Is fate making you fat?

If you're worried about your weight — and who isn't? — you may have the feeling lately that science is really jerking you around.

Consider recent findings: Rats fed saccharin gain weight faster than rats fed sugar. Some overweight humans live longer than skinny ones. Diabetics who drive down their blood sugar to "normal" levels are more likely to die of heart disease.

Even the result of "just eat less and exercise more" is under scrutiny, as researchers find that some obese people are destined by their genes and metabolism to stay fat.

Maybe it's time to be realistic and play the cards we're dealt.

"The reality is that people have less control over their weight than they realize," said Gina Kolata, whose book "Rethinking Thin" looks at the science of weight loss. "Weight is inherited almost as strongly as height. No matter how much you'd like to be skinny, you may not be able to be as thin as you would like."

Kolata suggests that Americans should stop blaming people for obesity.

"It's just as hard for a thin person to gain 100 pounds as it is for an obese person to lose it — or even 50 pounds, or even, I hate to say it, 20 pounds," she said. "It's not that easy to change your weight just because you will yourself to."

The hardest part

Hard as dieting is, losing weight is easier than keeping it off.

Even Oprah Winfrey, one of America's wealthiest women, with personal trainers and chefs, struggles with gaining and losing repeatedly, points out University of California-Davis nutrition professor Judith Stern.

"It's really hard to keep weight off," Stern said. "Some of it has to be biology. Some of it has to be the environment."

And some of it is probably interactions between the two that we don't fully understand.

Just as with diet sodas, artificial sweeteners and other food controversies, Stern said, "when all the evidence is in, the patients will be dead. We don't have all the information right now."

Tips to try

In the absence of firm knowledge, she advised people to try out different strategies that do have some support in medical literature, and see which approaches might suit them.

Among things you might try:

Drink unsweetened tea, especially oolong, which has a long tradition of use for weight control in Japan.

Before dinner, have a bowl of soup, not just broth but something with vegetables.

If you're prone to mindless eating at a desk or elsewhere, keep healthy snacks around.

No matter what you settle on, Stern said, "Know who you are. Know what compromises you're willing to make. Know what you're not willing to do."

Stern is such a dessert fan that if a restaurant has one of her favorites, she will sometimes order it first, relish it completely, and then order the rest of her meal, perhaps just a salad or appetizer. She knows she'll order the dessert no matter what, so she may eat less overall by eating dessert first.

The drastic alternative

Good tips — but tips weren't enough to help Lodi, Calif., truck driver Mike Williams. Faced with intractable obesity, he eventually tried something more drastic.

"Diets work, but I don't think they last," said Williams, 54, who says he has fluctuated by 50 to 70 pounds at least five times.

At 5 feet, 4 inches tall, Williams zoomed up from his high-school weight of 145 to more than 200, then more than 250, 260 and even 270. He lost on Weight Watchers, NutriSystem, the Atkins diet and even a soup diet, but for nearly 30 years, he regained every time.

Finally, after even his post-heart-attack weight loss failed to stick, Williams opted for gastric bypass surgery.

Today his scale reads 190.

Aim low!

For those looking for a solution less invasive than surgery, another strategy is to set modest, more personalized goals. Liz Applegate, an expert on diet and fitness at University of California at Davis, advised setting an initial target of dropping 5 or 10 pounds.

"When you've achieved that, you'll have a sense of accomplishment," she said. "Be realistic — don't announce that you're going to lose 50 pounds or weigh what you weighed in junior high."

She said long-term studies of people who have managed to maintain weight losses show similar patterns: They don't skip meals, particularly breakfast. They don't fool themselves about how much they're eating. They find ways to exercise during the day for a total of 60 to 90 minutes.

And they are vigilant about not letting pounds creep back: "They have a monitoring device that works for them: A scale. A notch on a belt. A skinny pair of jeans."

Applegate's mantra is that it can be done — and Kolata agrees, up to a point.

"I don't want to say it's useless, that you can't lose any weight, because people can and do," she said. "But it's very hard not to get caught up in this zeal that people think they can weigh anything they wanted to if they just will it. It's like saying, 'I could grow a few inches if I just really wanted to.' "