Not only does the trend let you balance your calories, it's a tireless sentry that notifies you of emerging weight problems while they're still easy to correct. Suppose you just printed a trend chart like this one.
Clearly, a dramatic change in calorie balance occurred in the last three weeks of this month. This rapid climb, starting from the goal weight of 150 indicates an immediate need to reduce your calorie intake by about 350 calories a day (the 329 excess shown in the chart plus a tad more to cause a slow drift downward to 150 pounds). Since you were eating too many calories and gaining weight, cutting back to slightly fewer than what you're burning should not leave you hungry, as your daily deficit will still be less than 100 calories as you return to the goal.