Obesity Myths May Undermine Weight Loss Attempts

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Overweight and obese women -- defined as having a BMI (body mass index) over 25 -- have a higher risk of being diagnosed with breast cancer compared to women who maintain a healthy weight, especially after menopause. Being overweight also can increase the risk of the breast cancer coming back (recurrence) in women who have had the disease.

This higher risk is because fat cells make estrogen; extra fat cells mean more estrogen in the body and estrogen can make hormone-receptor-positive breast cancers develop and grow.

A study has found seven myths related to obesity and weight loss – beliefs that are unsupported by scientific evidence – are commonly mentioned in scientific papers and popular media, and that these myths may be undermining people’s attempts to lose weight.

The research was published in the Jan. 31, 2013 issue of the New England Journal of Medicine. Read the abstract of “Myths, Presumptions, and Facts about Obesity.”

The seven myths.

Small changes in energy intake or output that are maintained over time will produce large, long-term weight changes. This myth is based on the idea that it takes either an increase or decrease of 3,500 kilocalories (a kilocalorie is 1,000 calories) to cause a 1 pound weight increase or weight loss. Recent studies have shown that this isn’t true. So a person who expends 100 more kilocalories per day by walking a mile won’t lose more than 50 pounds over 5 years as the myth would have us believe. Instead, a person who begins walking a mile per day is likely to lose about 10 pounds over 5 years, assuming the person eats the same amount of calories per day.

Setting realistic goals for weight loss is important to avoid frustration. Although this sounds smart and reasonable, no studies have shown this idea works. In fact, several recent studies have shown that setting more aggressive weight loss goals can produce better weight loss results.

Slow, gradual weight loss offers better long-term results than rapid weight loss. Again, this sounds sensible, but studies have shown that faster and greater weight loss at the beginning of a program is associated with lower weight at the end of long-term follow-up.

People need to be ready to lose weight. Research has shown that a person’s “readiness” to lose weight doesn’t predict how well he or she will stick to a weight loss plan and it also doesn’t predict how much weight a person will lose. In five studies looking at more than 3,900 people whose readiness to lose weight was considered good, the average weight loss was less than 2 pounds at the end of 9 months.

Physical education classes are important to prevent or reduce childhood obesity. Another sensible sounding myth. Still, studies have shown inconsistent weight loss results when children went to more physical education classes per week. The researchers said that while there is almost certainly a combination of physical activity frequency, intensity, and duration that would work to reduce or prevent childhood obesity, it’s not clear if that level can be implemented in schools.

Breast-feeding protects against obesity. This myth is very popular, but randomized studies have shown no evidence that breast-feeding affects obesity. Still, it’s important to know that breast-feeding has other important benefits for mothers and children, including reducing the risk of allergies, asthma, and other illnesses.

Sex burns 100 to 300 kilocalories for each person involved. Without repeating all the math formulas the researchers used, we can tell you that sex burns about the same amount of calories as walking at a moderate pace (about 2.5 miles per hour). According to the study, the average bout of sexual activity lasts for about 6 minutes, so an average person might burn about 14 kilocalories during sex.

The researchers also discussed six presumptions about obesity that may also undermine weight loss, as well as nine facts and how they may be used to help people lose weight.

The six presumptions.

Regularly eating breakfast instead of skipping that meal protects against obesity. Randomized trials have found eating or skipping breakfast has no effect on weight.

Early childhood is when people learn exercise and eating habits that influence weight throughout life. No studies have proved this association true or false.

Eating more fruits and vegetables will cause weight loss (or less weight gain), even if you don’t exercise or adopt any other behavioral changes. While nutrient-dense fruits and vegetables offer health benefits, studies have shown that people who eat more produce can gain weight if they don’t make any other behavioral changes, such as exercising and eliminating processed sugar from their diets.

Yo-yo dieting (called “weight cycling” by doctors) is associated with a higher risk of dying. No one has studied this in people and the association hasn’t been proven in animal studies. It’s likely this presumption exists because people who yo-yo diet may have other health problems that increase their risk of dying.

Snacking contributes to weight gain and obesity. Randomized studies haven’t proven this.

The availability of parks and sidewalks affects the rate of obesity. No one has done a randomized study on an association between the risk of obesity and environmental components that encourage physical activity, such as parks, sidewalks, jogging trails, etc. Any study looking at the relationship between obesity and the built environment (as scientists call it) has been observational, which means that the researchers just observed people’s behavior and outcomes – no treatment or intervention was given. Observational studies are not as good as randomized studies. Also, these observational studies have offered mixed results, so there are no clear conclusions.

The nine facts.

While your genetics play a large role in your weight, they are not your destiny. Making changes in what you eat and how often and how intensely you exercise can help you lose weight as well as any weight-loss drug.

Dieting can help you shed pounds in the short term, but isn’t sustainable over time. While dramatically slashing the number of calories you eat may help you drop several pounds in just a couple weeks, chances are you’re going to be very hungry (and maybe crabby and distracted) if you try to maintain such a low energy intake for a long time.

No matter how much you weigh, exercise improves your overall health. Even if you’re overweight or obese, exercise can help your body better regulate glucose, be more flexible, and have more stamina and strength.

Exercise can affect weight, but enough has to be done. For physical activity to affect your weight, you have to make a commitment to exercise often – possibly every day – at a level of intensity that goes beyond moderate.

Obesity is a chronic condition. Thinking of obesity as something that needs ongoing management, like diabetes, can help people avoid quick-fix diets that may be counterproductive in the long-term.

Overweight children benefit more from programs that involve parents. While weight management programs in schools, daycare, or other places away from the home are convenient, programs that involve a child’s parents and take place at home are likely to be more effective.

More structured meals promote greater weight loss. Programs that offer meal replacements or promote a very structured way of eating are associated with greater weight loss than programs that are based on meals that offer variety and moderation.

Some medicines can help people lose weight and maintain the loss, as long as they continue to be used. While studies have shown this, it’s important to know that some people have been made very sick by weight loss drugs. Always make sure to get your doctor’s approval before you take any medicines to lose weight and schedule regular check-ups so your doctor can assess how all your systems are functioning.

Bariatric surgery can help some people lose weight. For some people who are severely obese, bariatric surgery (surgery to reduce the size of the stomach) can offer long-term weight loss. Still, this is a very aggressive step and isn’t appropriate for everyone.

It’s important to know that many of the researchers involved in this study have financial ties to food, beverage, and weight-loss product companies, including McDonald’s, Jenny Craig, and Coca-Cola. While these ties shouldn’t affect the outcomes of the study, they are important enough that the authors are required to disclose them. One independent researcher not part of the study said the authors’ affiliations raise question about the purpose of the paper and whether it’s aimed at promoting drugs, meal replacement products, and bariatric surgery as weight loss solutions.

No matter your age, one of the best ways to avoid obesity AND help keep your breast cancer risk as low as it can be is to have a healthy diet and lifestyle:

  • eat a diet low in added sugar and processed foods
  • eat a diet rich in unprocessed, nutrient-dense foods
  • exercise regularly at the highest intensity you’re comfortable with
  • avoid alcohol
  • don’t smoke

Visit the Being Overweight page in the Breastcancer.org Breast Cancer Risk Factors section to learn more about steps you can take to maintain a healthy weight.

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