Why People Gain Weight, and What To Do About It

Mature man with big belly struggling to put pants onIt’s well known that obesity is epidemic in this country.  Unfortunately, there doesn’t seem to be much agreement about its causes and cures.

While it might seem obvious that overeating causes overweight, a recent article in the New York Times (Always Hungry? Here’s Why) explains that one reason people overeat is because they are overweight.  Once you have excess fat cells, they start absorbing the calories you eat, leaving your bloodstream low on calories and continuing to crave more.

The authors, David Ludwig and Mark Friedman, explain what happens when fat cells store the extra calories.  The brain notices fewer calories in the bloodstream, so it tells the body to increase intake (so we feel hungry) and to save energy (so our metabolism slows down, burning calories more slowly).

Other causes of weight gain include stress, reduced physical activity (such as sitting at a computer all day), lack of sleep,  many medications including psychiatric and diabetes medicines, and genetic tendencies.

Additionally, being told you are fat (even by well-meaning parents) can actually make you gain weight.  A recent study, published in a medical journal for pediatricians (JAMA Pediatrics, “Weight Labeling and Obesity“), found  that if a child is told she is “too fat” by her family members, she is more likely to be obese by the age of 19 than is a child of similar weight who is not stigmatized by the “fat” label.

It’s pretty hard if not impossible to change these factors, so is there any hope at all for people who want to lose weight? Diet books and articles are everywhere, and many of them see m to contradict one another.  The authors of the New York Times article, Ludwig and  Friedman, who also published their findings in the Journal of the American Medical Association (“Increasing Adiposity: Consequence or Cause of Overeating?“), offer a few guiding principles.

They explain that weight gain is triggered by excess insulin, and that highly refined carbohydrates produce the most insulin.  So, they explain, it’s not true that all calories are equal.  It’s better to avoid certain kinds of calories: specifically, those from refined carbohydrates including sugar, flour, and white potatoes.

Whole grains, and certain starchy vegetables such as boiled sweet potatoes, are a better source of the carbohydrates we all crave and need as part of a balanced diet.  Surprisingly, whole wheat bread and brown rice may not be particularly lower in glycemic index (a measure of how quickly carbs are converted to glucose).  Instead, eat whole grains such as barley, millet, quinoa, wild rice, or cooked whole wheat berries.  Dr. Andrew Weil explains more about glycemic index in this article on his website.

It is likely that fat slows the absorption of the carbohydrates, which prevents a spike of insulin in the blood, leading to less of the glucose being stored in fat molecules.

Furthermore, fructose (from table sugar, honey, maple syrup, agave and high fructose corn syrup, among other sources), is even more toxic than other carbohydrates.  Fructose is metabolized down the same pathways as alcohol. Thus it, like alcohol, can cause fatty liver disease, and eventually cirrhosis of liver and liver failure.   You can hear a lecture by Dr. Robert Lustig on the dangers of sugar here.

Doctors and nutritionists all seem to agree that vegetables are good for you, especially fresh vegetables, and that protein is important, though there is room for disagreement about the value of animal proteins (meat and dairy).

And given a choice between a “low fat” product, which is likely to contain extra sugar to make up for the loss of flavor, and a full fat product with less sugar, choose the latter.  It may be that one more cause of the obesity epidemic is the spread of “low fat” processed foods over the past few decades.  Although no one advocates eating slabs of butter or deep fried foods to lose weight, we all do need some healthy fats in our diet.

It turns out that a higher fat, lower carb diet may help with weight loss.  Ludwig and Friedman point to another study showing that dieters burned about 325 more calories on a low carb diet than did others who followed a low fat diet, even though both diets involved eating the same number of calories per day.   They also cite animal research: a group of rats who were fed a diet of highly refined carbohydrates gained 71 percent more fat than did rats who ate less refined carbs – even though the  rats on the whole-grain diet consumed more calories overall.

In conclusion, what we eat is more important than how many calories we consume.   By adjusting what we eat rather than counting calories, we may be able to achieve more lasting weight loss and better health.


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