Here is the full list of all 51 Get Fit With Mel B trophies - there are 41 bronze, 7 silver, 2 gold and 1 platinum.
Reach level 70 in three categories
Complete a Cardio Workout
Complete a Pump 'n' Tone Workout
Completed 1000 reps
Reach level 70 in any category
Reach level 60 in any category
Complete a Dance Workout
Burned off a chocolate bar
Completed 500 reps
Created a Custom Fitness Workout
Won a gold medal in a workout
Complete a Combat Workout
Completed your first Workout
Completed 100 reps
Done 10 perfect reps in a row
Done 20 good reps in a row
Collect all other Trophies on Get Fit With Mel B
Done 1000 press-ups on toes
Done 1000 long-arm crunches
Raised any category's Fitness Level by 10
Raised any category's Fitness Level by 25
You have exercised every day for two weeks
Collected over 350 Stars in a Dance Aerobics Workout
Climbed the equivalent of the Empire State Building
Lifted the equivalent of a SUV in Pump and Tone
Got a gold medal for all challenges
Burned off a pizza
Burned off a Christmas dinner
Followed the menu every day for a week
Completed a 60 minute Aerobics Workout of any type with a score over 90%
Practiced five different exercises
Completed at least one workout of each workout type
Created a Custom Aerobics Workout
Completed an Aerobics Workout between 12:00am and 2:00am
Completed a Fitness Workout between 5:00am and 7:00am
Complete a Fitness Workout
Complete an Advanced Cardio Workout
Complete a Step Workout
Complete 20 Fitness Workouts
Complete 20 Dance Workouts
Complete 20 Cardio Workouts
Complete 20 Advanced Cardio Workouts
Complete 20 Step Workouts
Complete 20 Combat Workouts
Complete 20 Pump 'n' Tone Workouts
Reach level 80 in any category
Reach level 90 in any category
Reach level 100 in any category
Reach level 80 in three categories
Reach level 90 in three categories
Reach level 100 in three categories