Help with my obese friend

One of my very best buddies is very overweight (around 300) and a smoker and is at the end of his rope in terms of his health. He wants to change and asked me for my help.

What kind of cleansing do you think I could start him on right off of the bat? I know he couldnt handle a fast at this point because he is so toxic it would make him misserable.

How do you think I should start him off in the right direction?