Helping Someone Close To Me

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I am trying to help someone close to me, lose some weight, but I don't know what else I can do or say. They are 72 years young, obese, had a quadruple bypass a year and a half ago, has diabetes and athritis in their back. They state that they mainly eat a few vegatables, and some fruit, and maybe a sandwich a few times a week. But, they are not losing any weight. They say, they also do yard work up to about 5 days a week.

I think they are not eating enough, but due to the health issues, not sure of what to offer in the way of exercise. Any suggestion?