The idea of vinegar helping with weight loss isn't a new one. In fact, this fad diet has been around since the 1820s, when the poet Lord Byron was a proponent of drinking vinegar and water. This doesn't mean that it's necessarily safe or effective, however.
Lack of Evidence
A review article published in American Family Physician in 2004 noted that apple cider vinegar is among the supplements commonly used for weight loss, but that it hasn't been well-studied for this purpose, so it should be used with caution under a doctor's supervision. Proponents claim it can suppress your appetite, thus helping with weight loss, or that it promotes fat burning. However, Columbia Health notes that, at most, vinegar may cause you to lose water weight. It doesn't affect fat.
Drinking straight vinegar is unhealthy because it can erode the enamel of your teeth, irritate your throat and interact with insulin, diuretics and blood thinners. A safer way to increase the amount of vinegar in your diet is to use it with olive oil as a salad dressing or to mix a small amount into a full glass of water. Both of these will limit the acidity of the vinegar as it goes through your digestive tract, making throat irritation less likely. Drinking your vinegar water with a straw can help limit contact with your teeth and thus erosion of your enamel.