I spent a week in Chicago and gained four pounds. This wasn't unexpected: A great deal of what Christmas is about these days is sugar, and Christmas is one of the very few times of the year when I let my sugar guard down. Cookies, candy, and egg nog were all over the place, and I indulged. Fortunately, I know how to lose that weight again: Eat animal fat. So it's back to my accustomed diet, which depends heavily on meat, eggs, and full-fat dairy, plus whatever vegetables I can choke down against my gag reflex. I also eat one slice of Orowheat Master's Best Winter Wheat Bread per day for fiber, and a few Wheat Thins here and there for carb balance. Desserts are off the table for awhile.
If I can resist the temptation to indulge in potato chips (we don't keep sweet stuff in the house, as a rule) I'll be back in range (150-155) in about ten days. Better still, I'll stay there, probably until next Christmas.
Our visceral fear of eating fat would be funny if it weren't so tragic. Researchers have begun to admit that low-carb diets are best for keeping weight off, but are still terrified of admitting that animal fat is not only harmless but medically necessary. Best illustration: the wonderfully named mal de caribou, also known as "rabbit starvation."
Mal de caribou (literally, "caribou sickness") typically afflicts explorers and other cold-weather adventurers who attempt to live on hunted animals but only eat the muscle tissue. Rabbits (and most wild animals, actually) have very little body fat. (I have to brown the local ground buffalo meat in butter or it would burn. There's basically not a shred of fat in it.) If all you can score out in the wild are rabbits, plus the occasional deer, you run the danger of severe vitamin deficiencies, plus liver dysfunction caused by an overload of protein. Eating carbs helps short-term, but as studies of aboriginal peoples deprived of their natural diets have shown (see Taubes for all the citations you could ever digest) replacing fat with carbs over the long haul leads to obesity, diabetes, and various other degenerative conditions. Farley Mowat has much to say about this in his book People of the Deer; a good summary can be found here. The original diet of most northern aboriginal peoples consisted of meat and fat. Grains and sugar were basically absent.
I'll have to come back to the issue of whether or not total caloric input matters, and how much--the research there is divided and contentious--but I will freely admit that I eat less than most people do. The key is that eating fat keeps me from getting hungry, so I'm less tempted to binge on starches. Maybe it won't work that way for you, but granting that we're all different biochemically (to the extent that I wonder sometimes if we're all one species!) there seems to be a trend in this direction. Dump the Honey Bunches of Oats and fry an egg in butter for a month instead and see what happens. You may be surprised.