In my last post, I shared a Ted presentation on dieting and weight loss. In that post, I repeated Dr. Sandra Aamodt’s premise that losing weight may cause the hypothalamus to slow down a person’s metabolism, making it very difficult to maintain a weight loss. I thought I should clarify the terms “dieting” and “metabolism” in this post.
To me, the term dieting means deliberately restricting calories to achieve weight loss. For example, if someone decides to only eat 1200 calories a day, that person is “going on a diet.” It makes me think of someone carefully planning each meal, recording how much he or she ate, and obsessively watching the scale to keep track of weight loss. It involves food deprivation, frustration, and suffering. Worse, dieting can lead to an eating disorder and an unhealthy obsession with food. Will dieting cause weight loss? Yes, it will, but it usually doesn’t translate to a lifelong victory over excessive weight. In fact, a person is likely to go through all that effort, only to see his or her weight eventually go back to what it was before, or even higher.
Metabolism refers to the sum of all the chemical reactions that occur in your body. Catabolic reactions break down larger molecules into smaller ones, and anabolic reactions build larger molecules from smaller ones. Think about what happens when you eat a bowl of oatmeal. Chemical reactions break down the complex carbohydrates in the oats you eat into smaller glucose molecules, using catabolic reactions. The glucose molecules that aren’t needed for your immediate energy needs get strung together to form a larger molecule called glycogen, using anabolic reactions. Millions of other chemical reactions occur in your body every day. You must make and secrete hormones, repair body tissues, get rid of wastes, process sensation, move body parts, and so on. The speed at which all of these chemical reactions occur is your metabolic rate, and you use the energy in the food you eat for these chemical reactions. If your metabolic rate is fast, your chemical reactions occur at a faster rate of speed, and you burn more calories. If your metabolic rate is slow, your chemical reactions occur at a lower rate of speed, and you burn fewer calories.
I hope you can now why severe caloric restrictions are not a good idea. They slow down your metabolic rate, causing you to burn fewer calories. When you go back to eating your usual amount of food, weight gain results.
To learn more about metabolism, here are two sites I recommend. One is designed for children, but I think it’s a great one for adults as well:
In my next post, I’ll talk about ways you can keep or increase your current metabolic rate.