5K or Stop Overeating

I joined scholars with 25-30 pounds to lose.
I have signed up to run my very first 5K race that will be in mid May but after watching the Stop Overeating workshop I understand that Brooke advises not to exercise until we lost all the weight.
To be able to run the race, I need to run at least 3 times per week as well as supplement with 3 more days of some strength training.

What do you suggest I do? Must I choose either or?