Obesity rates in the U.S. have risen over the last few decades — and so have the myths and misconceptions about the condition. People online as well as mass media often advocate beliefs that lack supporting data, further entrenching misconceptions about f the obesity epidemic in the country.
To compile a list of 16 common obesity myths, 24/7 Tempo reviewed more than a dozen medical sources as well as information from the Centers for Disease Control and Prevention, National Institutes of Health, and other organizations that focus on health.
The causes of obesity are complex and cannot be explained solely by calories in and calories out, or by diet and exercise alone. Many programs treating obesity focus on physical activity and instilling healthy eating habits, therefore ignoring other possible contributors to excess body weight.
Much has been written about obesity and perhaps even more about metabolism, which often undeservedly gets the blame for obesity. It’s hard to separate fact from fiction. These are the 17 biggest myths about boosting metabolism that just won’t go away.
Myth No. 1: Lack of physical activity primarily causes obesity
A common misconception is that obesity is caused by physical inactivity, overeating, or having a poor diet. However, according to current research, these are symptoms of obesity rather than the causes of the condition. How many calories a person burns — whether by exercising or not — depends on several factors, including gut microbes, hormones, and digestive enzymes.
There is also evidence that genetics, stress, medications, thyroid problems, even the foods and other lifestyle choices a baby was exposed to in the womb can contribute to unhealthy weight gain well into adulthood.
While lack of exercise may not be a contributing factor to obesity, lack of sleep is. Sleep deprivation messes with the two hormones that control appetite — ghrelin, which tells you you’re hungry, and leptin, which tells you you’re full. Lack of sleep leads to increased levels of ghrelin (increased appetite) and decreased levels of leptin (diminished feeling of fullness), possibly leading to weight gain.
Myth No. 2: Eating junk foods leads to obesity
Obesity does not happen overnight. The condition develops gradually over time, as a result of several factors. But eating junk foods — which are normally highly processed foods rich in fat, sugar, and salt — is not the only reason for individual excess body weight and is not behind the obesity epidemic in the U.S., according to Cornell University researchers.
In a 2015 study, they found no significant difference in how much of these foods overweight or normal weight people consumed. In fact, people with healthy weight and those classified as obese consumed “nearly identical amounts on average” of junk food, according to the study, which examined 2007-2008 national data about people’s eating habits based on their body mass index.
Myth No. 3: People who are obese are not physically active
A common misconception is that people who are obese are inactive. A 2011 study found relatively small variations in the amount of steps normal weight, overweight, and obese people walked in the study period. The largest difference was just over 1,000 steps for women and 2,000 steps for men.
The study used accelerometers to measure the activity levels of more than 2,800 adults aged 20-79 years for four days. Though it’s true that the participants’ step counts were lower as their weight increased, the differences were far smaller than the common conception. Men with a healthy weight walked on average 10,577 steps, compared to 9,491 steps for those who were overweight walked, and 8,342 for obese men. The difference among women was even smaller. Considering that someone who is overweight or obese expends more energy with each step, the difference in overall energy expenditures may be really small.
Myth No. 4: Restrictive diets are helpful in the long-term
Approximately two-thirds of people who lose weight by means of a restrictive diet regain it within a year, and almost all regain it within five years. This is why restrictive diets are not associated with long-term weight loss.
A 2020 trials review of nearly 22,000 people, published in the BMJ, found that most diets — including the popular paleo, keto, and Mediterranean diets — result in weight loss and lower blood pressure, but these achievements disappeared after a year.
Eating less and cutting out foods high in fat and sugar, which is what essentially all diets focus on, will usually result in shedding off excess weight. But people often go back to old eating habits after they reach their weight loss goal.
Myth No. 5: Weight loss has no bad side effects
Though weight loss for those with unhealthy weight tends to have physically healthy effects, it may come with certain bad side effects, namely psychological stress and increased risk of depressive symptoms. What’s more, both these effects are known to significantly increase the risk of weight gain. Once a person places significance on body image, any changes may be magnified. They may feel more pressure to maintain their weight and even feel afraid of being perceived as a failure if they gain the weight back.
A 2014 study by the University College London found that losing weight doesn’t necessarily improve mental health. Overweight and obese participants who dropped more than 5% of their body weight over four years were 52% more likely to experience depressed mood than those who stayed within 5% of their initial weight.
Myth No. 6: Exercising is better than eating healthy for weight loss
Exercise alone can help with weight loss but only slightly, usually not more than 5 pounds, according to the National Institutes of Health. One possible explanation is that an increase in physical activity often comes with an increased appetite and less concern over what foods are being consumed, making up for the extra calories burned during exercise. Cutting calories through food appears to promote weight loss more effectively than increasing exercise.
Most people probably come across this seemingly arbitrary formula for losing weight: 80% diet and 20% exercise. The key to weight loss is a negative energy balance, and to lose a single pound, a person needs to achieve a 3,500 calorie deficit. Per the 80:20 ratio, a person would need to burn about 700 calories by exercising and cut 2,800 calories through food a week. If you only want to exercise, you’d have to run several miles a day to lose a single pound in a week.
Myth No. 7: Willpower is enough to lose weight
It’s very common to hear that weight loss is a matter of willingness to stick to a diet or an exercise routine. But, in reality, losing weight is far from being just about willpower, and the experience is unique to every person. Many nutritionists argue that using willpower is one of the least effective methods to lose weight because it focuses on the negative and it gets harder with time.
Obesity is much more about biology than willpower. What works for some people will not work for others. Some people only have to go for a walk every night and skip bread with dinner to lose weight, while others may have to cut dairy and gluten products due to a medical issue and exercise for an hour every day, and even then their weight loss journey could be an uphill battle.
Myth No. 8: The amount of weight loss is all that matters
Most people who lose weight look simply at the scale and notice just one number — the total amount of weight lost. Whether the weight loss came from muscle, fat, or water is unclear. Most popular weight loss programs claim to reduce body weight in just a few weeks, but a significant amount of the weight lost through these programs actually comes from lean muscle and water, according to the National Institutes of Health.
Therefore, it may be more effective to adopt a comprehensive approach to losing weight that includes macronutrient intake and strength training to preserve lean body mass while losing body fat.
Myth No.9: Obese people have slower metabolisms
The claim that slim people have faster metabolism is a stubborn myth. Larger bodies actually have higher resting metabolic rates because they need more energy to carry out basic functions.
Body composition is what plays a big role in how fast metabolism is, not weight. Muscle tissue burns more calories than fat. People who weigh more tend to have faster metabolism because part of the extra weight is muscle.
Myth No. 10: Lack of access to fruits and vegetables is behind the obesity epidemic
About 39.6% of Americans are obese, but fewer than 6% of Americans — or about 19 million — live in food deserts. Food deserts are areas where access to affordable, healthy foods like fresh produce is limited or nonexistent because grocery stores are more than 10 miles away in rural areas and more than a mile away in urban areas.
A recent study, published in the PLOS scientific journal, about the role of fresh fruit and vegetables’ affordability, accessibility and availability, on obesity rates found that educational level, rather than access, is more closely associated with variations in body weight and body mass index.
Myth No. 11: Obesity causes diabetes
It is true that excess weight increases the risk of developing diabetes. However, many people who are overweight or obese never develop diabetes. And many people who are thin have high blood sugar levels.
There is even a name for the condition in which people with normal weight don’t produce enough insulin or the body does not respond well to it — lean diabetes. Though it is not very well understood yet, doctors think lean diabetes is a kind of Type 2 diabetes.
Myth No. 12: If close relatives are obese, I will be too
The relationship between obesity and genetics is complex. Understanding the role of genes in obesity is a fairly new field. Recent studies have found that certain genes associated with obesity contribute only slightly to the higher obesity risk. According to the CDC, “no single genetic cause can be identified” in most obese people.
However, according to a 2011 study of more than 218,000 adults, one specific gene linked to obesity — a variant of a gene called FTO — is associated with a 20% to 30% increased chance of obesity. A review and meta-analysis of the FTO gene variant found that people who have it “respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions.”
Myth No. 13: Obesity is only a problem in rich countries
More than 2 billion people around the world were classified as overweight or obese in 2016, and about 75% of them lived in low- or middle-income countries, according to the World Bank.
Myth No. 14: Obesity is a problem only for adults
Early childhood is a period of rapid growth and therefore many people assume that young children who have extra fat would eventually lose it. But children don’t necessarily outgrow obesity or being overweight. They can’t just eat anything and recover. A 2014 study published in the New England Journal of Medicine found that 5-year-olds who carry extra weight were four times as likely to be obese at 14 compared to their peers with normal weight. Of the children who became obese between the ages of 5 and 14, nearly half were overweight in kindergarten.
Overweight and obese adolescents are more likely to have a range of health issues, just like adults. In a study of almost 500 school students aged 15 years, overweight or obese boys were more likely to have a chronic condition such as elevated blood pressure and cholesterol and abnormal levels of insulin (suggesting a form of pre-diabetes) than boys whose weight was in the healthy range.
About 19.3% of children ages 2-19 in the U.S. were classified as obese in 2018, according to the CDC. A decade earlier, 16.9% of children in that age group were considered obese.
Myth No. 15. You gain weight because of slow metabolism
Metabolism is the process by which the body converts food into energy. What influences metabolism is body size and composition. Being fit and having more lean muscle tissue is one way to speed up metabolism. The fitter you are, the more lean muscle you have, resulting in more calories being burned both at rest and while exercising.
Myth No. 16. Sugar-free foods are better for a healthy diet
Sugar-free foods are marketed as a healthier option. But they are often loaded with artificial sweeteners, which are much sweeter than sugar, to make up for the lost taste. Diet soda, for example, is linked to a possible host of issues, including increased calorie intake overall, dementia, kidney problems, and Type 2 diabetes. Some research has shown that artificial sweeteners may induce sugar cravings, alter metabolism, and result in weight gain.
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