I'm beginning a lifestyle change with a low carb high protein for improved fitness and weight loss . what is a good sweetener, for say plain yogurt?

Fruit eg berries: Congratulations on your decision to improve your health. Don't forget to include exercise (strength, aerobic & flexibility) in your plans. Try greek yogurt rather than regular plain yogurt. The greek kind has more protein. As for sweetener, i like to add various berries to plain greek yogurt. Some like to use agave syrup but don't get too caught up in those details. Focus on the big health picture.

Slightly different..: Greek yogurt is better than regular (unless you can get kroger's carbmaster. Go with two percent, without it beeing preflavored. There is more milk sugar in the 0% fat greek yogurt. Berries then can be added. I would sweeten with sucralose or splenda!