The short answer: No — at least not as much as the popular notion.
Many proponents of water fasting argue that it is possible to significantly slow down your metabolism by restricting your intake of dietary calories, or by reducing your daily caloric intake, or by simply by adopting a diet that includes a low percentage of carbohydrate and high amounts of dietary fat.  And indeed, research suggests that certain fasting strategies do indeed have these benefits. 
However, many of these techniques are unlikely to be a viable option for anyone looking to lose a few pounds, no matter how diet-friendly, since they can lead to a significant drop in overall energy and protein levels which would eventually lead to the loss of fat — which, in turn, may impair the metabolic process. In fact, researchers have found evidence that most of these approaches actually contribute to weight gain.
“Studies have shown that caloric restriction and weight loss diets can result in weight loss if dietary macronutrient intake can be maintained despite decreases in energy intake,” according to an article entitled “Effect of high-, low-carbohydrate, and low-fat diets on the glycemic control and body composition variables in overweight and obese men and women” in the JAMA Ophthalmology. “However, it was not clear whether these changes would be maintained over time.”
In other words, the only way to learn something from someone’s experience is to repeat it yourself so you can see if you’re on the right track. And since you’re looking at me, let’s assume you are: If you’re looking to lose a few pounds, it might actually be better to do it with very low calorie levels and to limit the carbohydrates you are consuming.
Does water fasting aid in weight loss?
If you’d like to know more about this approach and how it could help you lose weight, you can check out one of the many studies that have been conducted on the topic. For more information on the benefits of water fasting, check out “The secret behind water fasting: Is it possible to lose weight in a fasting state?”
However, there is still a lot of skepticism about the idea because there has been no scientific research that supports it. However, as we’ve mentioned before, water fasting is a relatively new weight loss strategy and is now available in many health food stores and on the internet. For example, a study published in July 2014 (pdf) found that for a month, people had reduced their carbohydrate intake after the water-
mayo clinic weight loss calculator, maintain healthy weight, how to lose weight fast in 2 weeks, improving diet, how to lose weight in 12 weeks