The Dynamics of Weight Control
The Dynamics of Weight Control - If you are over age 35, or you are short in stature, or youíre a woman, itís not your imagination that it is harder for you to maintain a healthy body weight! Height, sex, and your age play important roles in determining how many calories you need to maintain your body weight. How many times have you heard people say that they canít eat the way they used to? Or, ďWhen I was 20, I never had to watch my weight.Ē Yet, these same people at age 40, are fighting to lose 20 or 30 pounds. Letís take a simple example of how calorie needs change with age, and how it is so easy to gain weight in adulthood.
The Numbers Add Up
Example 1: A woman, age 20, 5í4Ē tall, 125 pounds, average physical activity. Calorie needs: 1700/day
At age 30, this same woman would need 1650 Calories to maintain her weight, and at age 40, she would need 1600 Calories to maintain her weight of 125 pounds. So, over a 20 year period, gradually, she needs about 100 fewer Calories each day to maintain her weight. Thatís a small difference over time, only a change of about 5 Calories a day for each year after age 20. Thatís if her physical activity stays the same.
So, some people find a way to gradually adjust their calorie needs with age so that they eat slightly less, or they increase their physical activity to make up the difference, and their weight stays the same.
For many people, though, gradual weight gain occurs instead. How does this happen? Well, if the woman in this example failed to modify her calorie intake, by the time she reached age 30, she could have added an extra 10 pounds, and by age 40, perhaps another 10 pounds, her weight creeping up with each year. This is because metabolically, we slow down with each passing year of adulthood, needing fewer calories to maintain our body functions. Itís a small difference each day, perhaps the caloric equivalent of a piece of hard candy, but it adds up slowly over time.
In fact, about 70% of our calorie needs go to just maintaining body functions. Only about 30% is needed for moving and extra physical activity. But, that 30% makes a big difference - just take a look at what happens when a person reduces their physical activity and grows older! If the same woman at age 20 followed a program of some kind of regular physical activity that burned about 150 extra Calories four times a week, then stopped her exercise plan (injury, kids, change in routine) and didnít change her calorie intake, she could gain 9 pounds in just one year! This is why injuries can lead to weight gain so quickly - lots of sitting, and probably more eating, with no way to compensate for it.
Well, enough about getting older! Gaining weight is not inevitable with age, but if you add in reduced physical activity, itís easy to see how so many adults gain an extra 20 or 30 pounds, without really changing much in their intake of food. Now, letís look at height and sex, and how that affects calorie needs.
Example 2: A woman, age 30, 150 pounds, 5í5Ē, average physical activity. Calorie needs: 1824/day. Now, a man, age 30, 150 pounds, 5í5Ē tall, average physical activity. Calorie needs: 2040/day. Thatís a difference in this case of 216 Calories per day, just for the metabolic differences between men and women, regardless of age, weight, or height! These calculations are pretty accurate, but there are certainly individual differences. One of the reasons that men get to eat more to maintain their weight is because the normal body fat percentage for a man is about 12-20% of total weight, while a normal body fat percentage for women is 20-30% of total weight. So, for a man and woman who weigh the same, and have a healthy body weight to begin with, the man will have a greater percentage of his weight as lean tissue because his body fat is lower. This lean tissue is what creates the need for more calories.
While this seems a little unfair to women who are trying to lose weight, this difference in calorie needs shows why a man can lose weight a little more quickly than a woman. However, if the woman who weighed 150 pounds in the example above was very lean due to physical activity, you can bet that her calorie needs would be much closer to the manís. The take home point of this is from a caloric point of view, it is very important for a woman to burn calories through safe and moderate exercise, to build lean tissue instead of just reducing calories. This, in turn, allows you to maintain a healthy body weight and eat more food at the same time. For men, it is equally important to exercise to burn fat and to retain lean tissue when you follow a ďdiet planĒ to lose weight, so that you donít lose the lean tissue you already have!
Understanding that your age, sex, and height all play a role in how many calories you need may help explain a few things, but you canít do anything about them. Genetically, we can only get so tall, we canít stop aging (yet), and not many people choose to change their sex. But, you can do something about that 30% - the percentage of calories attributed to moving around and exercising. The more you move, the more you can affect your calorie needs, so that you can enjoy a reasonable amount of food without gaining weight. Moving around to burn an extra 100 or 150 Calories three or four times a week may seem small - the equivalent of only about 2 slices of bread, or one beer, a few cookies, but over time, it really makes the difference.
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