My mom is 58 years old and has been very overweight for as long as I can remember. She's 5'9 and is probably over 250 lbs.

I've been preparing all of her meals, oatmeal or an egg with whole wheat toast and fruits for breakfast, and lean meats with lots a veggies and occasional starches for lunch and dinner. Sometimes I treat her to occasional low cal desserts or healthy versions of her old favorites (like pizza, ie THIN crust with low fat mozz and veggies). Over the past few months, she's gone from a size 24 to a 20.

I've recently started her on a bit of exercise on our stationary bike. I started her at 2 minutes and we've worked up to 10 mins.

My question is, what amount of exercise is appropriate for her? She hasn't got any health problems except high blood pressure (due to being overweight!) How many minutes should we work up to and how many days a week should she do it?

Also, does her diet sound okay? I want her to be healthy so she can have a long, wonderful life!