Lemons may help you lose weight.  

Lemons are rich in polyphenols which are naturally occurring antioxidants.  Each citrus fruits have their own polyphenols combination, and the ones in lemons can have significant health benefits.  Who would have thought that a little lemon in water would have a positive benefit in weight loss?  We know that water helps, but does lemon in water have an additional benefit.  

I study from 2008 that was published in the Journal of Clinical Biochemistry and Nutrition looked at lemon polyphenols and weight loss​[1]​.  The aim of the study was to investigate the effect of dietary lemon polyphenols on high-fat diet-induced obesity in mice.  It would be better in humans, but it is all we have.   Mice were divided into three groups and fed either a low-fat diet, a high-fat diet, or a high-fat diet supplemented with 0.5% w/w lemon polyphenols that were extracted from lemon peel.  The mice were followed for 12 weeks.  Bodyweight gain, fat pad accumulation, the development of hyperlipidemia, hyperglycemia, and insulin resistance were significantly suppressed by lemon polyphenols. 

The bottom line:  Supplementation with lemon polyphenols appears to suppress body weight gain and body fat accumulation.  More research is needed, and human trials are needed, but lemon polyphenols show promise.  Supplementation with lemon polyphenols may prevent or improve obesity and insulin resistance by modulating lipid metabolism and preventing metabolic syndrome.