According to WebMD as of February 2015, one to two tablespoons mixed in a large glass of water will help to lose weight. Eating healthy and exercising in addition will help one to lose weight.
WebMD also states that the only place this was tested was in Japan. In the study, 175 people took 12 weeks to lose one to two pounds. Once they had stopped drinking the vinegar, all the weight was gained back. The effects of drinking the vinegar are very subtle and are definitely not a quick fix. If you want to lose weight, exercise and portion control are recommended.
WebMD also states that there may be some connection to drinking apple cider vinegar and lower blood sugar levels in diabetic patients. However, they also continue to say that a balanced diet has more research behind it, and is the recommended way to control diet.