Testing for non-BLANK returns incorrect result

[Nicole_Hillborn]

Help! I'm trying to get an estimated calorie count using workout time, weight, and intensity. My workout time field is a lookup field formatted as duration. The weight is 160, the duration is 39:00 and it is moderate intensity. The formula is returning 16,770 instead of 279.5.  What am I doing wrong?

Original formula:
IF({Workout Type} = "Primary", IF({Workout Intensity} = "Low-Intensity", {Primary Workout Duration (Minutes)} * (4 + (({My Current Weight} - 125) / (185 - 125)) * (6 - 4)), IF({Workout Intensity} = "Moderate-Intensity", {Primary Workout Duration (Minutes)} * (6 + (({My Current Weight} - 125) / (185 - 125)) * (8 - 6)), IF({Workout Type} = "High-Intensity", {Primary Workout Duration (Minutes)} * (8 + (({My Current Weight} - 125) / (185 - 125)) * (12 - 8)), 0))), 0)