What We Don’t Know for Sure Famine Sensitivity
Is obesity inherited? You may believe it is, based on the prevalence of overweight people in your family, or a neighbor’s family. A relationship appears rather obvious because overweight parents have kids who are or become overweight more often than not. And research bears this out.
When an overweight person says she’s “got her mother’s body,” she is telling the truth from a certain perspective. But when she says this, she probably doesn’t really understand why this is true—what role heredity actually plays. People do not inherit obesity per se. But they do inherit a predisposing factor that makes it more likely that they will grow heavier by the year. Famine sensitivity plays a definite role in the feast or famine cycle. As we saw in Chapter 2, this factor influences the degree to which a body responds to a famine.
Obesity researchers Stephen O’Rahilly and I. Sadaf Farooqi said, “Hereditary influences on adiposity are profound and continuing.”
In another study, T.T. Foch and C.W. Mclaren stated, “Obesity appears to be highly heritable, as determined by studies of twins and adoptees. If neither parent is obese, the likelihood of the child’s becoming obese is only 8%. If one parent is obese, the likelihood jumps to 40%, and if both parents are overweight, the probability of the child’s becoming obese is an astonishing 80%.” These are statistics from obesity research, and they are frightening. Are kids from overweight parents just doomed to become fat and stay that way, no matter what they do?
Stomach Weight Loss Tips Photo Gallery
A Predisposition is Not a Cause
As we discussed in the last chapter, all human beings come into the world with various adaptive potentials—unique abilities to adjust to environmental stresses. We have been talking about the stress of inadequate food and this stress affects different people to different degrees. The degree to which a body reacts to the lack of food—famine sensitivity—is inherited. For some bodies, a restricted food intake doesn’t affect them much, and they tolerate it well without serious changes in hunger, eating or metabolic rate. But, some bodies are at the other end of the scale. They react strongly to food deprivation with slowed metabolism and increased appetite with cravings. Bodies that react least have low famine sensitivity and bodies that react strongly to going hungry have high famine sensitivity. Most bodies are probably somewhere on a scale between these extremes, but it is likely that most human beings fall above the midpoint—with higher than average famine sensitivity. This is because of the important role that famine sensitivity has played in keeping humans alive for eons.
The Whole Equation
Famine sensitivity by itself does not make anybody fat. But, famine sensitivity plus regular famines does. People with low famine sensitivity seem to be able to eat whatever they want, whenever they want. They normally don’t binge or overeat as a result of missing a meal. They just fit eating into their lives when it’s convenient. The erratic food supply of our modern environment doesn’t cause them to gain weight, at least while they are young, because their bodies tolerate these famines so well. They just stay thin. But in a real serious famine, they may be at a higher risk for starvation.
Those with high famine sensitivity—a predisposition to gaining weight easily when intermittent under eating occurs—usually start gaining as a result of some type of restricted eating in their lives. This typically happens in grade school or high school. School schedules interfere with kids’ ability to eat when they get hungry, and they have the type of bodies that adapt quickly to this stress. When they finally eat afer going hungry for too long, they tend to overeat to make up for the famine. Their metabolisms get sluggish, they crave junk foods and they may start to binge.
You can determine your famine sensitivity just by looking at your own weight and diet history and then your close relatives: parents, siblings, aunts and uncles.
There is one more trait that makes a person more vulnerable to obesity. It is a special ability to tolerate going hungry. For some people, going hungry is not particularly uncomfortable. They don’t have strong urges to seek food when they get hungry and can put off eating for long periods of time. Famines are easy for them Unlike famine sensitivity, this trait is probably acquired as a result of erratic eating habits.