, and of course, the answer is NO!

.....I have no idea but I LOVE SOY MILK!!!!!!!! Number 1 drink >.<
and by the way, I only gain from it......lol