FOUR out of five black women are seriously overweight. One out of four middle-aged black women has diabetes. With $174 billion a year spent on diabetes-related illness in America and obesity quickly overtaking smoking as a cause of cancer deaths, it is past time to try something new.

What we need is a body-culture revolution in black America. Why? Because too many experts who are involved in the discussion of obesity don’t understand something crucial about black women and fat: many black women are fat because we want to be.

The black poet Lucille Clifton’s 1987 poem “Homage to My Hips” begins with the boast, “These hips are big hips.” She establishes big black hips as something a woman would want to have and a man would desire. She wasn’t the first or the only one to reflect this community knowledge. Twenty years before, in 1967, Joe Tex, a black Texan, dominated the radio airwaves across black America with a song he wrote and recorded, “Skinny Legs and All.” One of his lines haunts me to this day: “some man, somewhere who’ll take you baby, skinny legs and all.” For me, it still seems almost an impossibility.

Chemically, in its ability to promote disease, black fat may be the same as white fat. Culturally it is not.

How many white girls in the ’60s grew up praying for fat thighs? I know I did. I asked God to give me big thighs like my dancing teacher, Diane. There was no way I wanted to look like Twiggy, the white model whose boy-like build was the dream of white girls. Not with Joe Tex ringing in my ears.

How many middle-aged white women fear their husbands will find them less attractive if their weight drops to less than 200 pounds? I have yet to meet one.

But I know many black women whose sane, handsome, successful husbands worry when their women start losing weight. My lawyer husband is one.

Another friend, a woman of color who is a tenured professor, told me that her husband, also a tenured professor and of color, begged her not to lose “the sugar down below” when she embarked on a weight-loss program.

And it’s not only aesthetics that make black fat different. It’s politics too. To get a quick introduction to the politics of black fat, I recommend Andrea Elizabeth Shaw’s provocative book “The Embodiment of Disobedience: Fat Black Women’s Unruly Political Bodies.” Ms. Shaw argues that the fat black woman’s body “functions as a site of resistance to both gendered and racialized oppression.” By contextualizing fatness within the African diaspora, she invites us to notice that the fat black woman can be a rounded opposite of the fit black slave, that the fatness of black women has often functioned as both explicit political statement and active political resistance.

When the biologist Daniel Lieberman suggested in a public lecture at Harvard this past February that exercise for everyone should be mandated by law, the audience applauded, the Harvard Gazette reported. A room full of thin affluent people applauding the idea of forcing fatties, many of whom are dark, poor and exhausted, to exercise appalls me. Government mandated exercise is a vicious concept. But I get where Mr. Lieberman is coming from. The cost of too many people getting too fat is too high.

I live in Nashville. There is an ongoing rivalry between Nashville and Memphis. In black Nashville, we like to think of ourselves as the squeaky-clean brown town best known for our colleges and churches. In contrast, black Memphis is known for its music and bars and churches. We often tease the city up the road by saying that in Nashville we have a church on every corner and in Memphis they have a church and a liquor store on every corner. Only now the saying goes, there’s a church, a liquor store and a dialysis center on every corner in black Memphis.

The billions that we are spending to treat diabetes is money that we don’t have for education reform or retirement benefits, and what’s worse, it’s estimated that the total cost of America’s obesity epidemic could reach almost $1 trillion by 2030 if we keep on doing what we have been doing.

WE have to change. Black women especially. According to the Centers for Disease Control and Prevention, blacks have 51 percent higher obesity rates than whites do. We’ve got to do better. I’ve weighed more than 200 pounds. Now I weigh less. It will always be a battle.

My goal is to be the last fat black woman in my family. For me that has meant swirling exercise into my family culture, of my own free will and volition. I have my own personal program: walk eight miles a week, sleep eight hours a night and drink eight glasses of water a day.

I call on every black woman for whom it is appropriate to commit to getting under 200 pounds or to losing the 10 percent of our body weight that often results in a 50 percent reduction in diabetes risk. Sleeping better may be key, as recent research suggests that lack of sleep is a little-acknowledged culprit in obesity. But it is not just sleep, exercise and healthy foods we need to solve this problem — we also need wisdom.

I expect obesity will be like alcoholism. People who know the problem intimately find their way out, then lead a few others. The few become millions.

Down here, that movement has begun. I hold Zumba classes in my dining room, have a treadmill in my kitchen and have organized yoga classes for women up to 300 pounds. And I’ve got a weighted exercise Hula-Hoop I call the black Cadillac. Our go-to family dinner is sliced cucumbers, salsa, spinach and scrambled egg whites with onions. Our go-to snack is peanut butter — no added sugar or salt — on a spoon. My quick breakfast is a roasted sweet potato, no butter, or Greek yogurt with six almonds.

That’s soul food, Nashville 2012.

I may never get small doing all of this. But I have made it much harder for the next generation, including my 24-year-old daughter, to get large.

Alice Randall is a writer in residence at Vanderbilt University and the author of “Ada’s Rules.”