Fruits and vegetables and fruits will help you lose weight.  

Fruits and vegetables at a farmers market

Americans, in general, eat too few fruits nad vegetables.  Fruits and vegetables have several benefits that make them exceptionally beneficial for those trying to lose weight.  They tend to have more fiber than fruit juices but still have the vitamins you need.  

Fruits and vegetables are full of anti-oxidants, vitamins, and minerals[1].  They are less dense in calories and have lots of fiber and are rich in water which results in a lower energy density and slows the absorption of the calories.  They also take a lot of effort to chew and are quite filling.  Besides nutrition, there are also weight and body fat effects.  

Research on fruits and vegetables:

Low levels of fruits and vegetables increase the risk of obesity.  One great study from 2009 by Buijsse found that weight and fruit and vegetable consumption are inversely related[2].  So, in other words, the less a person eats of fruits and vegetables, the more likely they are to be obese.  In fact, they found that for each 100 grams of fruit and vegetable intake per 24 hours resulted in 14 grams of less weight gained.  Another study that confirmed was performed by Ledoux in 2011 and found an inverse relationship between the serving of fruits in vegetables in your diet and obesity[3].  This makes sense because vegetables then to slow digestion with their fiber and if a person does not eat many servings of fruits and vegetables, they are probably replacing it with starches and fats which are more likely to pack on the pounds.  Other studies have also found this relationship and I have yet to find a single professional that feels increased vegetables and fruits will not reduce your risk of obesity[4],[5].