Ann uses 150 fewer calories by skipping tennis. She eats popcorn and chips, adding 500 calories. What has that done to her energy/calorie balance?
“Ann is studying for a health test. She had to cancel tennis after school because she needed time to study. But now she is bored. To help apply herself to her studies she makes a bowl of buttery popcorn. When that is gone, she gets a bag of chips from the kitchen. When she discovers she has finished off the bag of chips too, she is angry with herself. She had been putting on weight lately. Skipping tennis and eating all this junk food is going to add to her weight gain. She decides that she needs a plan to help her focus on studying without gaining weight.”
The sense of your question is that you wonder how much damage is done by ingesting 750 calories over and above your normal maintenance diet.
By focusing on calories you are recognizing how important they are in terms of maintenance of body weight. Exercise burns calories, and food contains them. And it is the net total calories ingested daily over time that determines your body weight.
Here are the most important basics that will allow you to understand and work with calories.
First of all, the human body requires approximately 15 calories per pound per day to maintain weight. This is true regardless of height or sex. A 200-pound man can eat 3,000 calories daily without gaining weight. If he exercises he can eat even more.
Second, when dieting, in order to lose weight at a recommended rate of one pound per week, you will need a daily deficit of 500 calories. So if your daily maintenance is 1500 calories, for example, you can lose one pound per week by a daily diet of 1000 calories.
Conversely, by ingesting 750 excess calories per day over time, Ann would be expected to gain approximately 1-½ pounds per week…not a good thing!
The reference provides a calorie calculator for women. It is very useful in formulating a weight reduction plan.