2.3: Why Do We Become Overfat?

The public has a wide variety of ideas about how to cure obesity, but it appears to share one basic idea about its cause—gluttony. Anthropologist Margaret Mead said: “As the obese often describe themselves (echoing the beliefs and attitudes of those around them), they are people who can’t resist indulging their gluttonous greed.”³

The idea is worth testing. Many of us are already eating somewhat less than we’d like, and avoiding a number of foods in the belief—often mistaken—that they “make us fat.” This, of course, is especially true for those of us who are already a little fatter than we’d like to be. Thus, it can seem that maintaining our weight—let alone reducing it—means resigning ourselves to a life of eating without joy.

Such a depressing point of view can discourage people from even attempting to deal with what’s a very real problem. Just facing a need for weight control can evoke deep feelings of shame and guilt, in addition to the prospect of unending self-sacrifice.

But how true is the idea that gluttony is the central cause of obesity? When the nutrition scientist applies the facts of energy to the question, it’s found that gluttony isn’t a requisite for overweight. Only small differences in our intake and use of energy can make great differences in fat storage. From this analysis, we can learn much about how to manage our fatness.

An Analysis of Fat Storage

Often our attention is focused on a few sporadic episodes of extravagant over-eating—which can lead to guilt, despair, and a feeling of helplessness. Let’s imagine a very limited sort of glutton, a man who—in addition to the food energy he needed each day—ate an extra ounce of choice porterhouse steak. Very roughly, this amounts to about 125 calories a day.

Using our energy data, we divide these calories into the 3,500 which approximate a pound of body fat and find that every 28 days, this man would gain a pound, assuming all else (e.g., his physical activities) remain the same. In a year, he’d gain 13 pounds.

If we start him on this pattern at age 20 when he weighs 180 pounds, by the time he’s 40 he will have gained some 260 pounds and will weigh 440 pounds. You have only to think of how many people you know who weigh 440 pounds, and you will see how few people are gluttonous even to the extent of an extra ounce of steak a day.

In reality, our 180-pound young man might weigh between 200-220 pounds at age 40—and think of himself as fat. If we put our equations into reverse, we can find how much extra daily food he would have eaten on the average: He would have gained one or two pounds a year during 20 years. That averages out to an excess of less than 10-20 calories a day. For a smaller person, say a 128-pound woman who gets a little pudgy, the excess would be even less.

Table 2-2: Small changes in diet can lead to big changes in weight IF we don’t eat more of other foods to compensate!

Current Diet	Change to	Calories Saved	How Often	Loss/Year
1 cup whole milk (150 cal)	1 cup 1% fat milk (105 cal)	45 cal	2x/day	9 lbs.
20 potato chips (210 cal)	20 pretzel sticks (40 cal)	170 cal	2x/week	5 lbs.
12-oz. can cola (150 cal)	12-oz. can diet cola (2 cal)	148 cal	3x/week	7 lbs.
1 cup granola (515 cal)	1 cup 40% bran flakes 160 cal)	355 cal	3x/week	16 lbs.

To measure the caloric value of one’s diet to an accuracy of 10-20 calories a day is virtually impossible even in the laboratory.

Of course, in practical terms our food intake varies from day to day. Chances are that any excesses are sporadic. We sometimes overeat extravagantly and sometimes, even, undereat. But we remember the excesses and tend to overlook the small daily habits that are usually the real culprits. Occasional episodes of gluttony are relatively unimportant in terms of our overall caloric balance.

Most of us don’t have the time or patience to try to keep track of our “overeating” by counting every calorie we eat. Remember, also, that the neat food tables of caloric values are averages. The same food will vary in calories and composition according to the variety grown, the soil, the climate, fertilization, the amount of sun, and many other factors. For example, changes in climate cause changes in the sugar content of grapes, which is one of the reasons why wines differ in different vintage years.

Careful as we may be, how accurately can most of us guess the exact size of a mound of mashed potatoes on our plate? How about the weight of a steak within an ounce? And remember what a difference an ounce of steak can supposedly make.

There are also individual differences in how our bodies use food and energy. After all, even two cars of the same make and model can use fuel at different rates. Not only are we a good deal more subtle and complex than automobiles, but each of us is a unique model from different manufacturers.

Not all of the differences are yet fully understood. But there’s far more knowledge than most people suspect about how fat we are, how we got that way, how lean we should be, and what we can do to change ourselves. For while few of us are gluttons, many of us are losing some of our potential for health to our own fat-storage cells.

The Genetic Factor

Fatness has a strong hereditary component. To measure the importance of this effect, consider your odds of becoming fat. If neither of your parents is obese, your risk of obesity may be less than 10%. With one obese parent, the risk of fatness rises to about 40%. If both parents are obese, your chance of becoming so is about 80%.⁴

At one time, this familial pattern was largely attributed to the eating habits of obese parents, which supposedly determined the food choices of their children. To an extent, this probably has some reality. A child who’s taught to savor fatty foods may favor them in adulthood. Meat, for example, simply may not taste right without gravy. Potatoes may not seem good without lots of butter.

Today, the eating habits taught by parents are thought to have more of an impact in terms of the ways in which food is used. For example, the habit of eating everything on one’s plate—like it or not, want it or not—can be more destructive of energy balance than what’s on the plate. Then there’s the effect of accustoming a child to use food as a way of dealing with stresses. (“There, there, have a cookie and you’ll feel better.”)

Learned personality patterns can also lead to using foods to deal with stress. This may cause a person to engage in episodes of overeating as stress increases.

Aside from such factors, studies have shown some clear genetic bases for obesity. For example, identical twins brought up separately, in different environments with different adult models, have shown a remarkable tendency toward similar fatness or thinness.⁵

In one study, 12 pairs of identical twin brothers monitored in a dormitory with restricted physical activity were fed an excess of 1000 calories per day for 4 months. The 12 sets of twins differed a lot in how much weight, body fat, and lean mass they put on, but each set of twins (the two brothers) responded similarly.⁶ What causes this similarity?

Differences in Body Type

One genetic factor is our inherited body type. The shape, and to some extent the composition of our bodies can be as predetermined as the color of our hair, the family nose, or the family chin. Body shapes are generally assigned to one of three categories (see Fig. 2-5); but most of us are a blend of all three, with a preponderance toward one or two of them.

Figure 2-5: Body Types

Ectomorphs are slight of frame—reed-like when seen in profile. They typically have long thin hands and feet, narrow and tapering fingers, a tendency to develop wiry or stringy muscle, and a low fat-storage capacity.

Endomorphs appear almost as an opposite—softly rounded in style, often with narrow and sloping shoulders, and a torso which bulks toward the abdomen and hips, suggesting a sort of pear shape. The hands and feet are likely to be pudgy and short and, like the fingers, rather flame-shaped. Their muscles tend to be soft and not well defined, and there’s a lot more fat-storage capacity.

Mesomorphs are sometimes described as between the other two types, but this isn’t really accurate. They are the football types—broad shoulders, deep chests, with heavy bones and sturdy legs. Their hands are likely to be squarish, with blunt-shaped fingers, and they have bunched, well-formed muscles. Their fat-storage is greater than the ectomorph, but less (and more evenly distributed) than that of the endomorph.

While pure body types are unusual, there’s a tendency to speak of people according to predominant type or types, such as “endomorphic” or as “a meso-endomorph.” It’s probably obvious that there’s a relationship between inherited body type and capacity for fat-storage.

Body Shape and Composition

The composition and shape of our body affects our energy needs and the tendency to become overfat. For example, the energy needed to keep our body functioning at its most basic level (basal metabolism) is between 10 and 20% higher for men than for women. One reason is that men generally have more muscle and less fat than women, by about 10-20%. Some of this may be due to muscle development, but some is definitely a sexual characteristic.

Lean tissue uses more energy than fat tissue. So leaner people of either sex have a higher basal requirement. Suppose we have two men who weigh about 150 pounds. One is thin, and the other is a bit plump. At rest, the thin man burns about 1.26 calories per minute, and the plump man 1.16 calories.

The difference, a tenth of a calorie per minute, doesn’t sound like much. But if both men eat the same amount of food, the plump man treats that tenth-of-a-calorie difference as an excess and stores it. That’s 6 calories per hour, or 144 extra calories a day, which theoretically could add a pound every 24 days.

---

Normal % body fat is about 10% for young men and about 20% for young women.

---

Thus, an inheritance of muscularity can mean an ability to accommodate greater caloric intake without getting fat. But heredity goes further; the shape of the body helps to determine the total body surface. A long, thin person will have much more body surface than a short, plump person of the same weight. Since the greater the body surface, the greater the heat loss, a tall, thin body shape means a higher basal metabolism. It can also influence how many calories of energy are used up during activity.

We can see a vicious circle emerging. The thin and lean have more muscle relative to fat, have more body surface, and burn more calories at an idling speed than a stockier or fatter person of the same weight. In this way, nature tends to exaggerate the problems of the heavy and perpetuate them. There can be some reality to the complaint of the stocky man married to the slight woman who says, “She eats like a horse and doesn’t gain an ounce; I starve myself and get fat.” More often, because of the inherently greater fatness of women, the complaint is the reverse, with women burning less energy for each pound of body weight.