What Actually Causes Obesity? Popular misconceptions about weight gain: Stop the Patient Blame Game

Successful prevention or treatment of obesity is fraught with many difficulties, including challenges in having open patient-clinician conversations and overcoming stigma.

These difficulties are further heightened because obesity is often considered to have a simple cause, when in fact it is a complex disease with a multifactorial etiology.

Effective treatment of obesity requires a careful understanding of the facts and myths surrounding this disease and its various causes. Here, I will provide evidence-based explanations for the various causes of obesity as we examine some popular misconceptions.

Misconception 1) 'Food Causes Obesity'

To address this misconception, let's first consider the example of edema. Water balance is usually precisely controlled by the body through multiple hormones and mechanisms. Edema results from an impairment of the controls of water balance, not from drinking excessive amounts of water.

Similarly, the body has mechanisms to regulate energy intake and expenditure. The net result of these mechanisms could be a state of energy balance, negative energy balance, or positive energy balance, leading to maintenance, loss, or gain of weight, respectively.

Blaming food for causing obesity is like blaming water intake for edema or the glucose bolus for diabetes.

As declared by the American Medical Association and other professional organizations, such as the Obesity Society, obesity is a disease. The defect in energy balance regulation leading to excessive energy storage in the form of fat is the disease. Food does not cause that defect. Hence, food does not cause obesity.

But food allows obesity to be expressed, just like water allows the defect in heart or kidney functions to express edema, or as a load of glucose allows the detection of impaired glucose clearance in diagnosing diabetes.

Although obesity has many causes, as we'll discuss below, its current treatment involves creating an energy deficit by reducing food intake. The fact that reducing food intake may produce weight loss is often considered proof that obesity is caused by food. However, that does not demonstrate its role in causing obesity. Often, cause and treatment are not two sides of the same coin. Excessive exposure to UV radiation may contribute to skin cancer, but its treatment does not involve placing a person in a dark room, away from sunlight.

Misconception 2) 'Obesity Is a Choice'

A popular and simplistic assumption is that energy balance is completely under volitional control, which stems from the observation that individuals control their food intake and physical activity. However, the numerous controls up- and downstream that collectively determine energy balance is ignored.

There are numerous physiologic factors beyond volitional control that influence energy balance and keep energy storage within a reasonable range. Such nonvolitional controls may explain why some individuals eat seemingly huge amounts of food but have lean body weight.

Misconception 3) 'Calories In, Calories Out'

A popular misconception is that weight gain can be predicted using simple math of calories: If you gain 1 lb, you have eaten 3500 calories more than your requirement.

The dominance of genetic over environmental influence on body weight was also demonstrated in a study that showed a strong link between the body weights of adopted children and their biological parents, but not at all with their adoptive parents. These studies indicate a stronger influence of genetics on determining body weight than food or related habits of a household.

Furthermore, the body has mechanisms to resist changes in body energy stores, which can offset mathematical expectations based on calorie intake calculations. Leibel and colleagues showed that bodies that were overfed resisted weight gain by increasing metabolic rate.

Alternatively, on a weight loss diet, metabolic rate was decreased and weight loss was resisted. These studies suggest that mechanisms beyond a person's voluntary control regulate energy stores and can make it easier or harder for different individuals to gain weight.

Misconception 4) It's Just a Lack of Willpower

If we were asked to reduce the rate of breathing to 10 times per minute, we would certainly be able to comply. The critical question is, for how long?

Some individuals may harbor a gut microbe composition that is conducive to greater calorie extraction and weight gain, or some may have less brown fat, which may result in reduced utilization of calories.

If energy balance is influenced by impairments in the brain, satiety and hunger hormones, other hormones and enzymes, gut microbes, or the amount of brown adipose tissue, lack of willpower cannot be solely to blame for energy surplus.

If we were asked to reduce the rate of breathing to 10 times per minute instead of the usual 16-18, we would certainly be able to comply. The critical question is, for how long?

Similarly, it is a tall order to expect a person to volitionally eat substantially less than what the person's brain, gut, and physiology are asking for, for months and years on end. This is not an issue of willpower for only a select few; it is unrealistic and unsustainable for most individuals.

Misconception 4) 'Who Cares About Why? Just Eat Less.'

The word "cancer" encompasses many different conditions, with etiologies as varied as smoking, UV light exposure, or viral infection, depending on the cancer type. Similarly, the multiple etiologies of obesity indicate that it is a collection of diseases, better referred to as "obesities."

Cancer treatment depends on the type of cancer. Similarly, "obesities" require that the various causes and contributors are identified for effective treatment.

Current obesity treatments include diet and lifestyle management, some pharmacotherapy, and bariatric surgery on a limited scale. These are blanket treatment approaches regardless of the cause. If the individual causes of obesity were to be correctly identified, treatment could be directed to the specific causes, which may be more effective than current approaches.

the example in obesity treatment would be the discovery and use of leptin for weight loss. Most people with obesity are resistant to leptin action and have excess leptin as a result. Some individuals are born without any leptin. These cases typically present as kids with a very high degree of obesity.

Their obesity is not due to excess TV watching or eating junk food, as popularly believed. This type of obesity develops because leptin is absent to provide the usual feedback to the brain about energy status. Hence, the brain fails to take corrective action in response to accumulating fat.

The treatment of obesity due to leptin deficiency is not diet or lifestyle modification but simply leptin replacement injections.

Another example is the treatment of obesity that results from proopiomelanocortin (POMC) deficiency in the brain. Melanocyte-stimulating hormone is produced from POMC and conveys the anorexic effect of leptin via the melanocortin-4 receptor (MC4). POMC deficiency leads to impaired stimulation of MC4, resulting in greater energy intake. This condition is effectively treated with an MC4 agonist drug.

Deficiency of leptin or POMC is obesities of genetic origin that are successfully treated with a cause-specific approach. Other examples of contributors to obesity that informs treatment include endocrine disorders such as hypothyroidism, Cushing syndrome, or inadequate or poor sleep quality. These few examples underscore the need for further research to uncover additional causes of obesity and how they could be effectively treated.

Successful prevention or treatment of obesity is fraught with many difficulties, including challenges in having open patient-clinician conversations and overcoming stigma.

These difficulties are further heightened because obesity is often considered to have a simple cause, when in fact it is a complex disease with a multifactorial etiology.

Effective treatment of obesity requires a careful understanding of the facts and myths surrounding this disease and its various causes.

Bariatric surgery can be a powerful tool for weight loss in Very severe cases