Like yams, sweet potatoes have a good glycemic index ratings.
1. Preheat oven to 350ºF.
2. Peel sweet potatoes and mash pulp. Add juice, ginger, nutmeg, and grated zest.
3. Beat egg whites until stiff peaks form and fold them into sweet potato mixture. Spoon into a 1-quart nonstick baking dish and bake for 30 minutes.