Year: 2004

A reader writes:

One thing I remember seeing in the news is that children in the US are much more overweight than in past generations.

Actually, the problem is much worse than children. The whole US population is much more overweight than in past generations. According to current statistics, two thirds of the American population is overweight (having a Body Mass Index [BMI] of 25 or more) and one third of the population is obese (having a BMI of 30 or more). This means that only a third of the population has a healthy weight by BMI reckoning [Source]. Now, there are some problems with the BMI scale (it doesn’t take into account muscular people or people who have suffered muscle loss), but it provides enough of a benchmark to show that there is a huge problem. Further, the problem is getting worse, and the trend toward obesity has been dramatically accellerating in recent years.

If your explanation of weight gain is true, and it may very well be, how does one also explain the much greater incidence of obesity among children (as well as adults) than in past generations? If the problem of obesity is primary biological, why would we see such a large increase in the percentage of obesity in today’s generations?

Actually, I haven’t thus far commented on why people gain weight. I’ve merely pointed out that the body tries to maintain a particular weight level homeostatically, which is why people find significant weight loss so difficult: Your body fights you as you start trying to lose. Under most diet strategies, the body will simply up your hunger level and give you cravings to get you to make up the calories that you are trying to avoid by following your diet program. How a person got to being overweight is a different question.

As far as why our generation is so much more overweight than prior ones, there are three basic reasons:

• The first reason is that we exercise less than former generations did. A hundred years ago, most people worked outdoors, which meant much more physical activity than we office-dwellers get today.
• The second reason is that we take in more calories per day than prior generations
• The third reason has to do with your question concerning the nature of the food we eat:

Perhaps it is not only a function of how many calories one eats, but also what kinds of calories one eats. Does a person gain more weight from eating 500 calories worth of donuts than they would from eating 500 calories worth of fruit, for example?

The form of the calories don’t matter that much in and of themselves. A thousand calories of protein or fat or carbohydrates is still a thousand calories. But the type of calories does have an effect on the body’s metabolism because the body has to do different things in order to burn different macro-nutrients (i.e., protein, fat, and carbohydrates). If you change the ratio of the macro-nutrients you are eating, your body’s metabolism changes in order to digest and/or store them.

And that’s where part of the problem comes in: One of the macro-nutrients–carbohydrates–triggers an insulin response in the body that can send your blood sugar skyrocketing (which is why diabetics have to regulate their carbohydrate intake and often need to take insulin to help control their blood sugar). But blood sugar will quickly fall again, and when that happens your body starts to get weak (which is why people get sleepy in the hour after lunch), and your body triggers a new hunger response in order to get you to eat more and thus raise the blood sugar level back to where it was (which is why you get hungry an hour after eating carbyhodrate-rich Asian food). The result is that eating too many carbohydrates puts you on a blood sugar roller-coaster that keeps leaving you weak and hungry, and when you eat to get your blood sugar back up, you take in more calories.

Now, guess what the big change has been in the last hundred years in our diets? That’s right: We take in way more carbohydrates, particularly refined carbohydrates that will make your blood sugar go nuts. Wherever this high-calorie, high-carb, high-refined carb “Western diet” gets introduced in the world, the problems of overweight, diabetes, and heart disease quickly follow. It’s simply not what our species is meant to eat. We’re hunter-gatherers by nature, and hunter-gatherers have a diet rich in protein and fat but not carbs, and especially not refined carbs.

Now, why has the weight problem been accellerating in America? Here’s part of the reason:

I’m sure you recognize the famous “Food Pyramid” or, as I prefer to call it, the “PYRAMID OF EVIL.” Like everbody else, I assumed when the pyramid first came out that it represented the diet you were supposed to eat to be healthy, but back then I hadn’t studied diet and nutrition. After my weight situation forced me to do so, I came back, looked at the pyramid again, and was shocked. “Man! This is the Give-Your-Children-Diabetes Pyramid!” I exclaimed.

The recommendations it makes are absolutely insane. It’s way out of whack with what our species is designed to eat. Six to eleven servings of grain a day is completely crazy for a hunter-gatherer species. The additional two to four servings of fruit only makes the problem worse.

People have the idea that fruit is a healthy food that ought to be eaten in large quantities, but this falls apart when one applies a little common sense. Ask yourself: What is the one foodstuff that everybody (hi-carb dieters, lo-carb dieters, the Food Pyramid, everbody) agrees needs to be eaten in very limited quantities? Sugar. Now, what is it that makes up prefer to eat fruit over vegetables? Sugar. Fruit has lots of sugar in it. In fact, that’s the main difference between a fruit and a vegetable: What we call a fruit has more sugar than what we call a vegetable. Biologically, they tend to perform the same function (they both tend to be the seed-bearing parts of a plant). One simply tastes better to us because it has more sugar in it, and so we have a different word for it.

If you compare the amount of sugar and other carbohydrates in fruits to the amount in manmade confections, the differences are not that great. They can even stand your expectations on their head. A typical 8″ banana that you’d buy in a store has 31 grams of carbohydrates in it. By contrast, a Hostess powdered sugar donut has only 19 grams of carbs. There are some advantages of fruit over pastry, but not near as much as people have been led to believe. About the best that I can say for most fruits is that they are less unhealthy as a major component of your diet (though, as with anything, in limited quantities they’re fine).

Now, here’s something you probably didn’t know about the Food Pyramid: Know which government agency puts it out? You’d think that it would be one of the ones that monitors public health, like the Food and Drug Administration or the National Institutes of Health or even the Center for Disease Control, right? Wrong. It’s a creature of the United States Department of Agriculture–the body tasked with monitoring and (in practice) looking after the interests of the farm industry.

The Food Pyramid is a marketing ploy designed to get people to eat the foods that the farm industry wants them to eat.

Why does the farm industry want people to eat certain foods? Look at the ones at the base of the food pyramid and compare them to those at the top. Except for the “use sparingly” category, the foods at the top almost all (a) come from animals and (b) require refrigeration. The ones at the bottom almost all (a) come from plants and (b) don’t require refrigeration. The significance of those facts is that the ones at the bottom of the pyramid are all low-cost to manufacture (plants don’t require as much investment to raise as animals) and high-profit items (because the cost of the end product doesn’t have things like refrigeration coming out of its profit margin).

Getting people to eat low-cost, high-profit foods may serve the interests of agribusiness, but those aren’t the foods our species was designed to rely upon, and making them the principal components of our diet is bound to lead to problems–like overweight, diabetes, and heart disease.

A reader writes:

I agree that just because someone is overweight doesn’t necessarily mean they eat to much…however it does mean they don’t exercise

I’m sure that you probably don’t mean this to be taken as a technical statement, but . . . it’s . . . not . . . true. It comes across as a diss to people who are overweight. It sounds like a cavalier dismissal of their situation, including whatever efforts at exercise they may be making. It would be better to make the statement in a more qualified manner, for as it stands it is subject to a number of criticisms:

1) Exercise is not a binary phenomena. People don’t fall into two classes of “those who exercise” and “those who don’t exercise” with no further relevant distinctions. Physical activity is something that exists on a continuum, and merely falling into the “does exercise” category is not a guaranteed cure for the problem of overweight.

2) Even falling into the category of “does a lot of exercise” isn’t a guarantee of losing body fat. Look at professional football players. Those guys tend to get a lot of exercise, but they also tend to have a lot of body fat (because they consume more calories in order to simultaneously [a] keeping doing the exercise and [b] keep their bodies at the homeostatic weight points they want to remain at).

3) Depending on the metabolic state one is in, doing exercise can increase the appetite one has, as the body tries to stay at its homeostatic weight point and responds by increasing appetite as physical activity increases. If you just add some exercise without addressing dietary considerations, this is likely what will happen to you: You’ll just eat more. (Paradoxically, there are also states–which dieters can exploit–where the body decreases appetite as exercise increases. The point is simply that not everyone who exercises is going to lose weight.)

4) Even when one is in high weight loss mode, exercise is rarely if ever a sufficient condition for that weight loss. Exercise tends not to add that much to the calories we burn each day. Consider:

A 6’0″, 200 lb., 30 year old man is likely to have a Basal Metabolic Rate (BMR) of 2019 calories per day (BMR Calculator). This is the number of calories he needs just to lay in bed, without adding any physical activity. If you add his daily work duties to this (let’s say he does office work), you might get the number up to 2500 calories.

Let’s just stick with his BMR for the moment, though. How much physical activity would he need in order for exercise to equal what he needs to just keep the lights on and the machinery working? Well, he’d need to generate another 2019 of calorie burning through exercise. How much is that? It depends on the exercise he does, but let’s take a common one that is easily within the reach of almost all dieters: walking. If a person of his weight walks briskly for half an hour, he will burn approximately 220 calories. This means that in order for his exercise-based calories to equal his BMR-based calories, he would have to walk briskly for 4.6 hours a day. (NOTE: There are some quibbles to make with these numbers, but they don’t affect the scale of exercise required, so we can stick with these numbers for purposes of showing the principle.)

Very few people are able to make that kind of exercise investment, and so exercise rarely plays as big a role in calorie expenditure as BMR. The result is that diet rather than exercise tends to be the most important factor in weight loss. In order to effectively lose weight, dietary change is what is needed. Exercise is an important adjunct to this (otherwise I wouldn’t do five miles of aerobic power walking per day, plus weight training), but exercise by itself is not the solution to weight problems for most people. It’s not even the major factor. Diet is more important.

6) Exercise also is not a necessary condition for weight loss. A few years ago I was dealing with a significant weight problem and lost almost seventy pounds without doing any exercise, simply by making a dietary change.

Diet rather than exercise tends to be the dominant factor in weight loss. The trick is, how to take in less calories than you expend without being eaten alive by hunger–a subject I imagine we’ll end up discussing in the fullness of time.