Want to live a long life? Get married. Study after study has shown that married people, particularly married men, live significantly longer than their single friends.
Doctors at Harvard tossed some more data on the pile last month, showing that married patients were more likely to identify cancer in its early stages and less likely to die from the disease than their unmarried peers.
Epidemiologists refer to the correlation as the “marriage protection hypothesis,” and it’s not entirely surprising. Having a family gives people something to live for, which may discourage risky behaviors like smoking and riding a motorcycle. Married men commit suicide at lower rates than singles, possibly for the same reason.
Your spouse may urge you to get a mammogram, wear sunscreen or have that worrisome mole checked out. A life partner provides an outlet to discuss personal stresses. Married people may remain more intellectually engaged with others, which helps avoid dementia.
It’s not all good news for married people, though: Marriage also increases obesity rates. Getting married raises the risk of a woman becoming overweight by 3.9 percentage points compared to peers who did not marry, and increases her risk of obesity by 1.4 percentage points. The effect is more pronounced for men. Married men see a 6.1 percentage point rise in the risk of becoming overweight and a 3.3 percentage point increase in the risk of obesity.
Obesity can be caused by the cumulative effect of years of eating just a little more than we should. While less than 33 percent of us are obese between the ages of 20 and 39, nearly 40 percent of Americans older than 60 are obese. It’s a bit of a paradox that marriage is connected to both longevity and obesity, one of the primary contributors to early death.
The nature of the connection between marriage and weight gain is a matter of conjecture. One plausible explanation is the “marriage market hypothesis”: Single people remain thin for no other reason than to attract a mate. But that theory flies in the face of the overall marriage protection hypothesis. If people quit smoking, wear sunscreen and eschew suicide for the sake of their families, why would they allow themselves to become obese?
There may be a simple explanation: People eat more when they’re together. A 1992 study that asked participants to record their food consumption for a week found that eating with one companion increased meal size by 41 percent compared with eating alone, while breaking bread with six or more people increased an individual’s caloric intake by a whopping 76 percent. Other studies have found somewhat more modest increases, but the effect is remarkably consistent.
Why do we eat more when we eat with others? It may be a result of social norms. Communal meals tend to last longer than eating solo, and people who sit in front of food can’t resist eating it.
Another possible explanation is our habit of mimicking our dining companions: When they take a bite, we take a bite. The habit may, alternatively, lie deep in evolutionary history. Chimpanzees and marmosets spontaneously share food, probably to help form social bonds.
From the innocent, altruistic act grew a regrettable human custom. Perhaps you feed (and feed, and feed) your spouse to strengthen your marital bond, even if you’re ultimately shortening its duration.