Nicholas Browning, M.D.: Calories, exercise, dieting myths
In my last column, I focused on the need to reduce calories to lose weight and explained it is difficult to keep up with the body and its metabolic adaptation to weight loss.
In this column, I’m going to write more about intake, exercise and dieting myths.
First, remember that achieving a sustained weight loss of more than 10 percent of your body weight is an excellent goal. Only 5 percent to 10 percent of body weight needs to be lost to gain large medical benefits such as reduced blood pressure and cholesterol.
For most people, that’s in the range of only 10 to 20 pounds.
Strict calorie counting is essential for weight loss, and I recommend programs like Weight Watchers, which make it easy to count calories and control intake. It is so easy to erase a 500-calorie deficit in one meal; without some sort of system in place to monitor intake, caloric limits will be exceeded.
If you look at people who have successfully lost weight using diet and exercise, they universally pay careful attention to how much they eat – including when they eat out.
The role of regular exercise in weight loss is less clear than many would like to believe. Most of our caloric expenditure per day does not depend on activity. About 85 percent of the day’s expenditure is spent running basic metabolic processes, and about 15 percent is due to physical activity.
In addition, exercise does not burn very many calories. A 200-pound person will burn about three calories per minute while walking, or around 90 calories for a 30-minute walk. If one walks five days a week, 30 minutes at a time, you’ll burn around 450 calories.
At that rate, it would take seven weeks to lose one pound. All it takes is one candy bar or dessert to erase most of the gain in a week!
The problem is that our bodies are quite efficient and are made to do a lot of activity with very little food.
Of course, we usually have very little activity but plenty of food available. This is not to say that exercise is unimportant in weight loss. There are suggestions that exercise preserves lean body mass (muscle and bone), and it definitely helps control blood sugar, blood pressure and cholesterol (though these effects are more modest than many would like to believe).
The consistent message from various studies is that exercise is more important for the maintenance of weight loss rather than weight loss itself. When you figure that walking one mile burns about 100 calories, you quickly see that you have to walk 35 miles (more than a marathon) to burn enough calories to lose one pound of fat.
The various benefits of exercise are in and of themselves worth it for everyone, but don’t expect miracles. Also, avoid the temptation to “reward” oneself for exercising; it takes very little to replenish what was lost.
Fad diets that encourage reliance on one food (celery, grapefruit), or exclude one class of calories (low- and no-carbohydrate) are not good for long-term weight loss. A healthy diet consists of a variety of foods from a variety of sources.
“Natural” products that encourage weight loss that claim to be safe are probably either ineffective or dangerous. Ephedra was used for some time in weight-loss products until several people died from it – and it probably took more people dying from it than was known at the time for the problem to come to light.
If a product is altering a person’s metabolic rate, then it is a drug – and deserves to be regulated the same as a prescription product.
The time of day that you eat does not matter. The body recognizes no difference between calories consumed at night and during the day.
Some people believe they have such slow metabolisms that it is impossible for them to lose weight. I have often heard that despite eating nothing, or close to it, a person will still gain weight.
The laws of physics don’t work that way. I cannot drive my car day and night, never fill the gas tank, and expect to find the tank more full than when I started. Someone is filling the tank! This is why strict calorie counting is necessary, because our perceptions mislead us.
Dr. Nicholas Browning is a Nevada County doctor. E-mail him at Nicholas.BrowningMD@gmail.com.
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