Look around you and chances are you’ll see that more than one adult in three are overweight or obese. Perhaps you are among them and you’re thinking, “That’s OK. I’m no different from anyone else, so what’s the point in waging yet another losing battle against the bulge?” You are not alone. A subtle form of peer pressure has convinced many, consciously or otherwise, that it’s acceptable to be significantly heavier than the “normal” weight ranges listed on a body mass index or doctor’s height-weight chart. As Americans have gained extra pounds in recent decades, Mary A. Burke, an economist with the Federal Reserve Bank of Boston who studies social norms, says they seem to have adjusted to a new normal regarding weight. A study she and co-authors published in 2010 revealed that a growing proportion of overweight adults — 21 percent of women and 46 percent of men (up from 14 percent and 41 percent in the 1990s) — consider their weight “about right.” And a study published in JAMA last year found that fewer adults who were overweight or obese were trying to shed excess pounds. Public-health experts fear that this trend toward “fat acceptance” bodes ill for well-being and the soaring costs of chronic weight-related ailments like heart disease, hypertension, Type 2 diabetes and more than a dozen kinds of cancer. As Burke wrote in a recent issue of JAMA devoted to obesity, public-health and medical professionals worry that “individuals who do not believe they are overweight, or who view obesity in a positive light, are less likely to seek treatment for weight loss.” Even doctors may be tempted to give up trying to convince their patients to lose weight. Although Medicare now covers up to 20 visits for weight-loss counseling each year, few doctors (or perhaps I should say few patients) have taken advantage of this benefit. Yet, only a 5-percent or 10-percent reduction in weight can often result in a significant improvement in health risks like high blood pressure, blood sugar or serum cholesterol levels. In other words, you don’t have to become model-thin to improve your health and life expectancy. In an editorial in the JAMA issue, Dr. Edward H. Livingston, a bariatric surgeon at the University of Texas Southwestern School of Medicine, suggested that perhaps a different message — one that encourages physical fitness — would do more to improve the health of the overall population “than continuing to advise weight loss when that message is increasingly ignored.” Indeed, as one team of specialists put it in JAMA, “Low cardiorespiratory fitness may pose a greater risk to health than obesity.” The team, headed by Ann Blair Kennedy, of the University of South Carolina School of Medicine, cited a 2014 analysis showing that, compared with normal-weight people who were physically fit, unfit individuals had an increased risk of death regardless of what they weighed, and those who were fit and overweight or obese did not face a significantly greater mortality risk when compared with normal-weight individuals. But, before you give up trying to lose weight, a better understanding of the likely sources of those extra pounds and the most successful approaches to losing them may help you achieve a double goal: more fitness and less fatness. The average weight of American adults and children was fairly stable until 1980. Then began a frightening rise that has only recently shown some signs of leveling off. There are many reasons, among them the growing employment of women outside the home contributing to a decline in home cooking; greater reliance on packaged and processed foods; the rise of fast foods, takeout and restaurant meals; and a commensurate decline in physical activity. A result: more calories in and fewer out, a perfect formula for weight gain. Several decades of commercial weight-loss diets, ranging from the Drinking Man’s Diet to the low-carb Atkins Diet, each claiming to be the best way to get rid of unwanted fat with minimal or no sacrifice to taste and satiety, tempted those struggling with rising poundage. Most, however, involved a radical change in people’s eating habits that was rarely sustainable. After a while, dieters returned to their old habits and regained the lost weight, often more than they had lost in the first place. As Livingston stated, “Providing patients with the false hope that if they only reduce one class of foods or another (e.g., carbohydrates or fats) they will lose weight can become frustrating, and may in part explain the failure of most diets.” Even reducing consumption of sugar-sweetened beverages (which provide no nutrients beyond sweet calories), he wrote, “is not likely to influence obesity at the population level,” which has continued to increase even as soda consumption has declined. Rather than a soda tax, Livingston endorsed taxes based on the calorie content of foods, and using the revenue generated “to subsidize healthy foods to make them more affordable.” Noting that “the common denominator for all successful diet plans is calorie reduction, irrespective of how that is achieved,” he said that a slimmer U.S. populace can be achieved only if attention is paid to the entire food supply. That attention is unlikely to be paid anytime soon by either the processed food industry or government regulatory agencies, so it is up to consumers to take matters into their own hands, eyes and mouths. The goal is not radical change, but a reduction in calories of 500 a day or an increase in physical activity — or both — to achieve a weekly deficit of 3,500 calories, the approximate amount in 1 pound of body fat. Just eliminating any of these — a bagel with cream cheese, one Big Mac, a Belgian waffle with a drizzle of syrup, one cup of Häagen-Dazs Green Tea ice cream, a Starbucks Venti Caramel Frappuccino with whipped cream, or one serving of a Cheesecake Factory Santa Fe chicken salad — will create that 500-calorie deficit. (For the sake of comparison, you’d have to eat six apples or seven eggs to get to 500 calories. Or you could choose a two-cup Wegman’s Caesar salad for a mere 200 calories.) If you live in a city that mandates calorie listings on menus, pay attention before you order. Also, always request dressings and sauces on the side and drizzle them on yourself rather than let the restaurant pour hundreds of calories on a low-calorie salad or chicken breast. Jane Brody is The New York Times health columnist.