Some hikers experience a problem on the trail: they eat too many simple sugars (like Starburst, lol, I've done it) not enough carbs, and they wind up feeling bloated and not so good. If you're sure that you've drank enough water on the trail but still found yourself having problems on the trail, you might want to consider taking more food, even if that means more weight.
Can it really take so many calories to carry one extra pound that it would cancel out the benefit of a pound's worth of extra calories?
Let's do the math. In general, backpacking food should be ~100 calories per ounce. Ideally, a pound of food should be 1600 calories.
For a list of some of the foods with the highest calorie amount per ounce, check this out: http://www.alsworldwide.org/pdfs/caloric_chart.pdf
And to figure out what you're burning on the trail, try inputting your weight in here: http://calorielab.com/burned/?mo=se&gr=17&ti=walking&q=&wt=150&un=lb&kg=68
By looking at what you're burning in a day for each weight versus what you're carrying, you can see that sometimes, a pound more of food can really be worth it. If, however, you're bringing around an extra 5 lbs of food, you'll be uncomfortable and really feel the difference.