I dropped off the face of the earth

First my college roommate dies suddenly, then my dad died slowly. It has been a rough 96 days away and I have gained 18 pounds.
A few days ago, I ran into someone who had lost 50 pounds in 4 months. I couldn't believe the change. He told me it was due to Herbalife and wouldn't you know it, he was a distributor. So now I am on day one of the Herbalife diet, but am already eating too little. I am supposed to eat 1399 calories a day and that just seems like a tremendous amount of food in addition to the two shakes. I don't know how to do it right without overeating. I need it written out for me, I guess, so there is no wiggle room.
Am walking to the gym three times a week with my husband, lifting weights there, and walking home.
I'd appreciate it if anyone has any advice regarding Herbalife.
THANKS!