In a gallon size glass jar, stir together sugar and just enough hot water to dissolve the sugar.
Add the lemon juice and fill the jar about ¾ full with filtered water.
Make sure the liquid is at room temperature and then add the whey.
Cover tightly and let sit on the counter for 2-3 days.
After 2-3 days, keep the lemonade in the refrigerator and drink 4-6 ounces per day. The flavor will continue to develop.
Since the sugar ferments out, it is rather tart. Add a couple drops of stevia if it is too tart for you!
You can add about 1 teaspoon of molasses to the sugar before dissolving to add extra minerals and a bit more sweetness. Blending the final product with ice cubes will make a delicious slushie (or margarita if you're using limes!).