Hi Jean Anne. In my opinion, there is no right or wrong answer here. You use what works for the particular client that you’re working with. I think that too often in our profession people subscribed to a singular methodology or school of thought on how to train a certain class of clients or demographic and they use that same method with all clients in that demographic whether or not it’s the best for that particular person.
I have trained lots of overweight and obese clients and have had great results by challenging them within their own personal abilities. Remember that all humans, and that and that includes the overweight, improve their strength, health and fitness through the “Overload Principle.” Applying that principle entails a methodical and progressive increase in the intensity of exercise over time. In the instance of your question regarding the use of weight, this means that overtime the person will use progressively heavier weight (of course to a limit) as well as being ‘overloaded’ or challenged in other ways such as increasing workload through increased repetitions or sets etc.
I published a short article on this very subject and would be happy to share it with you if you send me your email address.
I hope that this helps.