I have an obese client who I train twice per week for 30 min. sessions. Twice she has expressed to me that after our workouts she is so damn tired the rest of the day. We are only doing 30 mins and it consists of beginner exercises such as BW squat, res. band presses, & TRX rows. I review her food log weekly and her diet is very good, as well as her post-workout meal. I think a good part of it has to do with sleep issues.
You could suggest to her adding one more day of training with you. This will help her with getting in a routine sooner and improving her conditioning in a faster pace. The exercises you are prescribing here are not that much, so I’m not sure why she feels tired. Maybe those couple of times she must have had other things going on with her life or her mindset was not there. Adding some more cardio (more movement) in her routine could be beneficial.